A. Manufacture of Chocolate.
The Preparation of the Cacao Beans.
Up to the end of the eighteenth century the manufacture of chocolate was carried on entirely by hand, a method at once laborious and inefficient. The workman used to kneel down on the ground, and crush the beans in iron mortars. It was not until 1732[105] that Buisson introduced the use of a bench and so rendered that inconvenient and unwholesome practice unnecessary. Even to-day, the Chinese cooks on the Philippine islands carry their chocolate “Factory” about with them, in which the trestle is essential. It further comprises a small marble mortar and warmed pestle, and by means of these utensils and implements the hulled beans are pounded, and the triturated mass so obtained spread out. It is then flavoured with sugar and spices. With that exception, hand labour in the chocolate manufacture has since the year 1778 been entirely displaced by machinery, when Doret exhibited the first specimen before the medical faculty of Paris. According to Belfort de la Roque,[106] a Genoese named Bozelly had already constructed a mill by means of which he was able to prepare from six to seven hundred pounds of chocolate daily, comparing favourably with the thirty pound output yielded by hand labour. Pelletier[107], in 1819, describes a machine for the mechanical preparation of chocolate of his own construction, capable of doing the work of seven men. The machines used in the chocolate manufacture have since that time been repeatedly improved and re-constructed, although always with this one end in view, namely to obtain a fine even cacao mass, and afterwards mix it as thoroughly as possible with the other ingredients employed.
The first machines of the modern type were constructed by the Parisian mechanic George Hermann (1801-1883) in the year 1830, to which inventor we are indebted for the principle of fine grinding with varying velocities, on which manufacture of chocolate is based to-day. There is at the present time a rather large circle of manufacturers engaged in the putting together of special machines for the preparation of cacao and cacao products, chocolate apart.
Whether chocolate manufacture be carried out on a large or small scale, it always involves the subjecting of the cacao bean to a regularly succeeding series of operations, before the resulting product known as “Chocolate” (in the strict commercial sense of the term) can be obtained.
The respective operations succeed each other as follows:
I. Preparation of the Beans.
1. Storing, cleansing and sorting of raw beans.
2. Roasting the cleansed beans.
3. Crushing, shelling and cleansing the roasted bean (removing the radicles etc.)
4. Mixing different kinds of beans.
II. Production of the Cacao Mass.
5. Grinding the beans till they yield a homogenous paste on heating.
6. Mixture of the liquefied cacao mass with sugar, spices, etc.
7. Trituration by rollers.
III. Preparation of the resulting Chocolate.
8. Extraction of air, division and moulding.
9. Cooling.
10. Packing and storing.
This represents the general course of manufacture, which we will now proceed to describe in more detail, following the headings given above.
1. Preparation of the Beans.
1. Storing, cleansing and sorting.
Right up to the moment when they are to be used in the manufacture, the raw cacao beans must be kept as originally packed, and stored in an airy sun-lit room; although if they have accumulated moisture during transport or sustained any manner of damage in harvesting, they should then be emptied out of the sacks, spread out over the floor of such a room as above described, and dried as effectively as possible. It has also been recommended that such beans be washed with a dilute solution of caustic potash (1 in 5000), and afterwards dried rapidly.
Unfermented beans, those damaged in the harvest, and those which have received no proper fermentation, develop a greyish white colour with occasional tints of violet and an unpleasant, bitter herbal flavour, properties which unfortunately penetrate to the resulting cacao products. Attempts have been made to meet this evil with a so-called “Secondary Fermenting Gordian[108] proposes in this connection that the beans be filled in water-butts, and steeped in warm water for at least 48 hours (so that obviously the butts must be kept in a warm room), at the expiration of which time it can be poured off, and the beans dried in a chamber heated to a temperature of between forty and fifty degrees centigrade. There is said to ensue an appreciable improvement as to flavour and colour, when this process is carried out.
The magazines in which cacao beans are stored have sometimes an unwelcome visitor, to wit, a grub which according to W. Hauswaldt[109] happens to attack just the best kinds of Caracas and Trinidad. As eggs of the grub have on several occasions been found on the interior of the still unshelled bean, we may assume that they were deposited by a butterfly (species unknown, but possibly Ephestia cahiriteller, cf. von Faber loc. cit. page 335) either before or immediately after fermentation, and no later. Sometimes these grubs appear on the surface of the sacks, which they overspread in a few days. Removal of the infected packages, opening the sacks, and exposure to the sun, as well as a thorough cleansing of the storehouses, is attended with a qualified amount of success. The best plan is to destroy the moths during their period of activity in the summer months June, July, and August.
According to Hauswaldt, Stollwerck[110] and G. Reinhardt[111], this can be effected by placing in the store rooms large, shallow basins of water, near which burning petroleum lamps are introduced on the approach of dusk, favourably placed on a pile of bricks and stone, so that they clearly illuminate the reflecting water. The moths assemble round the light en masse and either perish in the water or flame, a fate which sometimes overtakes even the larvae, for they display the same fatal attraction for any light, real or apparent. The water must be changed every day, as otherwise the wing-dust collecting on its surface affords a means of escape to the insects coming later. As the weather becomes cooler, the doors and windows of the store-rooms should be left open, so that when frost sets in, the rest of the maggots may be destroyed.
The cleansing and sorting of the raw cacao bean is the most important factor in the manufacture of chocolate, and yield a manifold return, for inferior and cheaper kinds of bean which have passed through these processes can be advantageously mixed with finer varieties. The chief object of cleansing and sorting is the removal of foreign bodies and such chance admixtures as sand, pebbles, and fragments of sacking, which are liable to damage the stones used in grinding at a later stage of the preparation, or communicate an unnatural and disagreeable smell to the subsequent roast products. These admixtures are so multiform and various that they cannot be removed solely by the aid of machinery, but must be finally picked out by hand. Mechanical appliances are limited to the removal of pebbles, dust, and possible fragments of iron, after which preliminary cleaning the beans are thrown on straps, where they can be picked by hand. The collector of these foreign bodies would find himself with a rather interesting stock at the end of a few years, as Wilhelm Schütte-Felsche points out.
The cleansing of the raw beans was formerly carried out in so-called roller casks, placed horizontally, and revolving round an axle fitted in the floor, whence it passed upward, cutting them slantwise. In this apparatus the beans were rolled and vigorously rubbed together, and afterwards the hand-picking succeeded. More recently, the roller casks have been displaced by rotary cylindrical sieves, driven by motor power.
Such a machine is illustrated in fig. 12. The beans are lifted to a rotatory cylindrical sieve by means of an elevator, where they are freed from dust and dirt; in other sections of the sieve fragments of blossom, sacking, or cloth are isolated, whilst occasional splinters of iron are removed by a large magnet. So prepared, the beans are cast on running belts, and here the hand-picking above-mentioned is carried out.
Fig. 13 shows a cleansing machine for the same purpose, which has recently become rather popular. Here the dust passing from the sieve is sucked up into a dust chamber, by means of an exhauster, whilst pebbles, blossom fragments, and small beans are separately isolated. The cleansed beans pass likewise under magnetic influence, which removes traces of iron, and finally succeed to the running belting.
Often the beans are introduced into an extensive brushing machine before roasting, to cleanse them from dirt etc. These are generally found in such factories as have circular and cylinder roasters with direct heating apparatus. Fig. 13 a shows such a brushing machine for cacao beans.
2. Roasting the Beans.
The cleansed and sorted beans are now subjected to a high temperature, that is to say, they are now roasted. This roasting answers many purposes;
1. The aroma and flavour of the bean is so developed.
2. The starch granules are gelatinised.
3. The herbal constituents are so transformed that the flavour of the beans becomes milder; a distinct improvement.
4. In the consequent drying, the shells are rendered brittle, and more easily removeable.
5. The beans themselves can afterwards be better ground.
The roasting of the cacao bean does not demand so high a temperature as that of coffee, to effect the above chemical and physical changes. Experience has shown that the best temperature lies between 130-140 ° C., though deviations from this standard have recently become frequent and considerable, according to the uses for which the cacaos are intended, and roasting has sometimes taken place at a temperature even as low as 100 ° C.
Fig. 12.
The process of roasting can be carried out in the roasting drum or machine in a variety of ways, as:
1. Direct roasting over a coal fire,
2. Passing of a hot-air stream over the beans,
Fig. 13.
3. Roasting by means of gas, with compressed air, as far as sources of heat are concerned; and as regards shape of the drum, it is to be noted that the cylindrical are most in use. The separation of the shells from the kernel was still effected at the beginning of the present century by stirring the beans in water and so detaching the inner coating of the seeds, the method adopted by Weisched (Mitscherlich page 112). Not till this stage had been reached were they subjected to a strong heat, causing the shells to spring off.
This method has at the present time only historical interest, for the so-called roasting drums, as used in the preparation of coffee, are now universal.
Fig. 13a.
Roasting must be attended with the greatest care, in order that it may neither be too thorough nor insufficient. It is a great mistake to think that the roasting machine can be handed over to the care of any apprentice. That nicety of roasting which corresponds to the variety and its subsequent utilisation constitutes the qualitative basis of the chocolate manufactured later. It is impossible for even the best chocolate maker to retrieve what has been spoilt in this important preliminary operation, wherefore a skilled workman, endowed with a keen sense of taste and smell, is always to be seen at the roasting machine.
It has already been attempted to provide a means of security against over-burning by the construction of the so-called safety-roaster, about which will be spoken later.
Overroasting is immediately indicated by a disagreeable empyreumatic odour (resembling that of roasted coffee); the husks char and the kernels crumble, also betraying a charring on the outside. There is a correspondingly increasing keenness of flavour, and a transference of theobromine from the kernel to the husks (cf. page 65). From the destructive distillation of the cacao fat arises that volatile and pungent acroleine which is the principal cause of the empyreuma of the over-roasted bean.
Fig. 14.
The following general precautions in roasting cacao are worthy of note; 1. the beans should not remain too long in the roasting drum; 2. they should be kept on the stir, for which reason the apparatus is made revolvable on its axles; 3. the heat applied should be carefully regulated; and 4. to guard against a loss of aroma, the roasted beans should be cooled as rapidly as possible.
As the cacao must be more or less roasted according to its quality and ultimate destination, which entails the acquisition of considerable empirical knowledge on the part of the workman entrusted with this process, it would be neither advisable nor practicable to annex definite instructions as to time and temperature requirements.
In the following we describe a machine which is to be found in most factories and which corresponds to all the demands of technique. From its heating system, it belongs to the class of hot-air current roasters—direct coal fire assisting—and in shape to the cylindrical roasters.
Fig. 14 a.
This machine is illustrated in fig. 14 and shown in section in figs. 14 a and 14 b. To prevent loss of heat by radiation, to save fuel, and preclude possibilities of danger from fire, the whole installation is walled in. Driving shafts occur at the back of the machine, and the charging apparatus is introduced in front. A furnace lies directly under the drum, whilst on either side are chambers accessible to currents of fresh air, which are provided with heating tubes and which admit of a regulation of the air supply. They are shut off from connection with the gases from the fire, so that only the fresh air heated here can penetrate to the roasting products in the charged drum. There are winnowing shovels fitted in this, calculated to keep the beans in motion and facilitate the access of air. When the hopper is closed, the gases arising from the roast product can be led off by an annexed outlet pipe, and thereupon condensed and the resulting liquid drained off at the foot of the machine. For the attainment of the proper degree of roasting, as well as for controlling the whole process, there is a sampler to every machine. The drum is emptied whilst in motion, its door-like front being turned aside and the roasted beans transferred by the winnowing shovels before mentioned to trolleys wheeled underneath.
Fig. 14 b.
The loss of heat by radiation is very insignificant, as the machine is completely walled in. Any kind of fuel may be used. Since the stoking as well as the removal of soot takes place at the front, several of these roasters can be set up side by side. It is a great advantage of this installation, that by removal of the front of the drum its interior is laid quite open, admitting of a thorough overhauling which is attended with every disadvantage for the flavour of subsequent roasting lots.
The machine here described is constructed in varying sizes, with an outside capacity of four hundred kilograms.
As already mentioned the so-called safety-roaster offers a certain security against the burning of the beans as the roasting boiler is lifted out of the fire by means of an automatically working safety regulator. Figs. 15 a and b show a spherical roaster open and closed.
Fig. 15 a.
The principal of construction is founded on the fact that each roasting is connected with a loss of weight and it is logical that the same quality of beans always yields the same loss of weight at a certain degree of roasting. On an average cacao yields a loss of 6-7 %. According to this, the loss of weight which can at first be empirically ascertained, for example by a new kind of bean, can be calculated and can be indicated on a regulator, on the principle of the Roman scale. When the beans have lost the weight in question the counterpoise of the regulator raises the axle of the roasting sphere by means of which the working of the whole machine is set in motion.
There is no exception to the rule that only beans of one and the same kind should be roasted and broken up together, as thickness or thinness of the shells determines to a large extent the time required for roasting, and also an even size of bean is necessary to the smooth operation of the breaking machine. The husks of the roasted cacao bean are hygroscopic, and consequently the roasted unshelled beans contain more moisture after having been kept for a time, than they do in the raw state; but the drier the bean is, the easier it shells. The cacao is therefore to be worked up as quickly as possible, or at least kept in well covered metal boxes till further treatment can be proceeded with.
Fig. 15 b.
As sources of heat we find direct and indirect stoking with house coal and coal gas, and besides these, for the installations of larger factories Dowson gas is especially suitable, as it does not involve too high a temperature, and the outlay is not so great as when coal-gas is used.
Fig. 16.
The roasting machine in fig. 16 for Dowson or coal gas belongs to the class of roasters with direct firing. It corresponds to the one diagrammed in Fig. 15 as regards charging and emptying. Here also the front wall of the drum can be removed, and the interior consequently laid completely open. The transmission of gas is effected at an air pressure of one atmosphere, for the attainment of which an air pump is fitted up in the vicinity, capable of feeding four machines at the same time. The drum holds about 150 kilos. It goes without saying that the regulating of the requisite heat is in this instance of the utmost ease and nicety. Another preponderating advantage of this machine as compared with those heated with coke or ordinary coal is its clean operation and the extraordinary speed with which it can be both started and stopped. Form 3-4 cbm. of coal gas are needed for 100 kilos of beans, whilst for Dowson gas, which has not such a high heating value, much larger quantities are required, and consequently a stronger framework becomes necessary, though here no air pumps need be put in operation.
Fig. 17.
Steam roasting apparatus have not proved particularly successful, as has been evident in all experiments hitherto made with them, and steam agency does not appear to be suitable for the cacao bean, it admitting of no thorough and at the same time even roasting.
Yet on the other hand the hot air-current roasters described enjoy an ever increasing popularity, partly because they are heated indirectly, and again because they appreciably diminish the time taken up in the actual process, which in other cases approaches to as much as thirty or forty minutes, without exposing the beans to the danger of burning or getting charred.
As just stated, the beans should be passed on to the next process as speedily as possible, yet on the other hand be completely cooled off, so as to loosen their shells before they arrive in the breaking machine. There are also special constructions for this cooling. If the roasting drums are fitted up directly on the ground, it is effected by disposing the beans issuing from these machines in wide baskets or sieves, and letting them cool there before bringing them to the next process. Should they be situated at a sufficient height, the beans can be slowly transferred down a shoot connected with the rooms below, where crushing mills await them, and cooled on the journey by a play of fresh air currents.
Very much to the purpose and well adapted as regards most of the requisite conditions, are the cooling trucks with exhaust apparatus shown in fig. 17.
These trucks are fitted with perforated false bottoms and with sliding shutters at the side. After the contents of the roasting machine have been discharged into the trucks, these are wheeled over to the exhaust apparatus easily recognisable in the diagram, where the cacao is so far cooled that subsequent “after-roasting” is impossible, whilst the gases given off are conducted by the ventilator. This exhaust chamber can be made to work from both sides.
3. Crushing, hulling and cleansing.
Up to ten years ago, the crushing and shelling of cacao beans had not been so far perfected as to effect the complete separation of husk and radicle from all particles of kernel, or to prevent loss by isolating and collecting the minute particles of kernel, which are drawn up through the exhaust apparatus in conjunction with the lightest of the cacao shells. Yet the requirements demanded of a satisfactory machine advanced to such an extent that not only cacao nibs free from shell were postulated—an end scarcely hard to attain—but shells free from cacao nibs were made a further essential. A machine which performs both these objects not only works excellently, but is also economical. For a solution of this problem the Association of German Chocolate Manufacturers, which is specially interested in all that concerns the chocolate industry, offered a prize years ago; the firm of J. M. Lehmann were the first to construct a machine answering every call made on it to perfection.
Fig. 18 illustrates a crushing and cleansing machine averaging an output of 2500-3000 kilos, of the latest and most modern type.
Fig. 18.
The beans are first broken into smaller pieces in all machines now employed as crushing, shelling or cleansing apparatus, and the one at present under consideration provides no exception. An air-current is made to play on these fragments, which finally isolates and transfers the loosened shells to another part of the apparatus. The cacao next succeeds to a crusher of regular capacity lodged in the upper part of the machine, being despatched on an elevator. The fragments fall into a cylindrical sieve, dust being detached in the first compartment, whilst the meshes of subsequent compartments gradually increase in size and sort the products therein transmitted in corresponding sizes. There is a groove traversed by air-currents—proceeding from a ventilator—immediately under each compartment. This current of air can be regulated, i. e. made weaker for lighter and stronger for heavier fragments, and there is a ventilator for every compartment to make this regulation of the easiest, and in this way shells of equal size but specifically lighter than, the cacao fragments are most efficaciously separated. Contrasting with the older type of machine, it works almost noiselessly, all shakings of grooves and sieves being entirely avoided; in addition to which there is a perfect exclusion of dust, when the shells are transferred into the dust-removing chamber. A further advantage is that there is no wearing out of the machine, except as regards the direct crushing apparatus, which occasionally need renewing.
