The machine bakery, however complete, is not likely ever to be quite automatic and continuous like a modern flour mill, where the plant is connected throughout and virtually forms one machine (see [Flour and Flour Manufacture]), and though the engineer has at least managed to effect every operation of the bakehouse by mechanical means, it is not yet possible to shoot a sack of flour into the hopper of the sifter on the top floor, and to turn it into bread, without any human intervention whatever, though as things are, the moulded dough can be put into the oven without undergoing actual contact with human hands. In practice, some of the machines mentioned above are often dispensed with, even in so-called machine bakeries. The flour sifter and blender is indeed found in many bakeries where mechanical kneaders are unknown, while not in all machine bakeries would be found dough weighers and dividers, still less moulding machines. The economical side of the argument on behalf of machinery is presented in the familiar shape that a properly equipped machine bakery can turn out better work at a lower cost (by dispensing with labour), or at any rate can carry on a bigger trade with the same staff. There is plausibility in this argument, but it must be admitted that innumerable bakeries of capacities varying from 10 to 20 sacks per week are carried on more or less successfully without machinery of any kind, beyond perhaps a sifter or blender. Moreover, some of these bakehouses produce bread which can hardly be improved on.
One advantage claimed for flour sifters, besides removing the impurities, is that by thoroughly aerating flour they cause it to become more “lively,” in which condition it kneads more readily. It is also quite possible that the air which is thus incorporated with the dough has a stimulating effect on the yeast, causing a more energetic fermentation. A strong argument in favour of dough kneaders is their hygienic aspect. It is agreed that the operation of dough stirring by hand, since it involves severe labour conducted in a heated atmosphere, must be liable to cause contamination of the dough through emanations from the bodies of the operatives. In well-managed bakeries the utmost personal cleanliness on the part of the staff is exacted, but the unpleasant contingency alluded to is certainly possible. It is also contended that the use of machinery for dough kneading and batter whisking will ensure better work, in the sense that the mass under treatment will be more thoroughly worked by mechanically driven arms of iron or steel than by human limbs, liable to weariness and fatigue. The better worked the dough, the greater its power of expansion, and consequently the greater its bread-making value.
The most widely known machine used in connexion with bread-baking, next to the sifter, is the dough kneadcr. The dough kneader is no new invention. As far back as 1760, a kind of dough kneader was constructed in France by one Salignac. It Dough kneaders. is described as consisting of a trough, inside which the dough was agitated by arms shaped somewhat like harrows. This machine is said to have been tested before a committee of the Academy of Sciences, who reported that in their presence dough had been prepared in fourteen to fifteen minutes. The bread baked from this dough is said to have been most satisfactory, but for some reason the machine never came into general use. For one thing, the power problem would have been almost insuperable to a baker in the France of those days. In general design this kneader approximated to the machines which have since done good work in bakeries all the world over. Salignac was quickly followed by another inventor, Cousin, also a Frenchman, who brought out in 1761, or thereabouts, a dough-kneading machine, which, however, had no better success than its predecessor. The first kneading machine which appears to have been in actual use in a bakery was constructed by a Paris baker of the name of Lembert, after whom it was called the Lembertine. Lembert is said to have been experimenting with this apparatus as early as 1796. Be that as it may, it was not brought out till 1810, when a prize of 1500 francs (£60) was offered by the Société d’Encouragement pour l’Industrie Nationale. This reward was won by Lembert, and his machine thereupon came into a certain amount of use in France. It is remarkable that France long remained the only country in which dough kneaders were employed, but even there their use was limited.
The Fontaine, another French kneader, called after its inventor, was first made in 1835. It had a certain success, but has long passed out of use. It appears to have been a copy to a great extent of the Lembertine. The objection against both these machines was that their blades, while exercising a mixing action, were deficient in kneading effect. Probably the first machine which achieved the task of efficiently replacing the work of human arms in sponge breaking and dough kneading was the Boland kneader. This was also a French machine, and dates back to about the middle of the 19th century. It is believed to have been first used in the Scipion bakery in Paris. It consists essentially of a trough, inside which revolve a pair of blades so arranged as to work somewhat like alternate screws: it is claimed for these blades that their action has the effect of tossing the dough backwards and forwards when it is slack, and of drawing it out when it happens to be stiff. It is further claimed that the blades are so shaped that their revolution has the effect of moving the dough from right to left and left to right in the trough. The machine is geared to give two speeds, the faster being suitable for sponge setting, while the slow and most powerful speed is intended for the doughing. The Boland machine has been widely adopted in other countries than France, and was certainly one of the first dough kneaders to be used in the United Kingdom. It was installed in the great Boland bakery in Dublin, where it proved a great success. The proprietor of this bakery, with which was also connected a flour mill, is said to have had his attention first drawn to this machine by the fact that its inventor was his namesake, though no relative.
