SOUPS.
Classification of Soups.
—The soups which are commonly consumed are divided into two great classes—those of animal and those of vegetable origin. Any liquid or semi-liquid preparation of a meat or vegetable or the two combined which may or may not carry particles of solid substances is classed with these preparations. Soups are generally used at the beginning of a meal, usually at dinner-time, and, as a rule, do not have any very high nutritive value. That they have a useful function cannot be denied, since the introduction of a small quantity of a condimental and slightly nutritive warm liquid into the stomach at the beginning of dinner tends to stimulate the secretive glands of the stomach walls to greater activity and thus to promote digestion. Soup should be regarded pre-eminently as a condimental and not as a nutritive substance.
Preparation of Stock.
—In the making of stock the base of the material, as a rule, is that part of the meat and bone soluble in hot water. The best way of preparing this stock is as follows:
The meat and bones selected should be fresh, free from all impurities and be derived solely from healthy animals as soon as they have been slaughtered. Inasmuch as the shape of the material used is of little consequence the parts of the carcass that are cut away in the preparation of the usual cuts of the marketable meats are utilized for stock making. The flesh should be cut into fragments of proper size and the bones broken up into small pieces. This material with the appropriate amount of water and salt is placed in a vessel capable of being closed in such a way that no aqueous vapor will escape, and a slight degree of pressure, equal to the half of an atmosphere, can be sustained. Simple forms of digesters are made for this purpose which are perfectly safe at low pressure and supplied with a safety valve so as to allow steam to escape if the pressure runs too high. Several hours of digestion are necessary for the preparation of stock, and if an ordinary vessel is used care must be exercised that the liquid does not evaporate so as to make the mass dry. Stirring from time to time assists the solution of the soluble substances. After the extraction is complete the liquid contents are poured off and the solid material pressed gently to separate the liquid held in solution. The mass is then put in a cool place and allowed to stand until thoroughly cooled and all the fat particles are collected at the top. The fat is then removed and the resulting liquid strained to remove any solid particles. The clear solution thus obtained is set aside and used as stock in the preparation of the various forms of soups. When properly flavored and used by itself it produces the soup known as consommé.
The soup stock made in this way usually contains not less than 95 percent of water and not more than 5 percent of nutritive matter. Many of the clear soups prepared in this way contain very much less nutritive matter, sometimes as low as one percent. It is evident, therefore, that the soup stock is valuable as a condiment and flavoring and not as a food.
The number of soups which can be made from soup stock is practically unlimited. They are formed by the admixture, chiefly of vegetables cut into small pieces, of starchy materials, mashed peas or beans, particles of potato, fragments of parched bread, and in fact almost any nutritive and palatable substance which the cook may wish to employ.
A soup made from a stock of the above description with pea flour was found to have the following composition:
| Water, | 88.26 | percent |
| Protein, | 3.38 | „ |
| Fat, | .93 | „ |
| Ash, | 1.13 | „ |
| Starch and other carbohydrates, | 6.30 | „ |
A soup made with potatoes from stock of the above description was found to have the following composition:
| Water, | 90.96 | percent |
| Protein, | 1.37 | „ |
| Fat, | 1.53 | „ |
| Ash, | .99 | „ |
| Starch and other carbohydrates, | 5.13 | „ |
The French make soups which are very well known and highly valued by cutting vegetables, such as carrots, beets, radishes and other vegetable substances, into small pieces and adding them to the soup stock.
Oyster Soup.
—A soup made of milk, cream, flour, condiments, oysters and the liquid of oysters is very largely eaten in the United States. The difference between oyster soup and oyster stew is chiefly in the amount of oysters employed.
Green Turtle Soup.
—A soup stock prepared as above described and flavored with pieces of green turtle is a very common dish.
Mock Turtle Soup.
—A soup made in imitation of a turtle soup in which veal takes the place of turtle for flavoring is known as mock turtle soup.
Clam Soup or Clam Chowder.
—This is a soup made of clams in the same way that oyster soup is made. When the clams are cut into small pieces and are in great abundance and when potatoes are used in large quantities in the mixture it is known as clam chowder.
Beef Extract.