The dust particles before mentioned, which possibly comprise as much as one half of the cacao fragments, require a special kind of working up, on different machines, before the cacao still contained therein can be obtained. It is a fact obvious and apparent, that the smaller the fragments of shell mixed with this crushed cacao, the more difficult will be their separation, a fact of equal importance to technical and analytical science, and the more scrupulously this process is to be carried out, the greater the lavishment on sieves and ventilating compartments entailed.
To effect this operation on the breaking machine is seriously to overtask the latter, and defeats its own end, as experiments carried out in the Chocolate factory of Schütte-Felsche have proved, inasmuch as it leads very easily to mixing of the products which are to be kept separate.
Fig. 19 shows such a machine for the cleansing of this so-called cacao “dust
The particles are raised to a large flat sieve by means of an elevator, again sorted in different sizes, and submitted to air currents of corresponding strength. The quantity obtained varies according to the variety of cacao, though in some cases it may amount to 50 or 54 percent. What remains after this process is absolutely worthless and can only be considered as refuse, at least as far as the chocolate manufacturer is concerned.
Fig. 19.
It has become necessary in modern manufacture that iron fragments occurring in the machine not only be separated by distinct magnetic fields in the respective machines, but that this also be effected in a machine specially constructed for the purpose. Fig. 20 illustrates such an electromagnetic apparatus. The advantages of this system are that it avoids magnets limited in strength, and by the functioning of strong electro-magnets perfect cleansing even in the case of the largest output, as well as machines of the most simple construction, can be guaranteed.
We submit the following description of the machine and its method of working.
Fig. 20.
The machine contains a hopper with sloping groove to obtain an even introduction of the beans to be cleansed. At the end of this there is an electro-magnet roller, consisting of a non-magnetised mantle and a magnetic compartment round which it turns.
After traversing the sloping groove, the beans succeed to the roller, meeting it at a tangent. As soon as they reach the field of magnetism, all iron fragments are appropriated by the revolving mantle, whilst the beans themselves do not come into contact with this, but pass directly underneath. The iron fragments are disposed of separately, and outside the magnetising area.
It is of prime importance in the preparation of chocolate and more particularly of cocoa powder (easily soluble cacao), that the crushed material proceeding from the crushing machine should undergo a further purification, with a view to separating, and removing the hard radicles. These constitute the gritty sediment of insufficiently prepared cacao powder, when dissolved. J. M. Lehmann effects the complete removal of the radicle by means of his machine D. R. G. M. No. 24,989 (Fig. 21).
Fig. 21.
Here the finer siftings from the crusher are transferred to the controlling feeder, under which a small ventilator occurs, which provides for the removal of any still remaining portions of husk. Cacao and radicle descend to a shaking sieve, the finer particles passing through its meshes, whilst the larger grains fall into a pocket attached to the end, as cleansed product. The former fragments now succeed to a cylinder, having its inner surface punched with small cavities (fig. 22) and while the cacao particles remain in those cavities during the rotation of the cylinder, the radicles of more elongated form are caught up by a special separator (1) and so prevented from being carried round with the rest. The cacao particles are then made to fall into a trough (3) by a brush (2) working against the cylinder, and subsequently urged forward by a conveyor (4). That process is enacted all along the cylinder, so that finally cacao and radicle issue from the machine completely separated.
Fig. 22.
The advantages, economical and otherwise, attending the use of the above breaking and cleansing machines become apparent when the following figures, registering results obtained in several experiments, are considered. Formerly the loss experienced in sorting, roasting, crushing and hulling averaged about 30 % of the total beans, but now the employment of the above machines shows the following satisfactory improvements.
The loss of 823 kg Machala beans, unroasted, amounted to a total:
| a) in picking | 3·6 | kg |
| b) " roasting | 63·5 | " |
| c) " shelling | 61 | " |
| d) " dust | 34 | " |
| 162·1 kg or 20%, | ||
without taking into account the application of the waste; 2267 kg of St. Thomé raw cacao lost:
| a) in picking | 5 | kg |
| b) " roasting | 170 | " |
| c) " shelling | 152 | " |
| d) " dust | 79 | " |
| 406 kg or 20%. | ||
According to these data the use of these machines admits of a saving of about 10 percent more material than in former work.
In connection with these particulars it is also of interest to consider the qualitative and quantitative composition of the various waste products of the manufacture. Filsinger[112] has at the instance of the Association of German Chocolate manufacturers, examined a mixture of 50 pounds of large Machala beans with an equal quantity of small beans, after passing it through a shelling machine of the most modern construction, and he thus obtained:
| 70 | pounds | of | large kernels, |
| 9·2 | " | " | medium kernels, |
| 0·8 | " | " | radicles, |
| 10 | " | " | husk (outer woody shell), |
| 4 | " | " | cacao waste, |
| 6 | " | " | other loss, |
The 4 pounds of cacao waste yielded by further sifting:
| a) kernel | I. | sort | 250 | grammes, |
| II. | " | 50 | " | |
| III. | " | 220 | " | |
| IV. | " | 25 | " | |
| b) husk | I. | " | 185 | " |
| II. | " | 55 | " | |
| III. | " | 370 | " | |
| IV. | " | 80 | " | |
| c) cacao dust | 725 | " | ||
| d) waste | 30 | " | ||
| e) loss | 10 | " | ||
| 2000 grammes. | ||||
Chemical analysis of these portions gave the following results:
| Percentages | ||||
|---|---|---|---|---|
| Ash | Sand | Fat | Fibre[113] | |
| 1. Husk 10% of the raw cacao | 11·15 | 1·90 | 4·50 | 21·36 |
| 2. Cacao waste 4% of the raw cacao | 4·80 | 0·35 | 15·40 | 16·31 |
| 3. Seed shells I. sort ;0·37% of the raw cacao | 6·70 | — | 21·64 | 10·29 |
| 4. Seed shells II. sort 0·11% of the raw cacao | 7·10 | — | 18·39 | 8·75 |
| 5. Seed shells III. sort 0·74% of the raw cacao | 7·20 | — | 15·76 | 12·16 |
| 6. Seed shells IV. sort 0·16% of the raw cacao | 7·80 | — | 16·40 | 12·74 |
| 7. Cacao dust 1·45% of the raw cacao | 11·75 | — | 22·06 | 8·40 |
| 8. Waste 0·06% of the raw cacao | 7·05 | — | 20·44 | 9·81 |
From these data it is evident that there is a great difference between the chemical composition of the so called cacao waste and that of the exterior ligneous shells. From the large amount of fat present in the former material it might be regarded, in the full sense of the term, as a cacao constituent and, for that reason, its presence in cacao preparations should not be objected to, while the husk containing as much as 20 percent of woody fibre cannot be considered a cacao constituent in the same sense.
4. Mixing different kinds.
Stress has already been laid on the variations in taste incidental to different species of bean. It has further to be noted that they develop a milder and more aromatic flavour according as they have been more properly fermented, and in contrary instances possess an astringent and even acid taste. It therefore becomes an aim of the manufacturer so to improve the flavour of inferior varieties by mixing with the finer as to produce a resultant cacao giving perfect satisfaction to every taste. Nevertheless the general rule still holds good that for the preparation of the finest qualities of chocolate only the better sorts of bean (as Caracas, Ariba, Puerto Cabello etc.) should be employed. For inferior and less expensive ware other varieties of bean suffice, the mixture being obviously regulated by the prevailing market prices.
In many instances the proportions of such mixtures are kept secret by the manufacturer as matters of importance, and every individual manufacturer has his own method and specialities as regards such blends.
We compare here a few verified blends:
| 1. | 2. | ||
| Caracas | }of each 1 part | Caracas | = 1 part |
| Guayaquil | Bahia | = 5 parts | |
| 3. | 4. | ||
| Maracaibo | }each 1 part | Trinidad | }equal parts |
| Maragnon | Maragnon | ||
| 5. | 6. | ||
| Caracas | = 1 part | 1 part Ariba | |
| Maragnon | = 2 parts | 1 part Surinam | |
| 1 part Trinidad | |||
| 7. | 8. | ||
| 1 part Ariba | 3 parts Ariba | ||
| 1 part Trinidad | 1 part Trinidad | ||
| 1 part Surinam | 1 part Surinam | ||
| 1 part Caracas | 1 part Caracas | ||
| 9. | |||
| 1 part Machala | |||
| 1 part St. Thomas | |||
Ceylon cacaos are not used so much as mixing varieties, but almost exclusively as covering agents, to make other cacaos lighter coloured (sometimes almost approaching yellow).
The beans are weighed off in these proportions on a sensitive scale, and then passed on to be ground and triturated into cacao paste.
II. Production of the Cacao Mass.
5. Fine grinding and trituration.
Formerly the roasted, crushed, and decorticated beans were frequently ground before being transferred to the “Melangeur”,—a machine that will be described later—, in which they were then reduced to a finer state of sub-division and lastly mixed with sugar. For this grinding, mills of various construction were employed (as Weldon, Pintus etc.). But as time rolled on the Melangeur took the place of these preliminary grinding mills, and in this it was endeavoured to effect that fine division of the cacao mass which is essential to the production of a homogeneous cacao and sugar intermixture, but without complete success. Cylinder rolling machines (French method) were the first to attain this result.
At the present time, the roasted and cleansed kernels are ground so fine as to become a semi-liquid when subjected to heat, and that is done whatever the ultimate destiny of the cacao, whether it be intended for chocolate or cocoa powder. This object is obtained by means of special mills, constructed with “Over-runners
Fig. 23.
Fig. 24 a.
These cacao mills, which were formerly but seldom met with in chocolate factories, have now become indispensable necessaries, since they have the advantage:
1. of rendering the cacao mass in this semi-glucose form more easily miscible with sugar, a factor of the highest importance for the commoner and cheaper qualities of chocolate;
2. of grinding the cacao as fine as possible in one operation and the simplest manner.
Fig. 24 b.
Fig. 24 b.
Fig. 24 c.
But side by side with the appreciation which these mills met with, there arose a corresponding increase in the demands made on them, such as the utmost nicety, greatest possible output, and least possible necessity of after-heating, and these have been successively answered by twin, triple and at the present time even quadruple mills. fig. 23 shows a simple grinding mill which can only come into consideration in connection with the smallest of branches, whilst Fig. 24 a and b illustrates another with three successive stones arranged one above the other, such as will be found in all the larger factories of to-day. Also a triple mill but with grindstones of increasing size pictured in fig. 24 c. A mill possessing four pairs of grinding stones is given in fig. 25, and is calculated to meet each and every conceivable demand.
Whilst simple, double and triple mills are brought on the market in different sizes, corresponding to the outputs required, these quadruple mills are only constructed in the largest sizes. They grind perfectly, and without detriment to the flavour, deliver quantities of cacao figuring at from 1000 to 1200 kilos daily. There is naturally a larger output if the fatty contents of the cacao are considerable, a thorough roasting being always presupposed.
The axles occurring on these quadruple grinding mills are connected with one another by means of spur-wheels, and the axles themselves run in ball-bearings, which not only permits a perfectly noiseless operation of the machine, but also makes the action very easy, that is to say, dependent on only very little motor power. The cacao is raised to the hopper by means of an elevator, where the quantity introduced into the machine is regulated, and then passes between crushers occurring in the middle of the first pair of grinding stones, which it subsequently leaves as a pasty mass. It is then conducted along a groove into the second mill, and here undergoes further grinding, and so to the third and fourth, where the process can be described as trituration, for the cacao leaves the machine in liquid form. Only in this manner is it possible to obtain the finest ground product, without any disastrous accompaniment of excessive heating.
Cacao mills with one stone suffice for the production of chocolate mass on a small scale, but for the manufacture of cocoa powder, twin or triple grinders must be employed.
All these are of the “Over-runner” type, act by their own weight, and consequently do not involve the disastrous consequences which were entailed by the “Under-runners” tried formerly.
About the middle of the nineties of the last century, experiments were made with a view to superseding these types with mills having stones of varying sizes, and first larger upper stones of a grinding pair were tried, then larger under stones, but neither have been able to maintain themselves in the workshop, and the grinders of equal size still hold good as the fittest and most popular.
Fig. 25.
Attempts have recently been made to introduce a machine combining mill and roller. Its value lies in the fact that with a relative increase in the grinding rapidity, it does not involve a greater than requisite heat, and on emerging from the machine the cacao shows no deficiencies as to flavour, and is withal much finer than that produced in other processes.
Fig. 26.
Fig. 26 shows such a machine. The mill on this serves merely to reduce the hard kernel to a pulp, and this admits of the grinding stones being placed farther apart, and so occasions no heat. Trituration is then effected by a roller apparatus, for which operation machines with four rollers have been proved most satisfactory. As such roller machines are furnished with water-cooling systems, it is possible for the cacao to be kept cool even on these.
6. Mixture with sugar and spices.
Fig. 27.
A thorough mixing with sugar can only be effected when the cacao paste is heated to a temperature rather above the melting point of cacao butter, that is to say, as high as from 35° to 40° C., and consequently the incorporating machine in which that operation is carried on is provided with a steam jacket. For this process it is advisable to have the chocolate in a semi-liquid condition, wherefore the ground cacao issuing from the mills is transferred to steam-heated vessels (fig. 27) fitted with taps suitable for drawing off the mass as it is required. Formerly the cacao mass was fed into the melangeur in lumps and there liquefied. But as this necessitated the application of heat to the melangeur, attended with the risk of cracking its under-plating, and also a postponement of the mixing processes, whereby considerable time was lost, this method no longer obtains to-day. It is at present usual not only to warm the cacao mass beforehand, but the sugar also, by storing it in warm chambers, so that the whole paste possesses a uniform temperature, lowering of temperature in the melangeur is avoided, and there is consequently no waste of the heating steam.
In some large factories the actual incorporation of cacao and sugar is preceded by a preliminary mixing of large quantities, which considerably relieves the strain on the melangeur, whilst it keeps the machine rooms as far as possible free from superfluous dust.
Fig. 28.
The mixing machine shown in fig. 28 can here be used with advantage. As will be seen on comparing the illustration, it is provided with a shifting trough. Such a machine, when closed down, is capable of mixing from 100-500 kilos of chocolate. The mixing is effected by means of two suitably shaped blades, and the heating by a steam jacket. After the operation is completed, the mixed material is turned out into portable troughs, and after having been kept in a warm chamber for some length of time, transferred to the melangeur for further treatment.
It has been found advantageous to keep the chocolate mass so obtained in suitable receptacles for several days[114], at a temperature of not less than 20° C. and between that figure and 40° C. So the sugar is enabled to penetrate the entire mass, which now proceeds to the rolling processes carried out in the melangeur and rolling machines. Shortly before its discharge from the latter, it is mixed with spices, vanillin, eatherial oils and so forth.
Fig. 29.
7. Treatment of the Mixture.
a) Trituration.
In describing the mixing machines, we do not intend to enter into details regarding the machines formerly in use, but merely to give a brief outline of the principles illustrated in their construction.
Trituration was formerly produced;
1. by rollers running backwards and forwards on a grinder;
2. by several cones rotating in a circle on a disc-shaped bed;
3. by means of rotating stones running in a trough;
4. by means of several cylindrical rollers;
5. by means of grooved cone moving in a grooved casing.[115]
At the present time only the type mentioned under 1. and 4. are in general use. 3. is met with less frequently, and will be described at greater length in a subsequent paragraph.
The machines 1. and 3. are put into operation prior to the cylinder rolling mills, which finish off the incorporation of chocolate and sugar and the levigation process only begun in the first-named.
The machines constructed in the manner described under 3., to which we now turn, were introduced by G. Hermann of Paris, but are at present almost obsolete. Since they have some historical interest and are typical of the development of the melangeur, we annex a rough sketch showing their general construction in fig. 29.
The ellipsoid runners a made of granite work in the trough i which is also of granite and is fitted with the casing h. The runners rotate on their axles b so as to move in a circle. The two arms of the axis b have at the centre an elliptical ring with a quadrangular opening, into which fits the similar shaped part of the vertical shaft c fitted with the toothed wheels, d and d′, which are set in motion by power transmitted to the shaft and its connections. The arm b has some play downwards, so that it can adjust itself vertically according to the greater or less quantity of material in the mill. The two steel blades, e and e′, are shaped to fit the cavity of the trough; being connected with the shaft c they revolve with it and sweep down the cacao mass adhering to the sides of the mill. Between the foundation k and the trough i there is a space l into which steam can be introduced through f, the condensed water passing away by g.
All machines of this kind have now been displaced by the melangeur which is capable of turning out a much larger quantity of material with a relatively smaller expenditure of power. The operation of mixing chocolate is not a mere mixing, for the pressure exerted by the runners is also an indispensable factor. On that account the ordinary mixing machines have not proved serviceable, especially in the case of chocolates containing a small amount of fat, such as the cheaper kinds, while the addition of cacao butter to facilitate the working of the machine would considerably increase the cost of production. Melangeurs are generally constructed on the same principle as the edge runner grinding mills which are so much used; but they differ from them in so far as the bed-stone revolves, while the runners merely rotate on their axles without revolving.
Fig. 30.
The melangeur with travelling bed-stone, as constructed by Lehmann, is shown at fig. 30; it is fitted with an arrangement for lifting out the runners.
Fig. 31.
The bed-stone as well as the runners are made of granite. Each runner has an axis working in plummer blocks, so that it can be lifted out independently of the other one. By that construction the runners are prevented from taking an oblique position as was the case with the mills formerly made, since one runner would be forced downwards or tilted on its outer edge whenever the other one was raised up somewhat. The bed-stone of this machine revolves and it is easily heated by steam pipes from below. One important advantage of this machine is that being low it can be very easily charged and emptied. The contrivance for lifting out the runners prevents them thumping upon the bed-stone that might otherwise readily happen when starting the machine, and it also lessens the wear of the driving bands; moreover, large lumps of sugar or cacao are very readily crushed down and, so, the working is much facilitated. The emptying of the melangeur is readily and safely effected, while the bed stone is revolving, by holding a shovel so that the cacao is thrown up against the shovel. A melangeur of this construction is represented by fig. 31; it has three runners and underneath the bed-stone is fitted a steam engine which supplies driving power, the exhaust steam being used for heating the machine.