The Deliry-Desboves dough kneader, also of French origin, and in general use in France, consists essentially of a cast iron trough, shaped somewhat like a basin, and turning on a vertical axis. The kneading arms inside the trough are shaped after the pattern of a lyre, and have the effect of first working up and then dividing the dough right through the kneading process. Two helical blades, which also form part of the mechanism, serve to draw out and aerate the dough, as effectively, it is claimed, as can be done by the most skilled operative. The force of the kneading operations can be regulated without stopping the machine. A thoroughly kneaded dough can, it is said, be made in this machine in twelve to fifteen minutes.
In Great Britain the type of machine that used to be most in favour was the trough within which the kneading arms worked on horizontal axis. The trough was either open or provided with a lid. The kneading blades were variously shaped, but generally were more or less straight, and were designed to both mix and aerate the dough. In some cases the kneading blades were worked on a single axis, in others two different sets of arms worked on two axes running parallel to one another. Generally the kneader was geared to two speeds, the fast motion being most suitable for sponge setting, and the earlier stages of dough-making, while the slower motion was intended to draw out and thoroughly aerate the dough. To discharge the dough, the trough was tilted by means of a worm and worm wheel, the latter being secured to the trough. Several variations of this type of kneader are still in use. The machine known as the “Universal” kneader consists of a trough set horizontally, within which rotate on horizontal axes a pair of blades lying in the same plane. These blades are curved and are geared together by means of differential spur wheels, with the object of running the two spindles at unequal speeds. The bottom of the trough is divided into two semi-cylindrical cavities, separated by a ridge. Each blade plunges into its own cavity, and the action of these arms tends, while pressing the dough against the sides and base of the trough, to bring it quickly back towards the centre. The differential speed has the advantage of effecting a more thorough mixing of the dough, as it brings together pieces of dough which have not yet been mingled, the blades pushing the dough from one cavity to the other. To hasten the kneading process it is desirable occasionally to reverse the motion by a turn of a hand wheel on the same shaft as the two pulleys. This wheel governs all the motions of the blades. The trough, which is set low, is tilted over, when the dough is ready, by an endless chain operated by a hand winch. The effort required for this operation is very slight, as the trough is balanced by two weights. The action of tilting does not interfere with the blades, which continue rotating until stopped by the hand wheel. The Universal kneader was designed to imitate as closely as possible the action of a pair of skilled human arms and hands, but of course works at a much greater speed.
Another form of dough mixer which is extensively used consists simply of a drum made of sheet steel supported by two A-shaped standards at a sufficient height from the floor to allow a trough to be run underneath to receive the dough when ready for the moulding board. In this drum are two tight-fitting doors. The interior is fitted with no blades or knives, but presents a free cylindrical space, with the sole exception that, set not very far from the circumference, there are several fixed rods passing from one side of the drum to the other. These act as mixers of the dough. The door is opened and the flour and water poured in, whereupon the door is again fastened and the drum is made to rotate. As the rotation proceeds, the dough begins to form, and being lifted up by the revolving drum falls by its own weight. In this process, which is repeated again and again, the dough is caught by and tumbled over by the rods, which act as mixers and take the place of the revolving arms of the trough kneader. The kneading action of the rotating arms is absent, but the steady tumbling over these rods appears to have a thorough mixing effect, and the dough is discharged from the drum in good condition for moulding. The time occupied for making a dough by this apparatus varies from four to six minutes. The advantages claimed for this machine are that it consumes comparatively little power, and that there is not so much danger of “felling” or over-kneading dough as in some of the machines with revolving blades. The compactness of this rotating drum mixer, often known as the Rotary mixer, recommends it on shipboard and in other places where space is limited.