—It is evident that a beef extract is only a soup or a soup stock specially prepared from beef. Beef extract first became known by the researches of the celebrated chemist Liebig, and has passed from a mere local preparation to an article which is important in commerce. Factories have been established in localities far removed from the principal markets of the world, but where cattle are extremely plentiful, as in South America, and the preparation of beef extract is carried on on a large scale, the meat of the animal being thrown away after the preparation of the extract. The method of preparing beef extract is practically that described for making a soup stock under pressure. Instead of using only the trimmings and refuse of the animal, however, usually the whole of the flesh is employed. The bones are sometimes used in the making of a beef extract. The sound, fresh meat is cut into small pieces and extracted under pressure as already described. After cooking and filtering the product it is brought, in vacuo, to a proper consistence. Meat extract is, therefore, simply a concentrated soup stock. It requires about thirty-four pounds of meat to yield one pound of concentrated extract, and this extract may be diluted for consumption so as to make from six to seven gallons of beef tea. The composition of the ordinary beef extract of commerce shows that it contains from 15 to 20 percent of moisture, from 17 to 23 percent of ash and from 50 to 60 percent of meat bases, that is, the soluble nitrogenous contents of meat. The bones and tendons are not used in making beef extract on account of the introduction of considerable quantities of gelatine into the material. Liebig does not recommend the presence of gelatine in beef extract because, being cheaper in quality, it is an adulteration of the genuine article, which should contain only the pure bases and not the gelatinous principle of the meat in the tendons and bones.
Character of Nitrogenous Bodies in Beef Extract.
—When beef extract is prepared according to the Liebig method those nitrogenous bodies commonly known as meat bases are found in the concentrated extract. In a beef extract which contains a total of 9.28 percent of nitrogen the quantity of nitrogen in the form of nitrogenous compounds which were found therein is as follows: Nitrogen in the form of soluble albumin,—trace; in the form of albumoses,—1.17; in the form of peptone,—trace; in the form of meat bases,—6.81; in the form of ammonia compounds,—.47; in the form of unenumerated compounds,—.83. The chief meat bases which form the principal part of the substance are creatin, creatinin, xanthin, carnin and carnic acid.
There are many different forms of beef extract upon the market, sometimes called by fanciful names and sometimes by the name of the manufacturer. Among the fanciful names are some which indicate origin or kind. The extracts which bear the names of the manufacturers are very numerous, but all of these extracts are essentially of the same character. One of these is a meat extract in which some of the meat fiber is contained. The quantity of meat fiber which is used varies, but is not very great. A comparison of the dry substance in a preparation of the class mentioned above with the dry substance in meat shows the following relation:
| Protein. Percent. | Meat Bases. Percent. | Ash and Mineral Matter. Percent. | |
|---|---|---|---|
| Extract, | 49.7 | 25.6 | 24.7 |
| Meat, | 86.7 | 7.8 | 5.3 |
The above data show that the extract is essentially different in its composition from dried meat and has added to it a large quantity of meat fiber or the meat rendered soluble by some kind of treatment.
Nutritive Properties.
—It cannot be denied that meat extract, as has been said in the case of soup stock, contains only a small part of nutritive matter. This nutritive substance is in a state of solution and probably is more readily absorbed than a similar amount of other nutritives in the form of ordinary meat. Its chief value as a nutrient, therefore, is not in the amount of nutrient material which it contains, but in the ease and speed with which it may become absorbed into the circulation. In case of illness this is often a very important point. It is not a question so much of the utilization of a large amount of nutrients as the absorption and assimilation in small quantities which will sustain life until the disordered conditions disappear. For these reasons the meat extracts have a value. There is, however, little doubt of the fact that in the popular mind a great deal more credit is given to meat extracts than should properly belong to them. They must be regarded principally as condimental and incident to nutrition rather than as nutritive substances. The claims which are made by the manufacturers are sometimes misleading, as, for instance, that one pound of extract contains the nutritive properties of many pounds of meat. Such a statement, of course, is absurd upon its face and should not be allowed to go unchallenged. Even when meat extracts are reinforced by the addition of soluble or comminuted fiber, as is often the case, the quantity of nourishment is very small as compared with a similar weight of meat itself.
It is not intended by the above remarks to cast any discredit upon the value of beef extract, as its value has been attested in numerous cases. It is only designed to call attention to the fact that as food these extracts have comparatively little value. They may be useful as stimulants or as condimental substances or as a means of speedily introducing a soluble nutrient in the case of disease where it is extremely important that even small amounts of nutritious material should enter the body.
Beef Juice.