Although this emptying by hand is not attended with any serious drawbacks, yet it involves loss of time and is rather inconvenient, so that the demand for mechanical automatism in this operation was very considerable. It is now some years since Messrs. J. M. Lehmann patented an apparatus for the mechanical discharging of the chocolate mass from these machines, but their invention still holds good. A melangeur provided with such apparatus is shown on fig. 31. Here a vertically moving shovel is sunk behind the outlet, gradually damming the material, and causing it to rise above the edge of the tank and fall through the opening. A second but horizontally working arrangement, which in this case as in the last is controllable by means of a crank, conducts the remainder of the material to the same shovel. So the material is discharged within a few minutes.—These melangeurs are built for varying outputs. Fig. 32 illustrates one of the largest yet constructed. Its base has a diameter of 2 metres, and the machine itself has a capacity of 5 cwts. To avoid the mixing of dust with the sugar as far as possible, the whole melangeur is provided with a dust-proof protector.
b) Levigation.
An extreme fineness and homogeneity of the chocolate mass is obtained in the employment of cylindrical rolling machines, for the construction of which we are indebted to G. Hermann of Paris. Every kind of chocolate must be passed through the rolling machine at least once or twice even when finely powdered sugar is used, though in this case it is less a question of sub-division than of incorporation and intermixture. The best qualities are passed through the machine from six to eight times, or even more. The mass is finally fed into the machine in cold blocks and so ground off. Granite is the material chiefly employed in making the rollers, although it is not every variety which can be adapted to this purpose. Apart from the fact that granite, or indeed any other mineral stone, seldom occurs in compact masses and free from flaws, neither porphyry nor the stone generally described as granite is suitable for employment in the construction of mill rollers. A kind is generally preferred which intermediates between granite and porphyry as to hardness and possesses excellent grinding capacities, and which goes by the name of diorite. No other stone can compare with this diorite in respect to the above qualities, and the chief firms engaged in the construction of roller machines possess their own quarries. But we shall return to this later, for recently experiments with case-hardened casting rollers (Krupp steel) and hard porcelain have yielded very flattering results.
Fig. 32.
Fig. 33 a.
Fig. 33 b.
We shall now enter into more detail respecting the principle illustrated by these rolling machines. The plasticity of the chocolate mass necessitates a rotation of the cylinder surfaces in opposite directions with dissimilar velocities. Accordingly two or more rollers are caused to work against each other, and in compliance with this principle of sub-division with differential velocities, their axles are fitted with wheels, of which each has a different number of cogs.
So those rollers furnished with the greater number of teeth revolve more slowly, whilst in opposite instances there is a corresponding acceleration.
Fig. 34.
The construction of the machines now in use differs more or less from that of the type first invented by Hermann, plan and elevation of which appear in figs. 33 a and 33 b respectively.[116]
The granite rollers at a1, a2, a3 are fitted with an octagonal iron axle that is somewhat thicker at the interior part and they are mounted upon a frame as shown in the drawing. The sockets of the central rollers a2 are fixed and each one is held in position by three sets screws; those of the two other rollers can be shifted along grooves in the frame and when the cylinders a1 and a3 have been brought into proper position relatively to the cylinder a2 they are held fast by the set screws p.
Fig. 35.
Fig. 36.
For the purpose of this adjustment, there is at each end of the machine a horizontal wrought iron shaft f that can be turned by the winch e, and these shafts are fitted with two endless screws d working in the corresponding wheels c. These occur on the spindles a, which screw in and out of the bearing blocks of the rollers a1 and a2, but turn only in the fixed collars b without being shifted from their place. The result is that on turning the cranks e the corresponding cylinder a1 or a3 is moved nearer to, or further from, the central cylinder a2, while the position of all of them always remains parallel. The shaft Q is set in motion by the driving wheel L fitted with the loose wheel L1. It acts first upon the cog wheel K which works in the larger wheel J on the axle of the central roller a2. That works in the cog wheel O and the wheel P fitted to the roller a1 driving them as well as the wheel M and the pinion N of the roller a3 The result is that the axle a2 makes 1¾ revolutions and a3 6-1/8 revolutions while a1 in the same time makes only one revolution.
Fig. 37.
The cacao or chocolate is supplied to this machine by the hopper R which is placed between the rollers a1 and a2. The pasty mass adhering to the rollers is carried forward by the quicker moving roller a2 and it is ground finer between the rollers a2 and a3, after which the material is removed from a3 at the outer side by an adjustable blade gg and then falls down into a receptacle below.
Figs. 38 and 39.
On the design fig. [34]34 we see a machine of more modern construction ready mounted. The receptacle parts of the same are arranged and connected in full agreement with the above mentioned except that the motion is effected by the driving power fitted to the machine on the ground on the left side.
Fig. 40.
The principle of this roller machine has long been applied in the building of other types, and we find that these, variously altered, renovated and improved, are to-day an indispensable equipment in every chocolate factory. In the following pages we give a description of some of the best-known constructions of refiner.
The so called battery rolling mills constitute a remarkable innovation. It is apparent that the more rollers a cylinder machine contains, and the greater their length and diameter, all the more efficacious will the working of the machine be. Batteries have accordingly been constructed, whereby two, three or more roller systems are combined, one to every three rollers, and rising one above the other, so that they slant upwards much as shown in Fig. 40.
As the battery rolling mills possessed the disadvantages that they took up too much room and could not be well fed and regulated, they are generally replaced by rolling machines of from 6 to 9 rollers, first constructed by J. M. Lehmann. These rolling machines of 6 to 9 rollers which we see before us in Figs. [35]35 and [36]36 are really systems of 3 rollers fitted one over the other. They therefore take up the room of a 3-roller machine and are quite as easy to work.
Fig. 41 a.
As will be seen from the design of a nine-roller apparatus, fig. 37, the chocolate mass descends from one roller system to the other, and is fine rolled in a third of the time otherwise required, and at one operation, with corresponding saving of labour. The nine roller apparatus are provided with landing stage and steps, and fed either by means of elevators, or from above.
Fig. 38 shows a recent construction, three roller apparatus (case castings, cf. below) standing vertically, which accordingly takes up little room. The hopper is low-lying, whilst the discharging is effected from the upper roller, and accordingly admits of the occasional use of a somewhat larger size of transport trolley. This type also occurs with 6-9-12 rollers, as apparent from fig. 39.
Fig. 41 b.
Whilst these systems were exclusively supplied with rollers made of granite or hard porcelain up to a few years ago, it has been found that good results are obtained by the use of cast rollers, and they have been for some time employed on machines of three, four and five rollers. (Figs. 38, 40, 41 a-c.) In consequence of the non-porous surface of these steel rollers, it is possible to grind to a finest powder, merely in one operation, without passing the chocolate through the machine several times; and the so-called “Burning” of masses which have not been properly mixed cannot arise in this case, though it is true that the apparatus must be provided with water cooling arrangements to avoid a too excessive heat. They are specially adapted to the preparation of the more ordinary qualities, and are even occasionally employed for finer chocolates, for obviously these must be again submitted to a rolling process, when granite or porcelain rollers are preferred.
Fig. 41 c.
For this reason the 6, 9 or even 12 roller mills have been more discarded since the last grinding process has been performed by granite rollers (cold process).
In order to avoid the disadvantages of the pulley drive, it is in certain cases advisable to drive each machine direct from an electric motor. Fig. 42 illustrates a refining machine driven in this manner.
Fig. 42.
c) Proportions for mixing cacao mass, sugar and spices.
The relative proportions of cacao, sugar, and spices, as well as of starch as in the manufacture of the cheaper sorts, vary considerably. Generally speaking 50 or 60 parts of sugar are added for 50 or 40 parts of cacao mass; the following are a few formulae applicable for the production of those kinds of pure chocolate that are most used.
| A. Hygienic chocolate. | ||||
|---|---|---|---|---|
| Cacao mass | } equal parts of each. | |||
| Powdered sugar | ||||
| B. Spiced chocolate. | ||||
| a) | b) | |||
| Cacao mass | 4 kg | Cacao mass | 4 kg | |
| Sugar | 6 kg | Sugar | 6 kg | |
| Cinnamon | 72 g | Cinnamon | 130 g | |
| Cloves | 38 g | Coriander | 8 g | |
| Cardamoms | 16 g | Cloves | 88 g | |
| Oil of lemons | 2 g | |||
| Cardamoms | 16 g | |||
| c) | d) | |||
| Cacao mass | 5 kg | Cacao mass | 5 kg | |
| Sugar | 5 kg | Sugar | 5 kg | |
| Cloves | 80 g | Cinnamon | 100 g | |
| Cinnamon | 220 g | Vanilla | 100 g | |
| Mace | 8 g | or Vanillin | 2·5 g | |
| Mace | 2 g | |||
| Cardamoms | 4·2 g | |||
| e) Spanish spiced chocolate. | ||||
| Cacao mass | 5 kg | Cardamoms | 82 g | |
| Sugar | 5 kg | Mace | 44 g | |
| Cinnamon | 116 g | Vanilla | 40 g | |
| Cloves | 50 g | or Vanillin | 1 g | |
| Oil of lemons | 1 g | |||
| C. Vanilla chocolates. | ||||
| a) | ||||
| Cacao mass | 5 kg | |||
| Sugar | 5 kg | |||
| Cinnamon | 160 g | |||
| Vanilla | 50 g | |||
| (or Vanillin | 1·2 g) | |||
| b) | c) | |||
| Cacao mass | 4½ kg | Cacao mass | 4 kg | |
| Sugar | 5½ kg | Sugar | 6 kg | |
| Cinnamon | 150 g | Cinnamon | 120 g | |
| Vanillin | 1·5 g | Cloves | 20 g | |
| Vanillin | 1·6 g | |||
The powdered spices as given above may be replaced by corresponding essential oils, but see page [237] for remarks on this point.
If the chocolates made from beans rich in oil contain too much fat to mould properly, a small percentage of their constituent cacao mass can be replaced by cocoa powder made from the same kind of bean, but defatted, in the case of the finer qualities; and when inferior varieties are under consideration, the same result may be attained by a sufficient increase in the proportion of their other constituent, sugar, as e. g. 55-60 parts of to 45 or 40 parts of cacao mass, so disturbing the usual equality of the two ingredients mixed together. Very cheap chocolates in particular are prepared from a smaller percentage of cacao mass and show a corresponding increase in their sugar content. But if the sugar exceeds 65 percent, it is no longer possible to mould these chocolates, and the addition of fresh cacao butter becomes a necessary preliminary to this operation, cf. also the first part in section IV. Such varieties would have a composition somewhat like the following:
| Cacao mass | 25 | parts |
| Sugar | 67 | " |
| Cacao butter | 7 | " |
| Spices and vanillin as above | 1 | " |
In the experimental preparation of samples of chocolate mass it is not advisable to employ large quantities of ingredients, when a waste of material is bound to ensue, but to begin with mixing small quantities of one or two kilos. The small Universal Kneading and Mixing Machines, Patent Werner & Pfleiderer, Type 1, Class BS, can here be used with advantage. They are specially intended for small outputs and experimental work; but we shall return to their description later, after stating that they are furnished with heating apparatus, stuffing boxes and air-tight lid, and can easily be taken to pieces, greatly facilitating the removing of the mass.
III. Further Treatment of the Raw Chocolate.
8. Manufacture of “Chocolats Fondants
Fig. 43.
Recently the creams sometimes described as in the heading have enjoyed a vast popularity, and are sold as eatable chocolates in ever-increasing quantities. As far as can be ascertained, they were first manufactured in Switzerland, melt readily, and have a correspondingly large amount of fat, resulting from the addition of cacao butter, which distinguishes them from ordinary chocolates. When readily melting chocolates were first introduced, it was a prevailing opinion that the required property could only be obtained by increasing the amount of fatty content. Now the excessive evidence of fat in chocolates is very objectionable, both as regards taste and digestibility. To avoid this, therefore, the chocolates are treated mechanically, to attain the required character of readily melting. The machines used for that purpose are termed “Conches”, because the trough, in which the chocolate is rubbed into a long cylinder, has somewhat the shape of a long shell. For the working up of chocolates in conches, the necessary conditions are;
1. that the chocolate should have been ground perfectly fine,
2. it must contain such an amount of fat as to become glucose on warming, not indeed so thin as that used as coating material, but nevertheless softer than the ordinary cake-chocolate of good quality.
Fig. 43 a.
Fig. 44.
The machine can be heated by means of steam, hot water pipes, gas or charcoal stoking, according as they are available in the place of installation, and the temperature should rise above 70-80° C. for fondants, and 50° C. for milk chocolates. In factories with water power or electricity, continuous fondant machines can be worked day and night, but when only worked during the day, must be kept warm overnight. Constant tending of the machine is unnecessary, as it works automatically. After a treatment of from 40-48 hours, the chocolate attains the requisite character (i.e. it melts readily), and a rounding off of taste, which are the properties of all good brands. Milk chocolates can also be advantageously prepared in the conche, as also covering or coating cacaos of all kinds, which harden considerably in consequence of this treatment.
Figs. 43 and 43 a show quadruple conches of the modern type with hot water, wherein four troughs are arranged in pairs, and one opposite the other. Conches with only 1 and 2 troughs are also constructed, and in various sizes, the troughs sometimes having a capacity of 125 and 200 kilos, so that the quadruple conche is capable of holding five or eight hundred kilograms in all. The curved bottom of the troughs, as well as the rollers fitted in them, are made of granite, and the front wall strongly bent in at the corner, so that the mass is forced over the border of the front wall, where there are openings for its discharge as well. To prevent radiation as far as possible, it is best that the troughs be walled in, the troughs are either walled. Fig. 44 shows the room of a modern chocolate factory, with 15 conches.
“Chocolats fondants” are from a gastronomic point of view, the finest chocolate product on the market, and it is not remarkable that this branch of the chocolate manufacture has witnessed a considerable extension, and is likely to extend still more.
9. Heating chambers and closets.
The manufacture of chocolate has been very considerably facilitated by the introduction of heating chambers and closets, which have now become an indispensable feature of every factory in the industry. In these chambers the chocolate which has still to be rolled, as well as that already submitted to this operation, is stored and kept at a temperature of 60° C. until it can be further treated (moulded). This manner of heating involves an appreciable cheapening of the production, for masses which are dry and apparently require an addition of fat recover in such a manner during a twenty four hours’ storing in the heating chambers that such addition becomes unnecessary. But especially when chill casting rollers are employed, which the mass leaves in a very dry state, the use of these heating chambers is indispensable. They should be available in every factory to such an extent as to find room for the total output of one day, though even twice or three times this amount might very well be provided for. Closets heated by steam are best adapted for small factories, such as are illustrated in Fig. 45. They possess double doors, are walled in, and are capable of holding from 300-400 kilos of chocolate mass for each metre of length. Larger factories should furnish themselves with chambers, which are more open to access and on the walls of which iron shelves can be introduced, heated by steam pipes arranged underneath. A typical chamber, measuring 2·8 metres in breadth (including passage) and 5 metres in length would hold about 2,500 kg of chocolate.
Fig. 45.
10. Removal of Air and Division.
Fig. 46.
After emerging from the final rolling process, the chocolate is stored up in heating chambers until it is ready to succeed to the moulding, prior to which, however, it must be freed from air and cut up into small portions. Until recently, it usually came next in a melangeur provided with a dish-shaped bed-stone made of granite, as illustrated in fig. 46, where it was kneaded and reduced to a uniform plasticity and heated to the temperature required for moulding. The melangeurs devoted to this purpose are now superseded by special tempering machines.
A machine of this recent construction, used for working solid and semi-liquid material, is shown in fig. 47. The tank intended as a receptacle for the chocolate mass is in this case made of iron and, to facilitate cleaning, smooth in the interior. It runs in a water-bath, the supply in which can be controlled by steam or cold water. The granite runner is provided with a lifting device, admitting of the working up of material containing foreign ingredients like nuts, whole and fine-split.
Fig. 47.
The mass is taken out of the machine in lumps, and in order that it may be reduced to a temperature suitable for the removal of air (about 26-32 ° C. on the outside) it is laid to cool on wooden, marble or iron tables. When this temperature is arrived at, large lumps of chocolate are introduced either into the air-extracting or the dividing machines.
Fig. 48.
After the importance of the tempering processes had at length been recognised, inasmuch as the maintenance of the temperature prescribed is of immense influence on the chocolate subsequently produced, and it had on the other hand been ascertained that such machines as described above could not be absolutely relied upon, for the shaking tables involve an occasional excess of tempering, the idea of a machine which should completely and automatically perform this task was finally conceived. This new machine, given in fig. 48, and already differing from all other tempering machines in external appearance, ushers in an entirely fresh process respecting the modus operandi prevailing in the present manufacture of chocolate, which does not fail to satisfy the highest expectations. It may be said to work continuously, for no matter what the temperature of chocolate passing into it may be, the material leaves the machine at the temperature desired within a lapse of one minute. According as more or less chocolate has to be turned over in the moulding department, the machine can be stopped or set in motion without detriment to its efficacy. Besides this, it cleans almost automatically, so that a quick change of quality is always possible. The special virtue of this machine is that it turns out the material with such a degree of homogeneity as has never before been known, making moulding at much higher temperatures a possibility. There is yet another side issue, namely a doubling of the life of the moulds, and finally, owing to the fact that the often considerable amount of waste material is done away with in this process, the moulding shop is spared to some extent. The series of rollers through which the chocolate passes is maintained at a proper temperature by means of automatic water apparatus. The daily output of the machine figures at 3000-4000 kilograms. The material is passed on out of this machine to the dividing and moulding processes.
The necessary extraction of air follows immediately on the tempering process, for the blades of the scraper then release the chocolate mass from the rollers in thin layers, between which air penetrates. The removal of air is effected by machines, an old type of which is shown in fig. 49 (in front elevation).