In the earlier days of machine bakeries the accurate dividing of dough, and still more the moulding of loaves by mechanical means, was considered an unattainable ideal. The first step in this direction was made by the Lewis-Pointon dough Dough dividers and moulders. divider and weigher, which was intended for dividing and weighing out dough ready for the moulding table. In an ordinary way a baker who wishes to bake a batch of half-quartern or 2-℔ loaves scales off 2 ℔ 2 oz. of dough for each loaf. The 2 oz. are a sort of insurance against light weight. The evaporation of moisture from dough in the oven is bound to reduce to some extent the weight of the baked loaf, but with normally baked bread, 2 ℔ 2 oz. in the case of half-quarterns, and 4 ℔ 4 oz. in the case of quartern loaves, is sufficient to ensure full weight. As the accurate scaling of dough requires some pains and trouble, it would be surprising if hand scaling were always accurate. The Lewis-Pointon machine can, it is claimed, be set to turn out lumps of dough of the exact weight required either for 1-℔, 2-℔, or 4-℔ loaves. The apparatus does not measure the dough by weight but by volume by an ingenious piston arrangement. The machine when first put on the market was a little complicated, but its mechanism has since been simplified. It has been successfully worked on doughs of all descriptions, ranging from the tightest to those made with 20 gallons of water to the sack. The same firm which brought out this dough divider has also produced a dough-moulding machine, which has a wide range of work. In this apparatus the dough is introduced between a trough and a revolving table at a point on the outer periphery of the latter. The order of things observed in hand moulding is here reversed, as the trough, unlike the hand, is fixed, while the table revolves around a vertical axis. This table is sharply coned, and can be made to work the dough as much or as little as may be required. In working dough for tin or Coburg loaves only one trough is used, but for cottage loaves two parallel troughs are fitted, one taking the lower and the other the upper half of the loaf. In the latter case, a single piece of dough is fed into the machine and passed through an automatic splitter, the two portions being automatically carried into the troughs and simultaneously delivered at the other side of the machine ready to be put together. With doughs which require “handing-up,” two machines may be used for moulding, the dough being automatically fed from the divider to the handing-up machine, and after a short proof passed through the finisher. But the moulding machine may also be used as a “hander-up.”
Another ingenious dough moulder, known as the Baker-Callow, works on a rather different principle. Here the pieces of dough coming from the divider are fed into the moulder by a canvas band, and are worked between a large cylindrical roller and a vertically running canvas and leather belt. To prevent pieces from dropping through, and to assist the moulding process, a smaller roller is placed under and between the cylindrical roller and canvas belt. A wooden puncher also assists in working the loaves, which are finished by being rolled between a band and a special shaped wooden moulding. This machine delivers the dough in spherical shaped pieces. If intended for cottage bread they are at once placed on the dough table at the side, and one piece is put on the top of the other ready for the oven. It is claimed the machine will deal equally well with large and small pieces at the same time, so that the tops and bottoms can be made together. Should the machine be intended for tinned bread, a special attachment is used, into which the spherical pieces are delivered from the machine and rolled into cylindrical shapes, ready to be dropped into the pan. A capacity of sixty loaves per minute is claimed for this moulder.
Ovens.—The ordinary baker’s oven is a vaulted chamber, about 10 ft. in length, by 8 ft. in width and 30 in. in height; it is constructed of brick or stone, and has a small door in front through which the oven is charged (by means of a “peel” or long wooden shovel) and the batch withdrawn. The furnace and fire-grate are often placed at the side of the oven door, but with the oldest ovens, which were heated by wood, there generally was only one door for the fuel and for the bread. Whether the furnace is heated by coal, as is usual in England, or by coke, as is often the case in Scotland, the oven mouth remains in the bakehouse itself; hence the stoking and scuffling must be carried out within the bakehouse. This is in many ways objectionable. For one thing, the fuel must almost of necessity be kept in the bakehouse itself, and it is obvious that the products of combustion are liable to get into the oven. In the old type of oven a flue was frequently placed on the other side of the furnace door, both furnace and flue being on the front of the oven. After firing the furnace, the oven is allowed to “lie down” for a certain time, and secure an even distribution of heat. The furnace and flue are then shut, and the oven charged, the batch being baked by the heat stored within the oven chamber. With ovens of this type, each batch of bread requires a separate firing. This kind of oven has undergone several improvements of detail, but the principle of internal heating, that is, of firing the furnace inside the bakehouse, has remained unchanged.