—A distinction is made between a beef extract and a beef juice. The latter term applies solely to the liquid naturally remaining in the fresh meat after its proper preparation for consumption, that is, after the withdrawal of the blood and the proper cooling and storing of the flesh. The fresh meat is then subjected to strong pressure and the juices which are extracted are concentrated in vacuo to the proper consistence. The meat of old bulls is often used. A true beef juice must be extracted from the cold meat and not with the aid of heat, hot water or other solvents. It is difficult to preserve an extract of this kind without sterilization, and the heat required for sterilization is likely to coagulate some of the albuminous material which is expressed. It is a great temptation, therefore, in some cases to preserve the beef juice by a chemical preservative other than common salt. Boric acid and sulfite of soda may be used for this purpose, but these substances are objectionable on the score of possible injury to health. Glycerine is also used. Inasmuch as these juices are usually given to invalids or those whose digestive functions are impaired it is most important that injurious substances should be omitted. In case of pressure it is advisable, in some cases, to chop the meat very fine, and in this comminuted condition extract the juice with cold water. This does not produce any change in the character of the juice and the water is subsequently removed by evaporation at a low temperature in vacuo. Beef juices are usually prepared from heated meats.
Composition of Beef Juice.
—The composition of beef juice from different parts of meat which was previously heated externally is shown in the following table.
COMPOSITION OF BEEF JUICE AND MEAT EXTRACT.
| Beef Juice. | Meat Extract. | |
|---|---|---|
| Water, | 90.65 | 21.66 |
| Ash, | 1.36 | 20.46 |
| NaCl (salt), | .15 | 5.47 |
| P2O5 (phosphoric acid), | .36 | 4.55 |
| Fat, | .19 | .50 |
| Acid (as lactic), | .15 | 8.42 |
| Nitrogen (total), | 1.15 | 7.66 |
| „insoluble and coagulable, | .68 | .48 |
| „as proteoses, | .04 | 2.02 |
| „as peptones, | .14 | 1.90 |
| „meat bases, | .30 | 3.05 |
| „creatin, | .75 | |
| „xanthin bases, | .04 | |
| „ammonia, | .21 |
The above analyses show the general character of meat juice extracted first by externally heating the meat and then pressing. They show that there is less nitrogenous bodies present in meat juice than there is in meat extracts. It is evident that meat extracts cannot be heated for sterilization without coagulation of the globulins. When it is advisable to use a beef juice in a case of illness it is far better to prepare it at the time when it is used than to prepare it on a commercial scale and preserve it by any of the chemical means in vogue. Meat juice can be very well prepared for domestic use by chopping the meat very fine, placing it in a vessel, heating to 140° F., and pressing it by any simple means, as, for instance, with the hand or by using an ordinary lemon squeezer. The juice obtained in this way can be flavored with salt and spices to suit the taste of the patient, and used immediately. In some cases, in order to get a greater yield, pure cold water may be mixed with the chopped meat and a somewhat dilute juice obtained but giving a greater yield of nutritive material for the same weight of meat.
Various names, fanciful and otherwise, are given to the so-called beef juices. These names are either fanciful or, as in the case of beef extracts, that of the manufacturer. Some of the fanciful names are, like those already mentioned, suggestive of origin. Some of these have large quantities of coagulable protein, like albumin, while others have such small quantities as to indicate that they are not wholly beef juice. In the case of some of these preparations there is some indication that they are prepared chiefly from blood and thus are not true meat juices. Naturally there must be particles of blood in a meat juice and the mere occurrence of blood cells would not be an indication that blood itself had been used in its preparation. By reason of these facts the use of so-called meat juices is restricted. They contain relatively very little nutritive material, they are sometimes preserved with harmful chemicals and they may be made from blood, and in general there is such a degree of secrecy attending their preparation as to warrant the physician and patient to confine themselves to the domestic article prepared at the time of using. Another objection which is not of a hygienic character is found in the great expense of securing a very little nourishment by this means. The quantity of juice which meat will yield is very small and, therefore, the relative expense for any given quantity of nourishment is far greater than it is even in the case of beef extract. While in the case of rich patients an objection like this is of little value, in the great majority of cases it should be given due consideration.
Soluble Meats.
—Various attempts have been made to put soluble meats upon the market for use, especially for invalids and in cases of disordered digestion. The principle which underlies the preparation of these meats is to subject them to a certain degree of artificial digestion, by means of which the protein matter becomes converted into soluble forms, either albumose, proteose or peptone. The process which is employed is a simple one, namely, the comminution of the meat into as fine particles as possible and its admixture with hydrochloric acid and pepsin. It is then subjected to artificial digestion until a considerable portion of the meat is soluble. Another method of preparation is to omit the pepsin and after the addition of hydrochloric acid to place the meat in a digestor where it is subjected to a temperature of steam under pressure for a considerable length of time. A goodly proportion of the meat becomes soluble under this process. After the preparation is completed the residual hydrochloric acid is neutralized by carbonate of soda, forming common salt, which gives the proper flavor to the compound.