It can be warmed by means of a charcoal fire placed in the space i, or by any other suitable means. The chocolate mass is fed into the cylindrical hopper a, at the base of which occurs an archimedian screw b, which is propelled by the shaft and cog-wheel system c d e in the direction indicated by the arrow. Thus the chocolate mass is forced into the box f, leaving which in cylindrical form, it succeeds to the travelling band h. It is now almost entirely freed from air. As the material is pushed forward on the band, it is cut off either by a knife g fixed to the box f, or divided as far as possible into equal parts by a double knife with adjustable blades corresponding to the weight required for a chocolate square. This manipulation presupposes a fair amount of skill on the part of the machinist, but this once attained, the division ensues as precisely and simply as can be desired.
Air-extracting machines of recent construction, although still partially built on the above principle, are at the same time generally developed as automatic dividing machines.
Fig. 49.
Fig. 50.
Fig. 50 shows such a machine for solid and semi-liquid chocolates. By means of this, the material is next conducted along a vertical screw path in even mass to the horizontal screw, and so a second filling with the hand is rendered unnecessary. After it has been freed from air in this, it enters a revolverlike cutter, which discharges the divided portions on a travelling belt. On the latter it is conducted to a table standing near, where it is laid into moulds. The machine is of very strong make, and puts out from 15-250 gr, divided into approximately 10-25000 squares, within a space of ten hours.
Fig. 51 a.
Figs. 51 a and b give finally two of the best known types which have a very extensive application, protected by patent imperial (Germany), and built by J. M. Lehmann, Herm. Baumeister, J. S. Petzholdt in Döhlen, G, near Dresden and others. With this patent dividing machine of J. M. Lehmann, solid and semi-liquid chocolate material, as also nut and almond chocolates are divided exactly, in any weight from 18 to 250 grammes, and then conducted in strips of equal size to the mould previously mentioned. As far as cleanliness, purity, and easy management are concerned, it fulfills all the demands which can be expected of the most modern machine.
Fig. 51 b.
IV. Moulding of the Chocolate.
11. Transference to the Moulds.
Fig. 52.
The pieces of chocolate, on emerging from the dividing processes, are placed separately in iron moulds, that is to say, as far as this has not already been done in the dividing machine. It is important that these should have the same temperature as the chocolate mass, in order to prevent the formation of spots on the surface of the cakes, and to obtain a good and non-greyish fracture. The temperature for moulding smaller objects can be fixed at between 27° and 32° C. and for the larger may be considerably lower. In summer also, moulding may be proceeded with at a lower temperature than in winter. According to a note in the Gordian (1895, No. 4) the moulding may be carried out in summer, when the atmospheric temperature is;
- from 25-31° C, at 26-27·5° C
- " 18·5-25° C, at 28·5-30° C
- " 12·5-18·5° C, at 31-32·5° C
In cold weather, the cakes may be moulded at a temperature of from 32·5-35° C., according to their thickness. When not manufactured in the automatic machine shown in fig. 48, the mass should be otherwise controlled as regards temperature, which should be registered by a thermometer introduced therein. The moulds are for the most part filled with plastic and liquid chocolates, and their depths determined and modified by the weight of material which they are destined to receive.
Fig. 52 shows a machine which conducts the semi-fluid mass to the moulds in the following manner. The moulds are automatically introduced under the apparatus, and filled from the small stirrer above. They then succeed to the shaking table and are finally transported to the cooling room. On this machine moulds of from 75-350 mm long and 75-225 mm broad can safely be employed.
There are two different forms in which chocolate is sold, namely, that intended for domestic purposes, and that which is to be consumed as an article of luxury. The kinds known as cake, rock and roll chocolate belong to the first class, the several pieces weighing 50, 100, 200, 250, 500 up to 5000 grammes. Tin-plate is the only material of which moulds are made; and these generally have a capacity rather greater than is necessary for holding the particular quantities to be moulded. The chocolate is therefore, as described above, divided into given weights, and generally deposited direct in the moulds by the dividing machine. The divided portions of chocolate are pressed down in the moulds by hand, equally distributed in the latter, and then transferred in the moulds to the shaking table or combination of shaking tables to be described later. On the shaking table the soft chocolate soon penetrates completely into all the corners and impressions of the stamped tin moulds. The removal of the cooled cakes from the moulds is easily effected by pressing.
These moulds are generally provided with from four to ten ridges or indentations, so that the chocolate can be conveniently divided, and as required for use. Others again have a similar number of compartments.
The compartments may be impressed with any kind of inscription, so that such information as the name of a firm can always be reproduced on the cakes.
Broken chocolate is generally of inferior quality, brought on the market without any protective covering.
In those kinds of chocolate which are known as articles of luxury a distinction is to be made between;
1. Those moulds which are in one piece and completely filled with chocolate, so that the superfluous mass can be removed by a knife. In such cases the weight of the cakes is exactly regulated by the capacity of the moulds.
2. Those intended for moulding various figures of fruit etc. in which two or three parts make a closed space which is of the form desired.
Among the moulds of the first type must be numbered those used in the preparation of small tablets and sticks, and the sweetmeats known as Napolitains and Croquettes.
The second class comprises moulds for making chocolate cigars and chocolate eggs, and also the double moulds.
The moulds for the smaller tablets, cream sticks, napolitains and croquettes are also made exclusively from tin-plate, and the separate parts are enclosed in a stout iron frame, the top of which is ground down smooth, so that any superfluous portion of the filling can easily be scraped away. In that way from six to thirty pieces can be cast in one mould at the same time: the cooled chocolate can be released from the moulds by gently tapping one corner against a table. In napolitain moulds protecting hooks are attached, to avoid their sustaining any injury in this operation.
Examples of the more frequent moulds.
1. Chocolate Cigars.
These are made either by introducing the chocolate mass between the two halves of a double mould, of which each corresponds to a half of the cigar shape to be moulded and which each fit exactly one on the other; or else by pouring it into hollow moulds stamped out of one complete piece. Moulding presses[117] are utilised in the manufacture of material en masse. In these the cigars are filled into iron moulds, afterwards held together by means of iron combs, and so introduced in to the press. For each size and shape special moulds and plates are essential. Neither barium sulphate nor zinc white may be employed to produce an imitation of the ash on ordinary cigars, as both are objected to by health inspectors; nor are they necessary, for in phosphate of lime (tricalcium carbonate) we possess a perfectly harmless and at the same time efficient substitute, when it is mixed up with starch syrup.
Other figures, such as fish etc., may also be produced in chocolate, by means of the moulding press, when it is furnished with stamped moulds, corresponding to the forms required.
2. Chocolate eggs.
These are generally made hollow, unless they are very small, by pressing chocolate in two halves of an egg-shaped mould and then uniting the two parts. Another method patented by Th. Berger of Hamburg[118] seems less practical. A mould is made of soft sheet caoutchouc blown out; this is dipped into liquid chocolate and, after the adhering coating has hardened, the air is let out of the mould. The use of caoutchouc moulds would render this method too costly, since the alternation of temperature soon makes the caoutchouc unserviceable.
3. Various figures, fruits, animals, and other small objects.
Double moulds are used for making these objects in chocolate, consisting sometimes of three or four parts; they are made either of sheet iron, tinned, or, for more complicated forms, the moulds are cast in tin, but these latter are not so durable as those of tinned sheet iron with strong iron frames.
The several parts of the moulds, after having soft chocolate mass pressed into them, are put together and excess of material is removed by requisite pressure by the use of a press of the kind made by A. Reiche in Dresden, which will admit of a large number of moulds being placed in it at a time. By the use of such a press the moulds are protected from injury, and the objects moulded have a better appearance, as a result of the uniform as well as strong pressure exerted.
After cooling, the moulded objects are readily detached from the moulds and they only require to be scraped clean, or further ornamented as may be desired. That is done in various ways, for example by painting with coloured cacao butter.
4. Crumb Chocolate.
This term is applied to the small pieces of chocolate of truncated conical shape, with from 4 to 5 smooth surfaces. They are made by a machine specially constructed for the purpose by A. Reiche (No. 1550); it consists of a four-cornered box with a removable bottom. Inside the box there is a false bottom, from 1 to 2 cm above the other bottom, which is fitted with a removable sheet iron plate, in which pentagonal holes are stamped. A knife can be introduced at one corner of the bottom of the box. After sufficient chocolate has been made to penetrate through the pentagonal holes by agitating the box on the table, the knife is rapidly drawn across the bottom and the box raised up. The sheet iron plate is then taken out, and by gently tapping one corner the small pieces of chocolate are shaken out.
5. Small tablets, sticks, fruits or figures filled with cream.
These are prepared by pouring the cream contents in either wooden or iron moulds, previously dusted with a little flour, and then moulding round them chocolate in whatever form is required, always taking care that this is kept as soft and plastic as possible, a suitable addition of cacao butter proving invaluable for the purpose.
In former times chocolate moulds were manufactured exclusively in France, where the firm Létang of Paris enjoyed what was to all intents and purposes a world monopoly. But since the year 1870 the oft-mentioned firm of Reiche in Dresden-Plauen has taken up the manufacture, and has succeeded in conquering the market in a remarkably short time. The moulds of this firm satisfy each and every possible requirement, although it would be no disadvantage if the old type of pattern mould were cleared away at one and the same time with the old routine, to make room for a little artistic skill and embellishment.
Recently Reiche has brought out a special machine intended as an easy and practical cleanser of his many moulds, which include bonbon cutters and cutting rollers, numbering stamps, chocolate slicers, roller machine boxes etc. He has lately brought on to the market a special machine for quickly and efficiently cleaning the moulds, which is illustrated in fig. 53.
In one end, a circular brush is introduced, and against this the moulds to be cleaned are firmly pressed. In consequence of the large number of revolutions which this brush passes through, the moulds are cleansed of still adhering masses of chocolate in a half or third of the time occupied when hand labour is employed. At the other end of the shaft occurs a duster, sprinkled with Vienna white (a lime), which polishes off the moulds previously and thoroughly cleaned by the circular brush. The great advantage of this machine is that the daily expenditure on polishing is considerably reduced One girl can do the work of two hand workers, when this machine is employed. In addition, it makes possible a continual touching up of the material used in the making of the moulds, a ventilating apparatus removing all traces of dust.
Fig. 53.
12. The Shaking Table.
The pasty chocolate mass fills itself into the chocolate moulds spontaneously, in consequence of its soft consistency. Yet to share it evenly throughout the mould, so that it adapts itself to every bend and hollow there occurring, and further to bring to the surface any possible bubbles of air evident in the mass, the chocolate is whilst still in the moulds subjected to brisk shaking.
This is effected by placing the chocolate on trays and transferring these to the shaking table, of which types and construction are at the present time manifold and various, the best and oldest being given in front elevation below (Fig. 54).
Fig. 54.
The movable slab a, fitted with an upright rim at its edges, has underneath two projecting pieces d, working against deeply toothed wheels e, which fastened on the shaft b, are driven round by the pulleys c. The teeth of the wheels catch on the projecting pieces at every revolution of the shaft and push them rather gently on one side, and when the tooth-points slide from under the slab, it drops down as much as it has been previously raised. Each tooth of the wheel coming into contact with the projections, the same motion is repeated several times, causing the slab to oscillate up and down.
This oscillation of the slab is controlled by means of a hand lever f, occurring on the shaft g, and fixed crosswise thereon, so that we can only show it in cross section on the diagram. The lever f attaches itself to the under part of the slab, raises it, and so throws the wheels out of contact with the projecting pieces, but without stopping the rotation of the shaft b.
Shaking tables have also witnessed considerable improvements with the lapse of time, and we shall now proceed to treat these in more detail, especially as several recent constructions offer and illustrate many interesting mechanical points.
Fig. 55.
Fig. 56.
An old type of machine, that is nevertheless still much employed, is illustrated in fig. 55. Here the slab is caused to osculate by shaking wheels introduced underneath, each possessing six, eight, or more teeth. The slab is raised and lowered by contact with wedge-shaped parts, the effect produced being greater or less according as the moulds are large or small, heavy or light, and in proportion to the consistency of the chocolate mass which they contain, e. g. whether it is solid or semi-liquid.
Quite an improved construction is shown in fig. 56. Here the table is attached to a vertical axle, which is moved up and down by means of a toothed wheel fixed on its bottom end. There is also a cylinder arrangement under the whole machine to assist in controlling the vertical motion of the shaft, and as it is provided with automatic lubrication, there is no danger of any wearing out of the apparatus and consequent irregularity of functioning.
The shaking and jerking of the slabs is in itself attended by a considerable amount of noise, and when to this is added that caused by the tables, it will be seen that a chocolate factory may become to its neighbours a very serious source of objection. For years attempts have therefore been made to construct shaking tables, so that they would not cause any greater noise than is absolutely inevitable. Pneumatic contrivances and caoutchouc have met with right royal success in this connection.
Fig. 57.
The most recent and probably the most perfectly constructed shaking table is given in figs. 57 and 57 a. It embodies all the latest improvements and is self lubricating, a fact of the highest importance as releasing the strain on the attendance, which would need to be very perfect to ensure absence of noise in the case of a machine making 800 strokes a minute. When it is considered that the moulding room is generally managed by girls who neither possess knowledge of, nor interest in, the machines, the advantages of such automatic lubrication become even more apparent.
Fig. 57 a.
Figs. 58 and 58 a.
Apart from the automatic lubrication, in itself a sufficient guarantee for the efficiency of the machine, screws and nuts are entirely avoided on this machine. The motive mechanism is also interesting. By a special arrangement, the number of revolutions in relation to the number of the elevations of the slab is reduced to one fourth, viz., from 760 to 190. Since the elevation of the slab can be regulated to zero, a loose pulley for shifting the driving belt is unnecessary; in addition, the driving shaft makes only a small number of revolutions, and works in oil. The round shaped upright serves to carry the vertically moving frame i, which supports the slab moving in an oiled groove at s, and which is supported underneath by the pivot m. Both at m and s there is automatic lubrication. The bearings of the spindle n, attached to the upright, work into left and right screw threads at oo, to which points the ends of a broad leather belt p are attached, passing over the roller g, by which the frame i is suspended. The driving pulley k, running in oil, carries in its centre the four rollers l, which turn round and round the pulley k, so as to come into contact with the belt p and press it outwards on both sides. At the same time it shortens the belt in the vertical axle, so raising up the table slab i. This is repeated four times by one revolution of the driving pulley, so that working with 190 revolutions a minute, the slab is raised 760 times. According as the screws oo are moved to or from the centre, the vertical movement of the slab can be increased or decreased to a point when the slab is completely out of action, i. e. when the rollers l no longer touch the belt p. Under favourable local conditions, a number of such tables can be driven by one shaft, so that only one pulley and a single driving belt would be needed, though each table would work quite independently of the others. Such an arrangement is shown in figures 58 and 58 a.
Fig. 58 b.
This shaking table, though only recently introduced, has quickly made itself popular, and is especially suitable for the preparation of readily liquefiable chocolate. The gentle vibratory motion produced by this shaking table and its exact adjustability admit of the thinnest cakes being made in a perfectly uniform thickness, without any objectionable projections round their edges. Besides the shaking tables of this construction there are others made in such a way that whether the moulds are light or heavy, small or large, the slab is always raised to the same height, the working of the slab being adjusted by altering the number of revolutions. The manipulation of these tables is much more difficult than that of tables constructed as above described, and that is probably the reason why these have for decades been scarce on the market.
The moulded chocolate spread out on trays is transferred as rapidly as possible to the cooling chamber, with which we shall conclude section IV.
Instead of several shaking tables alternately receiving the moulds, which involve frequent changes, so-called shaking systems (fig. 58b) have been generally adopted of late. They consist of a number of shaking tables, having their frames attached to each other, possessing a common motor control, and having their slabs arranged one after the other in such a way that the filled moulds slowly proceeding from the dividing machine can be automatically conducted over them. The shaken moulds are then passed on to further processes, or they enter the cooling chambers at once. The advantage of the shaking table system lies in a reduction of the number of hands, who only need to be in attendance at each end of the system, and further in the regularity, both as regards time and strength, which prevails in connection with the shaking of each mould.
13. Cooling the chocolate.
Experience has shown that the more rapidly the moulded chocolate is cooled the finer is its texture and the more uniform the appearance of the fractured surface. That is due to the formation of smaller crystals of the fat when the cooling is rapid, while in slow cooling larger crystals are formed and the fracture consequently becomes dull and greyish.
Formerly it was possible to distinguish chocolate made in summer from that made in winter by the more uniform appearance of the fracture, that was, in the latter case, the result of more rapid cooling.
At present, however, manufacturers are no longer dependent upon favorable atmospheric conditions in that respect, for by suitable arrangements it is now possible to produce the reduced temperature requisite by artificial means.
The most suitable cooling chamber is an underground space which should, however, be so situated as to be in convenient communication with the moulding room. The cheapest and simplest place for a cooling chamber is a cellar, if it be properly constructed and dry, as well as large enough to contain the quantity of chocolate made in one day’s working. The best temperature to be kept up ranges from 8° to 10° C. Within those limits there is no danger of the chocolate being coated with moisture, or that it will acquire a coarse grained texture by lying too long. The following rules will serve for guidance in regard to this point:
Generally, chocolate presents the finest fracture when it has been fully levigated and when it contains a considerable amount of fat, provided that the fat present is only cacao butter. Those kinds which are not so well levigated, or have had some addition of foreign fat of higher melting point, show an inferior fracture. It is possible to obtain an equally vitreous fracture in a less cold cellar (16° C. and upwards) when the chocolate is moulded at a temperature corresponding to that of the cellar; to effect that, the chocolate should be moulded at a proportionally lower temperature the warmer the cellar is. The difference can be seen by the appearance of pale red spots on the surface. When it is desired to dispense with artificial cooling, the cellar should be as much as possible below the surface of the ground; it should also be of sufficient height, not less than 3 m. If the situation and height of the cellar be properly adjusted, the requisite area for disposing of a daily production amounting to 5000 kilos would be 400 sq. m. The cellar must be well ventilated and furnished with double windows, so placed as to open towards the north and east. Discharges of warm waste water, as well as steam pipes or furnaces should be kept as far distant from the cellar as possible. The internal arrangement of the cellar should be of such a nature that the whole of the chocolate to be cooled can be deposited upon the floor, since that is the place where cooling takes place most rapidly. With that object in view it is desirable to construct brickwork pillars about 25 cm high, covered with white tiles. Passages are arranged between these pillars. The cellar should be entered by as few persons as possible and, therefore, the cooled cakes of chocolate should be taken at once, in the moulds, to an adjoining room to be turned out and passed on to the packing room and store.
Most of the existing factories, that have been established for any time (large and small) have had to adopt artificial means of cooling, because in most instances the quantity of chocolate to be cooled daily has, in course of time, increased tenfold. The machine rooms have been enlarged, the number of machines has also been increased, while the cooling cellar has remained in its formerly modest proportions. But those circumstances are not the only reasons for having recourse to artificial refrigeration, which is often necessary in consequence of the inconvenient situation of the cellar and the high underground water level.
In the application of artificial refrigeration in a chocolate factory it is not advisable to hasten the cooling of large quantities by producing too low a temperature in small chambers. The cakes of chocolate mass by that means come out of the moulds as hard as glass, but it is questionable whether the consumer using the chocolate many months afterwards, will make the same observation. Great care would have to be taken with such rapidly cooled chocolate, to pass it gradually through chambers of a medium temperature and thus prepare it for exposure in the packing rooms and warehouses. Even when employing artificial means for cooling, the reduction of the cellar temperature and cooling upon pillars is to be preferred to the more direct cooling upon a system of pipes, which after all is nothing else than a cooling upon ice, as may be in some instances the only alternative. Consequently, a well constructed cellar for cooling, furnished with a system of cooling pipes on the roof is perhaps the most advantageous arrangement, especially for large factories.
In carrying out artificial refrigeration various kinds of machines are used for reducing temperature, in which the desired effect is produced either directly by the condensation and evaporation of suitable materials, such as liquid carbonic acid, ammonia, sulphurous acid, or indirectly by making saline solutions (calcium chloride), cooled below the freezing point, circulate through a system of pipes fitted on the roof or walls of the space to be cooled. As the cold liquid is pumped through the pipes, it takes up heat from the air in contact with them, correspondingly reducing the temperature of the cooling chamber. The cooling installations of the firm of C. G. Haubold, junior, Chemnitz, are among the best and have long been extensively used in the chocolate industry. Their cooling apparatus is a compressing machine, in which coolness is obtained by the evaporation and recondensation of such liquid gases as carbonic acid or ammonia. Like all compressing machines, it is comprised of three main parts.
I. The evaporator or refrigerator, consisting of a wrought iron system of pipes. The latter are placed in the spaces of the plant to be cooled, with a so-called direct evaporation arrangement, and are either arranged on the walls and ceiling, or built in a special chamber as dry or moist air coolers, according to the quality of the chocolate to be cooled, or the use for which it is destined. Whilst in the former case cooling is effected directly in the rooms, in the latter the air of the cooling room is conducted to the air coolers by means of ventilator, in order to be cooled and dried there, and then again introduced in the chamber.
II. The compressor, a gas suction and pressure pump, working both simply and complex, which draws the refrigerating medium out of the evaporator, compresses it, and forces it along to the condenser.
III. This condenser consists of a coil of wrought iron or copper pipes, which are enclosed in a barrel and are often described as the immersion condenser. There is another type, in which the pipes are united to one or more pipe-walls, introduced in a vessel which collects and drains off the condensations. In both cases the coil of pipes is played upon by a continual stream of water, in order that the gases which they contain may be condensed. The immersion condenser is generally employed when there is a plentiful supply of cheap water at hand, and the other in contrary cases. This latter condenser is provided with a separate liquid “after-cooler”, constructed on analogy with the before mentioned immersion condenser. The counter current principle holds good in both types, and admits of a better using up of the cooling water. The liquid gas then passes on to the evaporator, where it is responsible for further refrigeration.
Fig. 59a.
The refrigerator also occurs in the form of a brine cooler. In this construction the evaporating pipes are likewise enclosed in a barrel, containing a high percentage of salt brine. In consequence of the refrigerating apparatus occurring on the interior of the pipes, the brine contained therein is cooled down to a very low temperature, pumped along to the cooling chambers, and after delivering its alloted refrigeration unit re-conducted to the cooling apparatus, where it is once more subjected to the same series of processes.
A well-known arrangement for such artificial refrigeration is that constructed by Wegelin & Hübner at Halle o. S., in which carbonic acid is employed, and it has been found well adapted for use in chocolate factories. The accompanying illustrations figures 59 a and 59 b represent an arrangement of that kind in which the cooling is effected on cooling trays judiciously arranged.
The refrigerating machine is constructed on the carbonic acid gas compression system; it consists of 1. the compressing pump a, 2. the condenser b, and 3. the system of pipes c and d, that constitute the refrigerator. The coil of pipes in the refrigerator is connected at one extremity with the compressing pump and at the other extremity with the condenser. Liquid carbonic acid passes from the condenser into the coil of pipes and is there evaporated. The heat necessary for that change is withdrawn, either directly or indirectly, from the cooling chamber and from the chocolate placed in it, until the desired reduction of temperature is brought about.
Fig. 60.
The compressing pump a is a peculiarly constructed suction and pressure pump, it draws out of the refrigerating pipes the vaporised carbonic acid by which they have been cooled and then subjects it to a pressure which helps to effect its reconversion into the liquid state.
The condenser b consists of a coil of pipes over which a current of cold water is kept flowing and the compressed carbonic acid vapour, passing from the compressor into these pipes, is there cooled and condensed by the surrounding water, so as to be transferred back to the refrigerator through a valve fitted to it for that purpose. The outer vessel of the condenser is constructed of cast-iron, in one piece with the compressor frame. These cooling arrangements are constructed either with or without mechanical ventilators. In figures 63 a and 63 b the compressing pump and condenser are represented as placed on the ground floor, while the refrigerator is situated in the cellar space lying beside them and at a lower level, in such a manner that both the systems of cooling pipes are not situated upon the roof of the cellar, but run along it at regular distances parallel to the side walls of the cellar. The compressor and condenser form one apparatus and the former is driven by a steam engine.
In the cooling cellar, the refrigerator is generally fixed to the walls in such a way that the warm chocolate, taken into the cellar, can be at once placed upon the stages formed by the system of cooling pipes, and so there is some advantage in having the system of cooling pipes fitted along the roof of the cellar.
The machine which is diagrammed in fig. 60 possesses an hourly output of some 70000 calories, measured in salt water at -5 ° C. The compressor is driven directly by an electric motor, and a stirring apparatus is put in motion by the crankshaft of the compressor, the two being connected by an intermediate gearing.
Wegelin and Hübner put out cooling plants with salt water cooling, smaller and medium sized plants are on the contrary provided with so-called direct evaporation.
The diagram in fig. 61 shows an air-cooler as built of late by Esher, Wyss & Co. for chocolate cooling plants.
These air coolers are especially used for direct evaporation of carbonic acid gas. They consist of three groups of ribbed wrought-iron pipes, the whole constituting a system supported in a frame work of U-shaped and angular iron. The separate tubes are welded and bent together. The ribbed bodies are in themselves square shaped, and apart from the tube opening have a nozzle introduced in their centre, which pressed firmly against the press pipe effects a favourable transmission of heat in the case of large surface areas of the support, the more so as the tubes are square shaped.
Among the numerous advantages of this machine can be numbered the abolition of the refrigerator and brine pump, prompt and instantaneous refrigeration when the machine is started, and ease of control, as a flange connection occurs immediately in front of the machine.
Fig. 61.
A wrought iron trough is fitted up underneath the air-cooler to catch the water drops. Above, and to the left, the three systems of the air-cooler are connected by means of a catch.
In the foreground of the illustration is given a miniature of the ribbed tube system, which very clearly illustrates the arrangement of the separate ribs.
A ventilator not apparent on the diagram conducts air to the tubes in the cooling chamber, and these present a considerable cooling area, in addition to which, the air-stream taking a parallel direction, resistance to its passage is reduced to a minimum.
Another method of cooling[119], that is carried out in France consists in placing the moulds, containing cakes of chocolate, upon a travelling belt running horizontally through the whole length of the cooling chamber. The requisite reduction of temperature is effected by apparatus similar to that described above in Wegelin & Hübner’s arrangement. The liquefied carbonic acid flows through a system of pipes fitted to the roof of the cooling chamber, producing by its vaporisation the necessary cooling and then it passes back to the refrigerating machine. Circulation of the air in the cooling chamber is provided for by a suitable ventilator under the pipes of the cooling system, gutters being fixed to carry away any water condensing upon their surface and prevent it from falling upon the chocolate. The travelling belt passes along so slowly that the moulds, containing chocolate, placed upon it at one end, take from ten to fifteen minutes in passing to the other end where they are taken off and carried to the packing rooms.
Fig. 62.
Another cooling arrangement that works very well is constructed by T. & W. Cole of the Park Road Iron Works, London E.; figure 62, represents a plan of this arrangement, which has the great advantage of providing for the exclusion of moisture from the cooling chamber. Refrigeration is effected, by means of Cole’s Arctic-Patent Dry Cold Air machines, by compressing atmospheric air and then allowing it to expand, after being cooled by water and having moisture removed by suitable arrangements. The machine is of very solid construction; it works at a pressure of from 70 to 80 atmospheres and drives the dry cooled air through a system fitted in the cooling chamber where the chocolate is spread out, either on portable trucks or on a travelling belt, so that it remains in the chamber long enough to become perfectly cold. The system of cooling can be changed in various ways. The sudden removal of the cold chocolate into another chamber where the air is moist, would be attended with a deposition of water upon the goods. For that reason the goods are first transferred, for a short time, to a warm chamber (ante-room) where they acquire a temperature at which no deposition of moisture can take place. The chief advantage of this arrangement is that it furnishes dry cold air economically, both in summer and also in a moist climate. Cole guarantees that this machine will effect a refrigeration of 5 ° C.; according to the statement of Messrs. Negretti and Zambra the cooled air contains only 40 % of moisture. The cold air from one of these machines can be led, by a well insulated run of pipes, to any part of the factory and thus be made available for cooling purposes in different places.
The cooling plants hitherto described may be classified as “Space Coolers”, because in each case a special compartment of the cooling chamber must be utilised. The increased prices of estate constitute no mean objection to such a system.
A critical valuation of these plants brings out a few undisguisable deficiencies. A large proportion of the cold is lost in the chamber itself, before it has been of any avail; and then again the rooms are generally insufficiently, sometimes even not at all, insulated from adjacent and warmer chambers, which once more involves raising of the low temperature essential in the process.[120] Detrimental also is the presence of the personnel, the illuminations, and many minor influences. It is evident that the larger the output required the larger must the cooling chamber be, involving corresponding economical waste.
With the recognition of these evils arose the problem of their abolition. The aim was to employ small chambers and avoid loss of cold air. It is now solved by a system already used in many and various industries, namely, cooling in closets. Larger or smaller closets may be employed, as required, and in consequence of their thorough insulation may even be introduced into the warmest rooms. Their principle is maximum efficiency with minimum occupation of space, and avoidance of loss of cold as far as possible. In consequence of this latter aim, the refrigerators in this case can be constructed on a smaller scale than those destined for an equal output of material, which are fixed up in cooling chambers; or they may be larger, which is yet more important, for the efficiency of the machine under consideration can be considerably increased by connecting it with one of the closets.
There are two sorts of cooling chambers, those which transport the moulds automatically, and those which contain layers where the moulds are placed one over another. Both types are cooled by the circulation of air, so effected, that cooled air currents are sucked up by a fan out of a tubular system fitted underneath a horizontal partition, and then forced along to the chambers above, where they are evenly distributed over the rows of sheet-iron, laden with moulds, or where they play upon the travelling belt which transports the moulds out of the cooling chambers. The air passes once more into the tube chamber on the opposite side, where it delivers up the warmth it has in the meantime acquired, to enter finally the same system of circulation as before. The general temperature of the closets is a mean between 8 ° C. and 10 ° C., and the cooling lasts from 20-40 minutes, according to the strength and size of the tablets. As the temperature never goes lower than 8 ° C., it is impossible for the tablets to become moist when exposed to the warmer outer atmosphere. Fig. 63a shows a Cooling Chamber built by J. M. Lehmann, which is adapted for a daily output of some 1000 kilos, and divided into compartments one above the other. The sections of this chamber, which in the illustration plainly shows the small amount of space required for its erection, are divided by vertical cross-partitions into four compartments, each of which is provided with a shelf or stand to take a charge of 10 cooling trays, and accessible by three spring-doors, thus giving as small apertures as possible and reducing the loss of cold when charging to a minimum. In addition to this, each compartment is fitted with a contrivance for regulating and, if necessary, completely cutting of the draught. The position of the system of pipes is shown by the two pipe-ends to which it is connected. On the opposite side, or front of the chamber, is the fan-drive, either a small electric motor, or shafting. The perforated cooling trays are visible through the open doors. The sides of the chamber consist of two layers of wood with thick slabs of cork between them. All chambers of this system, including those with automatic conveyance of the moulds, can be taken to pieces for transport, the single pieces afterwards only requiring to be fastened together again when erecting the chamber.—The chamber illustrated serves for cooling moulded chocolate. For pralinés and the like similar chambers are supplied, which are, however, smaller and lighter in construction.
Fig. 63b represents a cooling chamber with forced air circulation and automatic conveyance of the moulds, built by the same firm. This chamber, which, owing to the travelling belt conveying the moulds, is of considerable length, is nowhere connected with the outside air; the whole manipulation of the moulds is carried on through small adjustable openings at the points where the travelling band enters and leaves the chamber. The band consists of chains in links on to which wooden laths are screwed and its speed can be regulated to suit the size of the tables to be dealt with. The width of the belt and chamber can at any time be varied to suit the place of erection and correspond with the length.
Fig. 63 a.
Fig. 63 b.
Fig. 63 c.
As is to be seen from the illustration, this cooling chamber requires the minimum of attendance and thus complies with the principles lately adopted in all large factories, in which the tendency is to substitute as much as possible mechanical appliances for manual work. It will be seen from the preceding chapters that this tendency is especially marked in the moulding department, where automatic tempering, moulding and mould-filling plants and shaking tables have already been introduced. In order to utilise fully such automatic plants the last link in the chain only was wanting, namely, a suitable means of transferring the moulds from the shaking tables to the cooling chamber and through the latter to the demoulding and packing room. The purpose of the cooling chamber above described is to fill up this gap, and its proper place is thus ranged in among the automatic machinery described.
Thus it is that many modern factories have united the above machines to form a single working plant, as shown by Groundplan Fig. 63c.
V. Special Preparations.
a) Chocolate Lozenges and Pastilles.
These chiefly consist of cacao mass, sugar and spices. Formerly they were made by placing the semi-liquid chocolate material on a stone slab, furnished with a rim of uniform height which served to regulate the thickness of the goods manufactured, and then rolling out the mass as required. The lozenges were punched from the rolled-out layer by means of a cutter. After allowing the mass to cool, these lozenges were detached from the remaining portions, which were then rolled again and the same process repeated.
Pastilles, on the surface of which impressions of varying import, such as figures, names, firms etc. are required, may also be manufactured by placing the soft chocolate mass upon tin-plates in which depressions occur corresponding to the device desired. A roller is employed to make the material fit into the depressions, and superfluous chocolate is removed with a knife.
These impressions come out especially fine, when the pastille moulds are subjected to a shaking on the tables with which we are already acquainted.
Fig. 64.
Fig. 65.
Yet these processes are becoming obsolete, and the chocolate slabs or plates are at the present time superseded by the two forms of apparatus constructed by A. Reiche, which we accordingly describe below.
Fig. 66.
In the first of these simply constructed machines, fig. 64, the material oozes through perforations in a square sieve-like arrangement, at length issuing on the sheet-iron plate fitted underneath. The process is aided by repeated shaking, and when sufficient chocolate has penetrated to the plate, the box is raised on its hinge and chocolate mass left ready for further treatment. By gentle additional shaking, the still irregular heaps are rounded off to perfection; they are now cooled down and finally detached. The coating of the lozenges with coloured sugar grains is effected by passing them, together with the plate to which they still adhere, through a box containing sugar dust.
This machine is scarcely used now; in its place come the two constructions of A. Reiche, as already stated, the one being intended for solid material, and the other for semi-liquid chocolate mass.
Fig. 67.
By means of his pastille machine Nr. 14091, which we give in Figs. 65 and 66, chocolate lozenges of the most diverse size can be prepared very rapidly and to advantage. The chocolate material, which in this case is solid, is pressed through perforations in a metal plate and otherwise treated as in previous cases.
In working with this machine, it must be previously and sufficiently warmed, then partially filled with chocolate material of a proper consistency (not more than 75 % of the total capacity may be utilised). It is highly important in the preparation of lozenges that the material should neither be too hard nor too plastic, but strike a just medium.
Fig. 68.
Before pressing down the plunger, worked by a screw, a metal plate is laid upon the chocolate to prevent contact with the plunger. By slight pressure, the chocolate mass is forced through the perforations, according to the required size of the lozenges, but the plunger must not be screwed down further. This will admit of the plate on which the lozenges rest being drawn out and another inserted.
Fig. 69.
To this machine belong the usual perforated plates f, Fig. 66 of which there are three of different sizes for each machine, as shown by figures a b c, also the plates d used for making the perforated confections which find their way to the Christmas Tree. These plates are impressed with larger or smaller designs, and so make two different sizes of goods possible. A third plate is supplied for the manufacture of whole pieces (various varieties of chocolate croquette).
The machine works smoothly and noiselessly and delivers excellent products. If instead of the usual plain lozenges, such with the name of a firm or other device are desired, the corresponding impressions must be stamped out on the plate in which the chocolate is received after being forced through the perforations. See fig. 66, g, h, i.
Fig. 67 illustrates the pastille machine Nr. 14 178 for thin chocolate mass, constructed by A. Reiche (German Patent 227 200). It resembles the foregoing apparatus in principle and appearance, being only distinguished by a different aim, namely the treatment of thin material. Used in conjunction with the peculiar moulds also manufactured by the same firm (marked “Durabula”), even the deepest impressions can be effected with an enormous saving of time and material and in a most practical manner, as will be seen on comparing figs. 69 a to d.
In order to get the full value out of this machine, some little practice is necessary on the part of the workman in charge. But possessed of an average amount of skill, he can soon turn out with this apparatus ten times as much as can be made with the ordinary type of lozenge machine.
For a favourable accommodation of the different pastille plates, the hurdle diagrammed in fig. 68 (by A. Reiche) is quite excellent. It is manufactured out of one complete sheet of steel, is free from any suspicion of soldering, and entirely galvanised. It thus offers a strong guarantee as regards wear and tear. It may also be advantageously employed as a transporting device.
b) Coated chocolates, pralinés etc.
These delicacies are now held in high esteem, and of late the consumption of pralinés and cheaper forms with imitative contents has increased very considerably.
The designation praliné (properly pronounced prahlin) has been applied to sugar-coated almonds and is derived from the name of a cook in the employ of Marshal du Plessis, which was Pralins. This “chef” belonged to the age of Louis XIV. and was the first to make these sweetmeats. But now the term is applied to sweetmeats of various forms, soft fruit-sugar, marmalade, cream, nut-paste etc. respectively enveloped in chocolate. The special formulae employed in the preparation of different kinds of pralinés are comprised in the confectioner’s art, and do not need to be dealt with here.
The substances themselves are called fondants. Formerly the sugar was boiled, placed upon a slab, and there manipulated with a spatula, an operation difficult to manage, indeed almost impossible in the last stages. In consequence of the increased demand for such preparations, machines were introduced several years ago whereby the operation is mechanically performed. Such a machine is shown in fig. 70.
Fig. 70.
The bed-plate as well as all the working parts of the machine are constructed of stout copper. The working parts admit of being raised or lowered by means of the hand-wheel above, and they remain fixed whilst the bed-plate turns and its underside is played upon by water. The machine is capable of working up pure fondant without any syrup addition, as well as that made up with syrup. The boiled sugar is poured on the bed-plate of the fondant machine, cooled down from 10-20 minutes according to the syrup content, and to such an extent that the machine can be set in motion, whilst the working parts are gradually lowered to the previously mentioned bed-plate. The sugar poured out is then cooled by means of the action of a ventilator fitted on a crossbeam, occurring in the middle of the wooden cooler, and working in conjunction with the ventilator, in consequence whereof a cooling current of air is brought to strike the hot sugar centrally.—When pure sugar is used, the fondant is finished within six minutes, but in the case of a syrup addition the time required is lengthened.
Fig. 71.
A quite recent type of fondant machine is given in fig. 71. It achieves its end by employing an air-current and a cylinder with screw, which is provided with water cooling apparatus. The modus operandi presents many and obvious advantages, chief among which is the possibility of conducting new material to the machine uninterruptedly, and further the preservation of the flavour of the chocolate worked up. The result is a production of first-class quality in respect to taste and flavour, which is quite ready to be passed on to the next processes.
Fig. 72.
The fondant is then diluted with colouring matter in boiling pans, and so prepared for subsequent treatment. The figures which have to be poured in are then transferred to gypsum moulds, lined with starch powder, and the fondant sugar is in its turn poured over these either by means of pans held in the hand or such as are machine-driven. Hand-pouring postulates a considerable amount of skill on the part of the man in charge, especially when even weights of the separate pieces are required. We annex an illustration of a motor-driven depositing machine (fig. 72).
The sugar is here introduced into receivers heated by means of a water-bath. The receiving boxes are moved under the outflow one after another, after having been dusted with powder and filled with chocolate, whilst the adjustment of the weight of each separate piece is effected by the operation of a very ingenious mechanism, even from 0-8 grammes.
Fig. 73.
After a stay of several hours in the drying room, the molten figures are so hard that they can be raised out of the powder with the aid of a shovel. Fig. 73 shows such a machine, whilst Fig. 74 illustrates a machine where the work goes on unbrokenly, and from which the chocolate figures are removed with a shovel.
The sweetmeats are next dipped into liquified chocolate (covering stuff) to coat them with a layer of that material. The mass employed for this purpose must contain up to 15 % more butter than that used for ordinary chocolate, so that it may be kept soft long enough for continuous working.[121] This is performed in the machine fig. 75. On a bed-plate coming into contact with steam or cold water, as required, occur rake-like stirrers, and a small ventilator introduced above assists in cooling off the material. For the purpose of discharging, there is an outlet on the rim of the pan. For storage of the tempered coverings and also for occasional alleviations with cacao butter, a machine illustrated in fig. 76 is utilised.
Fig. 74.
Fig. 75.
Fig. 76.
The dipping of pralinés for the purpose of coating them was formerly carried out by means of a fork, the nucleus masses being dropped into the coating material, taken out with a fork, and placed upon metal plates. Various kinds of ornamentation were designed by the same instrument. In the preparation of the higher priced coated fondants, a similar method of procedure is still in vogue, although such manipulation presupposes a high degree of skill on the part of the mechanics are at the machine. For articles of more general consumption, whether ornamented or not, machines have been introduced for the purpose by divers manufacturers, some of which function excellently. Two of that kind which in every way respond to the calls made on them are here described, but we shall not waste time and labour over the more complicated and expensive machines.
Fig. 77.
Fig. 78.
The first method of coating fondants, patented by A. Reiche of Dresden-Plauen, is not based on mechanical principles, but rather relies on a series of small appliances, represented in fig. 77. The jacketed casing a, fig. 77 contains water, and into it the pan containing coating material can be placed: that is kept in a liquid condition by heating the water in the jacket by spirit lamps or gas jets underneath. The adjoining vessel b is closed on all sides, filled with water, and also kept warm in the same manner; it serves for the preparatory warming of the objects to be coated, which are spread upon a wire network, and for that purpose two of these wire frames can be hung upon the hooks inside the box. The mass dropping from the wire frame is conveyed into the covering box a, by means of a sheet of metal placed above it; c serves as an apparatus for turning, and we give it on a larger scale in fig. 78.
Fig. 79.
The tracings h and i in fig. 79 show the cross section and top view of the wire gratings, on which cylindrical and ball-shaped sugar goods are deposited. The other two kinds of grating are illustrated at L and M (fig. 80).
The size of the meshes of the sieve gratings depends on that of the centres to be coated.
The method of covering is as follows:
The centres for the pralinés etc. are placed in the cavities of the gratings, and, as soon as one of the gratings is full, the latter is covered up by the fine-meshed grating the half of the cross-section of which is shown in Fig. 79 and the full view in Fig. 80 (see K and N respectively), K representing the cover-grating.
Both gratings are held simultaneously by the operator at their handles and then dipped together in the liquid covering contained in the vessel a, Fig. 77, after which the superfluous covering mass is removed by knocking. The gratings are now deposited on the mechanism C, Figs. 77 or 78, as the case may be, the top sieve removed and a sheet of paper or a metal plate put in its place. It is then turned by hand to the opposite side, the grating with the impressions is removed and the cover centres are found lying in regular order, and at regular distances apart, on the metal plate. The object of the intervals between the covered centres is to prevent the running together of the latter.
Fig. 80.
Beans and rings are only dipped up to the middle, and the process repeated with the other half of the centre after the first half has cooled. This ensures a pleasing, round appearance, and has further the advantage that the cover grating need not be put on during the operation. When dipping cylindrical or ball-shaped centres, the grating K which has first been removed on dipping, is at once transferred to the heater, to prevent it cooling and withdrawing too much warmth from the covering material at the next immersion.
The dipping of pralinés etc. is exceedingly easy if the new type of dipping machine is used, a full view of which is given in Fig. 81 and which has the highly appreciable advantage of simultaneously cooling the dipped centres. All the parts are, in the main, worked by hand, only the shaking and stirring contrivances and the cooling fan requiring to be driven by motor power. The middle piece carries the actual dipping apparatus, underneath which the tank holding the covering chocolate is fixed, while the lefthand sidepiece serves for feeding; as many as four operators can be engaged simultaneously at the latter, the work consisting of laying the centres in the gratings corresponding to the mouldings desired. The construction of these gratings is, in the main, similar to the stamped trays of Anton Reiche, but they are not provided with handles and are despatched along the guide-rails by hand. The filled grating is then placed in a frame, which is dipped by means of a winch into the liquid chocolate. The top grating on the dipping frame is adjustable, and the object of this grating is to keep the centres down, as without this arrangement some of the centres might rise to the surface of the covering. The top grating is, before commencing to dip, pushed over the filled grating with the centres and is thus immersed with them. The frame having been removed, the shaker is put in action to remove the superfluous material from both the gratings and the centres. The grating is drawn out after use from below the top grating and transferred to a book-shaped ejector, on one side of which is a metal sheet covered with paper. The whole of the centres are then discharged on to the sheet, by reversing the two flap-sections.
The sheet containing the covered centres is then transferred to the cooling apparatus at the right, in which it is gradually lowered on a “paternoster” apparatus by turning round a handle. It is then conducted to the left by an endless band, and finally discharged in a cooled state by the machine. The ventilator should be supplied with air from the cellars and is arranged to blow it out in the opposite direction to the goods in the cooling apparatus.
Fig. 81.
The shape of the design-gratings is reproduced in high relief on the goods, and it will therefore be readily understood that further designs or fancy shapes can be made on the gratings. For the production of semi-dipped goods or such as are dipped round and remain uncovered at the bottom, a device is attached to the striking gear which renders it possible to regulate the depth of each immersion at will. The tank containing the covering material is surrounded by a water-jacket, which is heated by steam. The heat of the water is indicated by a thermometer. The receptacle containing the covering can easily be drawn out towards the front. In addition to this, the whole of the outside of the machine, which also constitutes a complete water-jacket, is heated by steam, and finally the ejector. The gratings containing the impressions are taken out of the ejector after use and transferred to the feeding side to be used again, so that, at the very most, four gratings are required for each design.
The daily output of the machine is 300-600 kilos, and the size of the gratings 280 by 400 millimetres, the output naturally depending on whether the machine is operated by two, three or more persons.
[B. The Manufacture of Cocoa Powder and “Soluble” Cocoa.]
a. The various methods of disintegrating or opening up the tissues of cacao.
The comparatively high fat content of pure cacao, which would deter certain persons, especially those suffering from stomach disorders, from taking it, has given rise to the now extensive demand for a cacao preparation containing a less amount of fat and the constituents of which are capable of being easily assimilated in the human organism. At the same time the desire to obtain a cacao preparation easily capable of complete and uniform suspension in milk or water may have played its part, as this quality, in consequence of which the preparation can rapidly and without difficulty be rendered ready for consumption, is obviously a great advantage. The best way to obtain this appeared to be the pulverisation of the cacao, which, when reduced to a powder, more readily satisfies the above conditions. As, however, it was not possible to pulverise cacao which still contained its full amount of natural fat, it became necessary to devote attention to the operation of extracting the cacao butter. It is many years since the first appearance of certain preparations in Germany which went under the name of “Cacogna”, and which had been deprived of their fat to the extent of 20-25 %. This problem, however, was recognised and attempts and all manner of experiments made to solve it at a much earlier period in Holland. The founder of the well-known Dutch firm of J. C. van Houten & Sons in Weesp, Mr. C. J. van Houten, was the first to attempt the expression of the fat from cacao (1828) and to treat it with chemical agents with a view to opening up or bringing about the disintegration of the tissues, in order to render the cacao a fit and welcome article of food, not only for healthy persons, but also for invalids and convalescent persons.
It was not until the Dutch cocoa thus manufactured had been introduced into England and Germany, where, as well as in Holland, it became very popular, that manufacturers in Germany and Switzerland began to devote their attention to the treatment with chemical agents. The consumption of so-called “soluble” cocoa has increased to such an extent of late years that it is now almost as large as that of chocolate goods.
The term “soluble”, as now generally applied to cocoa powders, is undoubtedly a misnomer, inasmuch as such preparations are practically not soluble at all. We have therefore termed cocoa for drinking purposes in this book “disintegrated” cacao, as the processes described in the following pages only render the elements of cacao, as, for instance, the cellulose, capable of suspension in liquids. It would be quite impossible to render cacao, by any special treatment, soluble in the real sense of the term, as is the case with salt or sugar. It will thus be readily understood that the expression “disintegrated” is correcter and more logical than the term “soluble The degree to which disintegration has been carried, i. e. the efficiency of the opening-up processes adopted, is marked by the absence of any sediment worth speaking of in the beverage prepared with boiling water, even after it has been left standing some time. The greater the power of suspension of the preparation, the less particles of cacao will settle to the bottom, and the higher the beverage will be esteemed.
The disintegrating agents are, in practice, applied either to the raw or roasted, but otherwise untreated beans, or to the more or less defatted cacao, as follows:
a) by treating the cacao with hot water, without or under pressure;
b) by treatment with alkalis, such as carbonate of kali or sodium, carbonate of magnesia (Dutch method), spirits of ammonia (sal-ammoniac) and carbonate of ammonia (German method).
The chemical and physical effects brought about by these agents consist chiefly in the swelling or steeping of the cellulose by the action of the alkalis, as a consequence of which they sink less rapidly in liquids than would be the case with untreated cacao. A further effect is the partial neutralisation of the acids present, besides which the cacao-red or pigment is also attacked, a result which may be regarded as less desirable, as the cacao-red is the secreter of the aroma, which naturally suffers with it. If the cacao is treated with steam or hot water, the starch is apt to gelatinise, and the acids to begin to ferment.
As the treatment with steam, for the reasons given above, is nowadays rarely practised, we will at once proceed to consider the method of disintegrating cacao most in use. Modifications of the methods of manufacture bearing on this point will be dealt with in their place under the corresponding heading later in this book.
b. Methods of Disintegration.
1. Preliminary Treatment of the Beans.
The method of manufacture of disintegrated cocoa comprises the following operations:
- a) The cleaning and sorting of the raw bean;
- b) Roasting;
- c) Shelling, breaking and grinding;
- d) Treatment with alkalis or water;
- e) Expression of the fat or cacao butter;
- f) Pulverising.
The order of the above processes is subject under certain conditions to various modifications arising from the fact that the alkalis are applied at various stages in the course of manufacture, i. e.:
- I. before roasting;
- II. during roasting;
- III. after roasting,
and further
- a) before pressing;
- b) after pressing (treatment of the defatted beans).
The cleaning and sorting of the raw beans, or, in short, the complete treatment to which the raw cacao is subjected (a to c) is in all methods effected by the same machines, a description of which has been given on pages [Transcriber’s Note: Rest of line missing]
Some manufacturers proceed at once to treat the cacao with alkali on completion of the above operations.
C. Stähle[122] effects the disintegration of cacao by subjecting the beans to the chemical action of a mixture of ammonia and steam, at a temperature not exceeding 100 Deg. C. The next process (roasting) is then supposed to draw out the ammonia introduced into the material, which, being volatile, easily escapes, and enables the flavour to develop.
Pieper[123] moistens the raw beans with water, to which alkali has been added, and this has the effect of neutralising the acids present in the bean; afterwards the beans are fermented, dried and roasted. The fermentation is described as rendering the particles of albumin or protein bodies easily digestible and further imparts to the beans a fine, reddish brown colour. This process is therefore nothing but an after-fermentation of the cacao under the influence of alkalis. From a scientific point of view, the process does not possess the advantages which Pieper claims for it, with the exception of the really evident improvement in colour. This effect can, however, be obtained equally well by suitable treatment with water alone.
G. Wendt[124] has patented a method of improving the colour and facilitating the disintegration of cacao, in which the beans are treated, before roasting, with lime water and milk of lime (lime solutions) and further washed with the solution during roasting.
We now turn to the methods of disintegration by means of fixed alkalis (carbonate of magnesia, potash and sodium) first employed by the Dutch, concerning which the following description will be useful.
The cleaned beans are first very superficially roasted, to facilitate winnowing, and the cacao thus treated (half roasted cacao) broken as small as possible, which is an equally important factor in the shelling and winnowing processes. It should be observed here that the less the cacao has been roasted, the finer it should be broken. The material is then impregnated by one of the above-mentioned alkaline solutions, which is sprayed on to the beans. The chief agent employed is potash (carbonate of potassium) in the proportion of 1½-2 (3 at the outside) parts of potash to 20-30 parts of water, for every hundred parts of the defatted material to be treated. Some manufacturers use sodium or a mixture of sodium and carbonate of magnesia in place of the potash. As soon as the cacao has been uniformly impregnated by the alkaline solution, the roasting process should be completed. Still more care should be devoted to the roasting of cacao for pulverising than is required in the case of eating chocolates, as taste and smell play a more important part and the point of complete roasting is not so easily recognised. The cacao being roughly broken and the shells removed, the second roasting process must of course be conducted over a low fire. The most suitable machines for this purpose are the large roasting machines illustrated on page 93, Fig. 14, as in these machines there is little possibility of over-roasting, even when dealing with large quantities and the machine is intensely heated; another advantage is the easy accessibility of the roasting drum, which can be immediately exposed by removing the front cover, for cleaning; cleaning is very necessary in roasting machines. Broken and moistened cacao chars much more readily than raw beans which have not been deprived of their shells. If it is not possible to thoroughly clean the interior of the roasting drum, as is often the case with spherical roasters, the particles of cacao remaining in the drum continually undergo re-roasting, finally falling in a completely charred state into the cacao, thereby greatly prejudicing its taste.
If necessary, the cacao can now be passed through the breaking machine again, from which it is transferred to the triple cacao mill, which provides for fine grinding. The material is then deposited in heated pans (see page [117], Fig. 27) where it remains until ready for the next process, the expression of the fat. The object of the fine grinding in the mill is to render the cacao on being ground again after the defatting process, easily capable of being sifted, and to obtain a preparation which, on being mixed with hot water, leaves as little sediment as possible.
2. Expression of the Fat.
Hydraulic presses are nowadays exclusively used for this most important operation in the manufacture of “soluble” cocoa. The methods of pressing have, in common with the other operations in the course of manufacture, undergone considerable modification and improvement.
According to Macquer (see Mitscherlich, S. 58) the butter was extracted during the last century by pulverising the seeds, boiling them in water and cleansing the fat, which, on cooling, congealed on the surface of the water, by re-melting. According to Desprez (see Mitscherlich, S. 58), burned, shelled and finely pulverised beans were spread to a height of 12-15 inches on coarse linen or canvas, which was spanned across a vessel containing boiling water, to expose the fine powder thoroughly to the action of the hot vapour. The powder was then pressed, in linen bags, between two tin plates, whereby some 50% of pure cacao butter was obtained. At a later period the heatable hydraulic pot-presses came into use. The mass had, however, to be introduced into these pots tied up in a cloth or sack, to facilitate which it was previously treated with water, forming a thickish syrup very convenient for pressing. All these methods, however, were attended with the great disadvantage that the cocoa, after being stored some time, acquired a grey colour, or became mouldy. To avoid these undesirable results presses were constructed which rendered it possible to liquefy the mass without any further treatment in the receptacle in which the pressing was conducted. Such a press, likewise acting hydraulically, is shown in Fig. 82 on the opposite page.
This machine exerts a total pressure of 320000 kilogrammes and works with 400 atmospheres. The construction of the machine is similar to that of the well-known types of presses used by oil manufacturers for the preparation of vegetable oils. When pressing, however, the pots containing the cacao must be rendered water-tight both at the top and bottom, to prevent the liquid cacao from escaping, while such provision is not necessary in the case of the oil presses. The stopping up of the press-pots is effected by means of a side-handle, and arrangements are provided for heating the pots both from above and below. The machine illustrated has 4 pots, arranged one above the other, which can be drawn out on guide-rails towards the front of the machine. During pressing, they close telescopically with the piston arranged underneath each pot. The pump which supplies the water for the hydraulic pressure, works perfectly automatically, increases the pressure according to the quantity of fat which has run off and keeps the pressure at its maximum or at any degree required. With these presses it is possible to extract, without difficulty, 85 % and even more of the total fat of the cacao bean. If pressing is carried on at too high a temperature, a pale, whitish grey butter is the result. If, however, a little attention is paid by the operator at the press, the butter obtained is usually perfectly clear, as it is first conducted through a horse-hair pad covered with linen, or a camel-hair cushion 15 millimetres in thickness. Sufficient attention is not always paid to the operation of pressing, so that it often happens that some of the cacao escapes with the butter, which is especially the case if the pressure has been increased too rapidly at the beginning. If the butter is extracted for use in the factory itself, the escape of the cacao with it is of no serious consequence; if, however, the butter is intended for sale for commercial purposes, its appearance is a most important factor, wherefore it is advisable to filter the impure fat immediately after pressing. It is true that, in most factories, the butter is in such cases merely remelted to allow the impurities to settle to the bottom, this part being then submitted again to the same treatment, while the rest of the butter is disposed of on the market. If filtering is necessary, the butter filter should be used, which, first constructed in Holland, has been in use for a long time there. The principle of these filters is to pass the butter through hanging tubes made of a filtering material similar to flannel.
Fig. 82.
The firm of Volkmar Hänig & Co. constructs special cocoa butter filters which can be obtained through the firm of J. M. Lehmann. Figs. 83 and 83a show this type of filter (cross and vertical section), the manner of working with it being the following:
As soon as the butter has passed through the hair sieve in the upper part of the apparatus, which removes larger objects such as pieces of wood etc., it enters the hanging filter tubes, which, to facilitate cleaning, are interchangeable. The filter butter accumulates in the large space provided for the purpose and is withdrawn through a tap. An observing glass is attached to the apparatus for the purpose of watching the height of the butter, and the whole filter is water-jacketed, the water being heated by a steam coil fixed in the bottom of the apparatus. A thermometer is fixed to the side of the filter, for regulating the temperature.
Figs. 83 and 83 a.
The degree to which cocoa powders should be defatted is an important question which, some years ago, formed the subject of much controversy. The relation between the percentage of fat contained in the original cacao kernel, the expressed butter and the defatted cacao mass is shown in tables 19 and 20.
The taste of defatted cacao is, as is well known, all the better for being defatted to a low degree, and it is this which constitutes the great advantage of cocoa prepared according to the Dutch method, the remaining cacao content of which is some 24-33 percent, so that, taking 50 percent as the average quantity of fat contained in the cacao, only about 34-52 percent of the whole is removed from the mass.
Table 19.
Percentage of butter to be extracted.
| Percentage of fat to remain in the finished cocoa powder | Fat content of kernel | |||||||
|---|---|---|---|---|---|---|---|---|
| 50% | 51% | 52% | 53% | 54% | 55% | 56% | ||
| Weight of butter to be expressed (in proportion to the whole mass) | ||||||||
| Fatty Cacao | 33% | 25·4 | 26·9 | 28·4 | 29·8 | 31·3 | 32·8 | 34·4 |
| 32% | 26·5 | 27·8 | 29 | 30·9 | 32·4 | 33·3 | 35·3 | |
| 31% | 27·5 | 29 | 30·4 | 31·9 | 33·3 | 34·8 | 36·2 | |
| 30% | 28·6 | 30 | 31·4 | 32·9 | 34·3 | 35·7 | 37·1 | |
| 29% | 29·6 | 31 | 32·4 | 33·8 | 35·2 | 36·6 | 38 | |
| 28% | 30·6 | 31·9 | 33·3 | 34·7 | 36·2 | 37·5 | 38·9 | |
| 27% | 31·5 | 32·9 | 34·2 | 35·6 | 37 | 38·4 | 39·7 | |
| 26% | 32·4 | 33·8 | 35·1 | 36·5 | 37·8 | 39·2 | 40·5 | |
| 25% | 33·3 | 34·7 | 36 | 37·3 | 38·7 | 40 | 41·3 | |
| Non-Fatty Cacao | 24% | 34·2 | 35·5 | 36·9 | 38·2 | 39·5 | 40·8 | 42·1 |
| 23% | 35·1 | 36·4 | 37·7 | 39 | 40·3 | 41·6 | 42·9 | |
| 22% | 35·9 | 37·2 | 38·5 | 39·8 | 41 | 42·3 | 43·6 | |
| 21% | 36·7 | 38 | 39·2 | 40·5 | 41·8 | 43 | 44·3 | |
| 20% | 37·5 | 38·8 | 40 | 41·3 | 42·5 | 43·8 | 45 | |
| 19% | 38·3 | 39 | 40·7 | 42 | 43·2 | 44·5 | 45·7 | |
| 18% | 39 | 40·2 | 41·5 | 42·7 | 43·9 | 45·1 | 46·3 | |
| 17% | 39·7 | 41 | 42·2 | 43·4 | 44·6 | 45·8 | 47 | |
| Diminution in value K. | (16%) | (40·4) | (41·7) | (42·9) | (44) | (45·2) | (46·4) | (47·6) |
| (15%) | (41·1) | (42·4) | (43·5) | (44·7) | (45·9) | (47·1) | (48·2) | |
Table 20.
Percentage of butter remaining in the finished cocoa powder.
| Weight of butter to be expressed, in proportion to the whole mass | Fat content of kernel | |||||||
|---|---|---|---|---|---|---|---|---|
| 50% | 51% | 52% | 53% | 54% | 55% | 56% | ||
| Fatty Cacao | 30% | 28·6 | 30 | 31·4 | 32·9 | 34·3 | 35·7 | 37·1 |
| 31% | 27·5 | 29 | 30·4 | 31·9 | 33·3 | 34·8 | 36·2 | |
| 32% | 26·5 | 27·9 | 29·4 | 30·9 | 32·3 | 33·8 | 35·3 | |
| 33% | 25·4 | 26·9 | 28·4 | 29·9 | 31·3 | 32·8 | 34·3 | |
| 34% | 24·2 | 25·8 | 27·3 | 28·8 | 30·3 | 31·8 | 33·3 | |
| Non-fatty Cacao | 35% | 23·1 | 24·6 | 26·2 | 27·7 | 29·2 | 30·8 | 32·3 |
| 36% | 21·9 | 23·4 | 25 | 26·6 | 28·1 | 29·7 | 31·3 | |
| 37% | 20·6 | 22·2 | 23·8 | 25·4 | 27 | 28·6 | 30·2 | |
| 38% | 19·4 | 21 | 22·6 | 24·2 | 25·8 | 27·4 | 29 | |
| 39% | 18 | 19·7 | 21·3 | 23 | 24·6 | 26·2 | 27·9 | |
| 40% | 16·7 | 18·3 | 20 | 21·7 | 23·3 | 25 | 26·7 | |
| Diminution in value K. | 41% | (15·3) | 16·9 | 18·6 | 20·3 | 22 | 23·7 | 25·4 |
| 42% | (13·8) | (15·5) | 17·2 | 19 | 20·7 | 22·4 | 24·1 | |
| 43% | (12·3) | (14 ) | (15·8) | 17·5 | 19·3 | 21·1 | 22·8 | |
| 44% | (10·7) | (12·5) | (14·3) | (16 ) | 17·9 | 19·6 | 21·4 | |
| 45% | — | (10·9) | (12·7) | (14·5) | 16·4 | 18·2 | 20 | |
| 46% | — | — | (11·1) | (13 ) | (14·8) | 16·7 | 18·5 | |
| 47% | — | — | — | (11·3) | (13·2) | (15·1) | 17 | |
| 48% | — | — | — | — | (11·5) | (13·5) | (15·4) | |
Fig. 84.
Fig. 84a.
If the expression of the butter is carried to a further degree, the cacao will certainly become more easily capable of suspension in liquids[125], but such treatment is detrimental to its flavour[126], which is apt to become woody or bitter. The statement, made by certain manufacturers and would-be connoisseurs, that the bitter taste peculiar to the acid produced in cacao during fermentation is the real aroma of the cacao, is undoubtedly erroneous. It could, in the same way, be said of tea and its acids, the bitterer, the better; which would of course end in the destruction of the true flavour. Equally erroneous is the theory that bitter cacao is more consistent. Such cacao must, previous to consumption, either be more sweetened than usual or, if the same quantity of sugar is put in, less of the beverage can be taken. When, for instance, very thin coffee is made, the beans, on colouring an abnormally large quantity of water, are said to be stronger, i. e. to yield more. The consistency of all such beverages is, however, only a matter of taste, and it would therefore be useless to discuss the subject in detail; some persons prefer strong tea, which has been brewed a quarter of an hour, others simply pour boiling water over the tea leaves and then drink the beverage immediately. It may, however, safely be taken that the highest amount of butter which can be expressed from cacao without prejudicing the flavour of the finished powder is 66 percent of the total fat content. Manufacturers nowadays try as a rule to express as much butter as possible, as the butter has a high price on the market, and this tendency naturally has the effect of lowering the quality of the cocoa. We thus come across cocoa powders containing only 20, 17, 15 percent of fat and even less. Of course nothing can be said against the production of such cocoas, provided they are sold at a lower price than cocoas more rich in fat and the public are aware that they are purchasing a non-fatty preparation, besides which the expression of so high a percentage of the fat alone rendered cocoa a fit regular beverage for certain classes of invalids and persons suffering from disorders of the stomach. The only serious drawback in this case is the great variability of the fat content, which fluctuates between 13 and 35 percent. Such fluctuations are absolutely impossible in the case of any other article of food which is manufactured and sold wholesale, or, at any rate, buyers know in all such cases exactly what they are purchasing; this is a point to which serious attention must be called. It is very much to be regretted that the Association of German Chocolate Makers[127] has declined to follow up this matter, while the Union of German Food Chemists, after considerable controversy, advocated a distinct legal classification of non-fatty cocoa powders containing up to 20 per cent. of fat.[128] We would prefer the Dutch preparations, which have remained the same up to the present day, so-called fatty cocoas containing more than 25 percent of fat, to be classified specially and those preparations which contain less than this percentage of fat to be termed “highly defatted” or “dry” cocoas, the names applied to both kinds being of little importance as long as the public has the means of clearly recognising the distinction (see tables [19] and [20]). Some 17 percent must be taken as the minimum permissible butter value, which would mean the expression of about 80 percent of the total fat content, or two-thirds of the cacao mass itself; cocoa powders with only 15 per cent. or less of butter are to be regarded as inferior in quality and should not be produced. Unfortunately, however, these suggested limits are, at any rate for the present, not likely to be realised.
Fig. 84b.
Fig. 85a.
The pressure obtained by means of the pressing devices above described is naturally not sufficient for the production of such highly defatted cocoas. Stronger presses are therefore necessary, one of which, a very powerful apparatus, is shown in Fig. 84.
This machine, at the present time the most powerful cocoa butter press in the world, brings a pressure of over one million kilos to bear on the cacao mass, working with 400 atmospheres, and thus renders it possible to express as much as 90 percent of the total fat content of the bean. The construction of this press is exactly the same as that shown in Fig. 82, the pump Fig. 84a having, however, three pistons or plungers instead of one; it works, like the other machine, automatically, i. e., after the large quantity of water required at the commencement has been fed into the press, the large plunger is put out of gear at a pressure of 5 atmospheres; the two smaller pistons are then put into action together, and produce the enormous pressure of 400 atmospheres.
Fig. 85b.
After defatting, the expressed cacao cakes are allowed to cool down, for which purpose they are transferred to flat trays or other suitable receptacles, and pulverising and sifting the powder thus obtained commenced.
3. Pulverising and Sifting the Defatted Cacao.
There are several methods of proceeding with these operations, such as treating the expressed cacao in the melangeur already described in an earlier part of this book (cf. 30-32 figs.) or passing it through the centrifugal sifting machine (cf. 84b and 88 figs.) with which we are now acquainted. At a time when the melangeur was to a certain extent the universal machine of the manufacturer, it was almost exclusively utilised for pulverisation, that up-to-date division of labour whereby this machine is limited to mixing (and very properly so limited, as its name implies) and the preparation of cacao powders on the contrary assigned to more efficient constructions having then not as yet been adopted. We annex a description of one or two specially constructed arrangements for the pulverisation and sifting of cacao, as manufactured by J. M. Lehmann and already repeatedly tested.
Fig. 86.
First there is the cacao cake crusher (figs. 85a and 85b), which reduces the pressed cake into rather large pieces about the size of a walnut, previous to its being pulverised either in the melangeur, centrifugal sifting machine or some similar apparatus. It has been furnished with one (fig. 85a) and in some cases even with two (fig. 85b) pair of toothed or cogged rollers, and the cacao in this latter type of construction is crushed as small as a pea, which reduction, although it is by no means essential, considerably relieves the strain on the pulverising machine and is also in some sort a protection against unnecessary waste of material.
Fig. 87.
Then again, there is the so-called pulveriser shown in fig. 86. This is in principle an edge-mill with revolving bed-stone and runners, both made of granite. The coarsely broken press cakes are fed into the mill through a hopper provided with a slide, and are reduced to a loose powder of firmly fixed colour, escape of dust being prevented by the hood fitted to the mill. By turning a crank, a lateral sliding door is opened, and an arrangement inside is set in motion, by which the ground cacao is turned out of the mill. The pressure of the runners can be diminished and even completely nullified.
For cacao that has been thoroughly defatted (“dry” cocoa), the hardness of which demands a more efficient treatment than is possible in these machines, they being only calculated to press or at the most exert a rubbing effect, there are the crushers proper, called mills built in pulverising plants for dry cocoas as illustrated on fig. 87.
The pressed cacao, already broken up to some extent in a preliminary crusher (cf. figs. 85a and b), is systematically conducted through the mill by an elevator provided with hopper and feeding apparatus. On the interior of the machine, which is completely plated with steel-plates, there is a cross-arm as on a windmill, which passes through a large number of revolutions per minute. Chiefly owing to its thrashing effect, the cacao in the mill is fine ground, without any rubbing or exertion of pressure as in the melangeur and other machines. The outer part of the frame consists of a grating with various widths of hole, which can be readily changed. The whole of the powder which has attained a certain degree of fineness falls through these meshes and is so despatched from the machine at once, an additional advantage when comparing this mill with the melangeur, in which all the powder, even that sufficiently ground, must remain till the final discharging, much to the detriment of its flavour and aroma.
Fig. 88.
The powdered cacao next succeeds to the sifting operations, after it has first cooled a little, and for these the centrifugal sifting machines are used in the main. Special care must be taken that such apparatus as is used is not too diminutive to deal with the quantities of cacao introduced, as this is extremely injurious to the machine. It is further to be noted that no type of sifter whatever can yield good results if it has not been especially constructed for dry cacaos.
We have before us in fig. 88 centrifugal sifting machine constructed on one of the largest scales. In this cacao is introduced in the floor of the sieve through a feeder, and by means of an elevator. The sifting cylinder is spanned with silk or bronze gauze, and conceals in its interior a rough sort of preliminary sieve, the purpose of which is to prevent the larger unpowdered pieces penetrating to the silk gauze. There is a ventilator inside this rough sieve, which produces and transmits an air current, so that the meshes are kept open. Under proper guidance it is practically impossible for the machine to break down, although the sieve must be cleansed twice daily, an operation scarcely requiring more than two or three minutes, as it is not necessary first to remove the part under consideration. Because of this easy manner of cleaning, the centrifugal sifter far excels all others, as the plan sifter, the latter generally having to be dismounted before this operation can be proceeded with.
The powder issues from the first outlet of the sieve. There is a second, where both preliminary and cylinder sieve transmit their overflow, and this is then again conducted to the pulveriser in order to be worked up once more. Pulverisers and sifting apparatus can be so combined by means of conveyors and elevators that they work automatically, which is always of immense advantage where a large daily output is in question. But pressed cakes which are to be conducted through the machine in broken pieces must first be treated in a preliminary crusher (cf. figs. 85a and b).
Fig. 88a shows one of the plansieves of the firm Baumeister, and protected by patent, which also finds employment for the sieving of cacao powder.
This machine possesses four round sieves lying one upon another, on which the material to be sieved is moved by a crank driving power just as on a hand sieve, so that the surface of the sieve is fully employed. The sieves possess neither projection nor hauling gear, the sieving is effected without pressure or friction, and the powder is therefore loose and woolly. A brushing arrangement revolves without any mechanism, driven solely by the peculiar movement of the plansieve, under the wholly flat sieves, and this brushing arrangement any cacao powder which may adhere to the sieve and so prevents a displacement of the tension, as far as possible.
Fig. 89.
In the following illustration we give as an example the arrangement of a pulverising plant with pulverisers (cf. fig. 86) for a second time.
The preliminary crusher receives the cakes, and then a conveyor brings the broken pieces along to the elevator, which in its turn feeds the filling box of the pulveriser, the connection between the two being established by a sliding platform. The discharged material succeeds on a landing where it is cooled down a little. A second conveyor brings it to the elevator of the sifting machine. Whilst the fine powder is taken up in barrels collectively introduced under the apparatus, the remainder of the cacao passes along to the conveyor first mentioned, is mixed with other broken pieces of cacao cake, and so returns to the pulveriser.
In reference to the Dutch method of disintegration, mention must be made of the process adopted by Moser & Co. in Stuttgart[129], where the cleansed, shelled and moistened beans are enclosed in a rotating drum, so that they can be subjected to the influence of ammonia and water vapour, produced from a solution of ammonium carbonate, which is passed through the hollow interior of the drum. The beans are then roasted and so freed of superfluous ammonia, after which follow in regular order the processes of grinding, defatting and pulverising.
After this description of the Dutch and other well-known methods of disintegration obtaining in the manufacture of cocoa powder, we shall now proceed to describe such of the remaining processes as seem to deserve mention.
c. Disintegration after Roasting.
The chief difference between the following methods of procedure and the Dutch and other processes previously referred to is that in the former the beans are neither impregnated with alkalis before nor during the roasting, but after it has been carried out, and the impregnation occurs sometimes prior, and at other times subsequent, to the expression of the fat. The several stages of treatment which proceed this process succeed each other in the same order as in the preparation of chocolate, cleansing, sorting, roasting, crushing, shelling and trituration following one after the other. But if the treatment with alkali is to take place before the fat is expressed, the cacao passes from the grinding mill direct to the apparatus in which it is subjected to the action of a solution of potash or some other alkali.
1. Disintegration prior to Pressing.
The system of impregnating the ground but as yet undefatted beans with alkali was first introduced into Germany by Otto Rüger, Lockwitzgrund. The principle features of the Rüger process are similar to those of other methods at present frequently met with, so that a detailed description would seem to be rather superfluous. Melangeurs may be conveniently employed in the treatment of cacao mass in a liquid state with alkalis, such as we have previously described, and illustrated in fig. 86 on page 210.
Fig. 90 a.
As preparing machines for disintegration, the kneading and mixing apparatus shown in working position in fig. 28, page 118, and in fig. 90 a with tilted trough for emptying are specially constructed and patented and quite deserve the popularity they have acquired.
Fig. 90 b.
Fig. 90 c.
Fig. 91 a.
Their construction and method of working are described on page 118. Other well-known machines for the purpose are the “Universal” mixing and kneading machines patented by Werner & Pfleiderer, which are shown in figs. 90 b and 90 c. As regards the general outlines of their construction, it will suffice to refer to the excellent descriptions of the machines which occur in the catalogues issued by this firm. Mention cannot fail to be made, however, of the circumstance that in these machines the evaporation of the alkaline solvent is also effected. The working of the kneading arms facilitates the escape of vapour from the mass and prevents overheating from contact with the walls of the apparatus. Underneath, the trough is provided with a double jacket, that is heated by steam.
To maintain connection of the steam and water pipes whilst the trough is reversed there are two flexible metal tubes. Both are screwed to the fixed pipes. For carrying away the vapour given off there is a tin plate cover to the trough, provided with a charging aperture and a channel inside to catch the moisture collecting on the cover and discharge it. When the machine is to be emptied, the cover is raised and a receiver adapted to the size and form of the machine is so placed that the charge can be diverted into it. The tilting of the machine is effected mechanically, and depends on the working of a lever. So as to prevent spurting of the liquid material when discharging, the stirring arms can be stopped for a time.
From this “Universal” Kneader and Mixer the special type “Vacuum Kneader”, system Werner-Pfleiderer, is distinguished, as its name implies, by a vacuum arrangement. As seen on illustrations 91 a and b, this comprises a pyramid-like cover made of cast iron, and shutting down air-tight, which is provided with indiarubber caulking, and binding screws, and is fitted up for steam heating. It moves on the frame of the machine and is counterpoised with weights, so as to facilitate its raising and lowering. On the front part of the lid there is a small aperture paned in with glass, and opposite on the interior in a specially protected compartment occurs an electric light arrangement, which admits of the continual observation of the material during the working up processes. In addition, small quantities of cacao mass can be introduced on removal of the glass pane without lifting up the lid; so that the advantages of the aperture are twofold. The upper part of the cover tapers off into a suction pipe, which itself terminates in a flanged support intended as a finish to the conduit from the airpump.
Fig. 91 b.
The kneading trough of the machine is made of cast iron, provided with a false bottom, and fitted up for heating with hot water or steam to a pressure of 7 atmospheres, or for cooling down with cold water. By way of rapid discharging, the trough is counterpoised with weights, and can easily be tilted over by means of a hand winch. Its interior, as also the kneading shovels, are clean scoured, and the bearings of the shovels stopped with easily adjustable stuffing boxes. These stuffing boxes (German Patent) are so fitted in that no greasing substances whatever can penetrate to the cacao mass, which is of the highest importance, as in the case of the ordinary stuffing boxes grease is sucked up into the kneading trough by the action of the air pumps and the material contained in this so rendered impure. The steam and water conduit to and fro is effected by means of supple metallic hose, which follow the movement of the trough as it is tilted.
The vacuum kneading machines have acquired great importance in the manufacture of milk chocolates, where it is chiefly a question of reducing mixtures of cacao, sugar, and condensed milk to a requisite thickness. Lately the value of the machine has been regarded as consisting in the main of the possibility of preparing cacao under vacuum which it affords.
It is easy to understand that the treatment of the cacao under vacuum demands a much lower temperature and takes place in about half the time requisite for open machines, where it must be carried out against the constant and contrary influence of the atmosphere, apart from the fact that the vacuum kneader preserves the aroma far better.
The alkali solution used in disintegration may be prepared in vats fitted with draw-off cocks, or, in small factories, in glass carboys such as are used for the conveyance of acids. Of the fixed alkalis, potash is preferable, since it is a natural constituent of terrestrial plants and therefore of the cacao bean, and so its employment introduces no foreign ingredient. Magnesium carbonate seems to find favour in many quarters, but we consider it less suitable as being insoluble in water, and therefore can only be incorporated with the cacao mass in a state of suspension. It is sufficient to have a potash solution some 90 or 95 % strong, answering to the requirements of modern medical treatises.[130] The salt is soluble in an equal quantity of water.
In preparing the solution, the best plan is to dissolve a known quantity in from 3 to 4 times as much water at the temperature of the room and then by diluting with water reduce this composition to the required strength. As for each 100 kilos of cacao still undefatted from 2 to at the most 3 kilos of potash and from 15 to 20 kilos of water are required, this 2 or 3 kilos of the salt should be dissolved in about 10 litres of water and the solution after diluted with the remainder of the water.
In using volatile alkalis, which are nevertheless falling into disuse more and apparently no longer maintain their reputation, ordinary ammonium carbonate which may be easily obtained in powder form at any chemist’s, or a solution of ammonia, such as spirits of sal-ammoniac, may be used. The former is easily soluble in about five parts of water. From ½ to 3 kilograms of ammonium carbonate are generally reckoned for every 100 kilos of undefatted cacao material, and this amount is dissolved in water, the whole of the salt being at once introduced into from 15 to 30 litres, as when smaller quantities are used there ensues a decomposition of the salt and one of the products of decomposition, the carbonate of ammonium, remains undissolved.
The spirits of sal-ammoniac operate much more effectively than the ammonium carbonate on account of their high percentage of ammonia, and so only a third as much of this substance may be employed, and generally even smaller quantities prove quite sufficient. Consequently 100 kilos of defatted cacao should be mixed with 0·5-1 kilo of ammonia solution (specific gravity 0·96), previously diluted with 20 or at the most 29 litres of water. The mixture should be prepared in glass carboys immediately before use, because of the volatility of ammonia.
In the treatment of the cacao, salt solution and cacao are together introduced into a melangeur, or better into the kneading and mixing machine, and the apparatus being set in working order, steam enters, and removes the quantities of water which have been added, as well as the volatile alkalis. Whether all the water has been driven off or no can only be judged from the consistency of the mass after treatment, and it is just this that renders the process of little value. The cacao material issuing from the machine must be just as liquid as when it comes out of the triturating mills, and so long as it appears as a glucose substance, which very often happens where unsuitable mixing machines are employed, so surely will it contain water, and this may lead to the growth of mould or to the cacao developing a grey colour when packed in boxes. If the cacao cannot be sufficiently dried in these machines, it must be transferred to some sort of drying plant (where the temperature is about 48 ° C.), and there deprived of its still remaining moisture.
When volatile alkali is used, kneading and mixing machines cannot very well be dispensed with, as they work up the cacao material much more thoroughly and admit of a better distribution of the ammonia than the melangeur or incorporator. In this case it is advisable that the entire process be carried out in some apartment separated from the other rooms of the factory, in order that the pungent smell of ammonia may not be communicated to other products, a further evil connected with this method of disintegration. At the same time provision must be made for the escape of the discharged gas through flues leading out into the open air.[131]
The treated cacao, when perfectly free from water and volatile alkali, then passes on to the press, pulveriser and sifting machine successively, the several operations being proceeded with exactly as described. In the original process of Rüger’s, the defatted and disintegrated cacao is dried after it has been reduced to smaller pieces, and then mixed with fat in such proportions as seem requisite and desirable, so that it is possible in this method to re-imbue a disintegrated cacao with its original percentage of fatty contents.
2. Disintegration after Pressing.
In this process, which may no longer be adopted as far as we can ascertain the mechanically prepared beans are roasted, crushed and decorticated, then ground in mills, defatted, and finally the cakes are broken up into a rough powder and treated with alkali in the manner above described. Care must here be taken to use as little water as possible in dissolving the alkali. It is best to employ potash exclusively, for it has been found that the last traces of volatile alkali are extremely difficult to remove from defatted cacaos as decomposed by the solution, and there is no means of neutralising the ammonia without at the same time causing material damage to the flavour and aroma of the product treated.
The concentrated solution of alkali may be conveniently sprayed on the powder while the latter is subjected to a constant stirring, an operation best effected in the melangeur. The final drying is carried out in hot closets, provided with an effective ventilator suitable to the purpose. After it has been thoroughly dried, the cacao next succeeds to the pulverising and sifting processes.
Some methods of rendering cacao soluble remain to be mentioned, wherein no alkali whatever is used, and in which the disintegration is effected by means of either water or steam. The first process of the kind was invented by Lobeck & Co of Dresden[132] in the year 1883. The cacao beans, either raw, roasted, decorticated, ground or otherwise mechanically treated are exposed to heat and the action of steam under high pressure in a closed vessel, then subsequently powdered and dried. The process has little to recommend it and has not been able to establish itself accordingly, for hereby the starch in the cacao is gelatinised, and acid fermentation is introduced, such as does not fail to damage the final product. Then again, there is a danger of the cacao becoming mouldy in the store rooms, after being treated by this process.
A second method, patented by Gädke, German Patent No. 93 394, 17 th. Jan. 1895, consists in disintegrating by means of water in a less practical manner. The roasted, decorticated but as yet unground beans are moistened with water, and subsequently dried at a temperature of 100 ° C. after which succeed the processes of grinding, defatting, pulverising and so forth. This process has also failed to establish itself to any effect.
In our opinion any one of these methods skilfully and properly carried out will yield a marketable, hygienic and wholesome product, though some of them can boast of their own particular advantages. This holds good for the so-called “Dutch” method in particular, though it is open to the objection that the cacao so prepared is combined with an extraneous product and that the combination remains right up to the moment of consumption. Considered from this point of view, disintegration with fixed alkalis is generally less advisable than the optional treatment with water or volatile alkali, but it may be taken for granted that each manufacturer had better decide the several details best adapted to his own particular outfit.
A well made soluble cocoa powder should have a pure brown colour, without any suspicion of grey, should be perfectly dry, and feel light and soft when finely divided, so betraying that property which the French designate under the term “impalpable The peculiar aroma of the cacao must be retained, and especially should the preparation be preserved from the slightest taint of any ammonia combination, its taste being kept pure and cacao-like, any hint of alkalinity indicating defect in the manner of disintegration. Over and above delicacy of aroma and taste, that characteristic described as “solubility” constitutes a main criterion of quality in the eyes of the consuming public. To ascertain that only an empirical test can be employed.[133] About 7·5 grammes of cocoa powder are introduced into some 150 grammes of hot milk or hot water contained in a graduated beaker, and then the quantity of sediment which sinks to the bottom of the vessel in a given time is noted. The more slowly a sediment is formed and the smaller it is, the greater the “solubility” of the cocoa.
If it becomes necessary to give the cacao an additional flavouring, the spices or ether-oils generally employed in the manufacture of chocolate may be used in the course of pulverisation, and shortly before sifting.
[C. Packing and Storing of the finished Cacao Preparations.]
Chocolate will keep in its original condition for years, when protected from atmospheric influence. It is therefore generally, and especially where the finer qualities are concerned, packed up immediately after it leaves the last process, and ornamented chocolates are previously varnished with an alcoholic solution of benzoin and shellac (see page [250]).
The inferior qualities are usually packed in paper and wooden boxes, but the superior first in tin-foil and subsequently in paper. Cocoa powder arrives packed in parchment boxes as a rule, and also in cardboard or tin boxes.
Although packing in parchment or waxed paper is hygienically and economically more advantageous than tin-foil packing, the latter is nevertheless to be preferred, not only because it is a better preservative of the aroma evident in the spices added, but also because it prevents an evil which also in the end leaves its mark on cacao, when stored a very long time, to wit, the development of rancidity. This is explained by the fact that the tin-foil sticks to the chocolate, and so hinders the penetration of air.
According to an act dating from June 25th. 1897, and in force in Germany (Reichsgesetzblatt No. 22), metal-foil containing more than one percent of lead may not be used in the packing of snuff, chewing tobacco and cheese. What holds good for other articles of consumption must also apply to cacao preparations, when they are so packed that they come first of all into contact with metal-foil, and not with paper. Tin-plating also, containing in its coating more than 1 % of lead and in the soldering more than 10 % is also inadmissible in the chocolate industry. Although it is said that the whole of the tin-plate fittings made in Germany are constructed according to an imperial standard, yet it may occasionally so happen that cheap packing material does not correspond and answer to the legal requirements.
The manufacturer can only protect himself against possible prosecution for contravening or neglecting the articles of this act by obtaining a written guarantee as to the quality of the tin-plate supplied.
The rooms where chocolate wares are stored should not be too warm, and it is indispensable that they be kept dry, for heat accelerates the volatilisation of their aroma and also the rancidity to which cacao is liable, whilst moisture spoils the general appearance of the chocolate and promotes the growth of mould. This development of mould, which is first noticeable after long storage in damp, dark warehouses, is principally due to the growth of a fungus which Royer has named “Cacao-oïdium[134]
As the numerous wrappings (in tin-foil, paper, etc.) are at present only effected by hand labour, they mean an appreciable increase in the price of the goods. This is of less moment for the chocolate tablets as the small napolitains and the like. Therefore attempts have often been made to effect this wrapping by means of machines[135], and I have seen among others two models for napolitains, one on a large and the other on a small scale, the property of a Hamburg chocolate factory, and constructed by the firm of A. Savy & Co., Paris, which same machines were said to effect the wrapping in tin-foil, folding and additional packing in paper, as also the final closing, automatically and well; but just as I requested to be shown the machines, I was told that they were for the time being not in working order. Since then I have heard no more of the matter, and regret that the firm of Savy & Co., who have a branch in Dresden, have not been able to answer several letters which I sent them inquiring for further particulars. It must be that the machines have failed to answer their purpose, for otherwise they would have been assured of a hearty reception, no matter how dear they might have been. So for the nonce our chocolate packing must depend on hand labour.
Quite a different arrangement obtains in respect to cocoa powder, which was also originally packed up in paper bags by hand. This operation is to-day despatched in machines, as also in the case of other powder substances, like tooth-powder, dyes, patent foods, soap powder, etc., and this even in the smallest of factories. It is true that the machine built a decade ago by L. Wagner in Heilbronn and at that time described by Zipperer in our second edition, which was to wrap up a dozen packets simultaneously, seems to have failed, for it is no longer constructed; yet its place has been taken by a succession of other machines which have stood the tests of many years. The principle has been altered, many packets at one time not being filled, but always one only, and the advantage lies in the fact that the machine fills more exactly and with a higher degree of uniformity as regards the weights of the several packets.
Figs. 92 and 93.
Apart from the “Machines for packing en masse” Co., Ltd. Berlin, who put out several automatic fillers, special mention may here be made of the firm of Fritz Kilian, whose automatic filler and packer “Ideal” (fig. 92) for quantities of from 25-2500 grammes, and “Triumph” (fig. 93), for quantities of from 1-100 grammes, have both long established their right to a place in every factory, their excellence being predominant.