The composition of soluble meat prepared in this way is given in the following table (Foods and Principles of Dietetics, by Robert Hutchinson):
| Water, | 67.21 | percent |
| Fat, | 5.93 | „ |
| Albumin, | 11.00 | „ |
| Peptone, | 6.51 | „ |
| Meat extract, | 7.55 | „ |
| Ash and salt, | 1.74 | „ |
A meat solution of this kind is not really a solution, since not only is that part which passes into solution contained in it, but also the residual meat fibers which are not dissolved but so softened by the process that they lose their distinct form and can be rubbed up to a thick pasty mass. The product, therefore, consists not only of the part of the meat rendered thoroughly soluble in water by the process, but also of a residual part, softened and reduced to a paste. The mass has practically the same nutritive value as an equivalent amount of meat with the claimed advantage that a large portion of it is already soluble. This partial predigestion may be of value in cases of disease or disordered digestion of any kind, but there is no reason for believing that the healthy stomach requires any sort of artificial predigestion for the proper conduct of its functions. On the other hand, there is every reason for supposing that any kind of predigestion which is at all effective will in the end prove injurious to healthy digestive organs by depriving them of a part of their normal functions and thus tending to bring them to a condition of feebleness which may result in the omission, in part, of the normal functions of the vital organs.
Preparations of Blood.
—There is no doubt of the valuable nutritive properties of blood and its preparations are sometimes used as foods. There is a deep-seated prejudice against the use of blood as human food, doubtless based on older and more effective grounds than even the laws of health promulgated by Moses. Man is an animal of some refinement of character and the sight or use of blood is repugnant to his finer instincts. Sometimes blood is dried and powdered and the blood powder mixed with other food. Another method is to coagulate the blood, then remove the coagulated portion and use the residue for food purposes. This preparation, of course, contains no coagulable portions of blood, that is, the protein thereof known as fibrin. There is no reason for believing that preparations of blood will ever occupy any prominent position in the food supply, either of persons in health or of invalids.
Beef Tea.
—A very common food preparation from beef is that known as beef tea. In all essential particulars beef tea is nothing more than a rich unfiltered soup stock. Inasmuch, however, as it is constantly prescribed in many kinds of illness and is prepared under certain conditions it should be mentioned specially here in addition to the preparations already described. As in the case of meat juice, beef tea should always be prepared in the home, and immediately before using. It is a preparation which can not be properly made and kept without the addition of some preservative which renders it totally unfit for human consumption. The very choicest portion of the beef should be selected in the preparation of beef tea and it should be reduced to a fine state of comminution. The removal of the fat and tendons should be as complete as possible, as particularly the latter tend to add to the extract more of the gelatine-like principles than is desirable. The fragments should be mixed with a sufficient quantity of cold water to make the desired amount of beef tea, usually one pound of water to a pound of comminuted beef is a good proportion. The mixture should be kept cold for a considerable length of time with frequent stirrings in order to extract as much as possible of the nitrogenous matter which becomes coagulated by heating. Salt may be used not only to promote the solubility but also to give the proper taste. After the lapse of an hour or more the vessel may be covered and gradually warmed. During this warming the mass should be frequently stirred so to as promote the solution. When finally the extraction is complete, before the tea is administered it should be cooked, that is, heated to the boiling-point, by which process the soluble protein is coagulated but not hardened, and the material is rendered more palatable. The beef tea should be administered without separating the coagulated fragments of albuminous material, which is in a state easily digestible, and adds much to the nutritive value of the mixture. Finally the residue of beef may be put into a bag and subjected to pressure to remove as much of the juice contained therein as possible. The difference between beef tea and soup stock, as will be seen, is largely in the filtering. The beef tea should retain the coagulated flocks, while in the soup stock they are removed. One pound of good lean beef and one pint of water yield about one-half pound of good beef tea. As in the case of soup stock, beef tea is not a very nutritive substance. It is, however, stimulating, and the nourishment which it contains is quickly absorbed. The soft, coagulated flocks of albumin are readily digested, and often a patient may be nourished for days on a preparation of this kind when he is in a condition which renders it impracticable to use either solid or other liquid foods.
Beef tea is also made on a large commercial scale and with some degree of approximation to the home prepared article. For various reasons, however, which have already been advanced, a well made domestic beef tea which can be used as soon as prepared is to be preferred in all cases to the manufactured article. A beef tea properly made contains approximately the following composition:
| Water, | 88.00 | percent |
| Meat bases, | 3.50 | „ |
| Protein—soluble and flocculated, | 8.00 | „ |
| Ash and salt, | 1.50 | „ |
Dried and Powdered Meats.
—The preparation of dried meat has already been described. There has lately been placed upon the market a number of preparations dried and finely ground, under various names, fanciful and those of the manufacturer. Inasmuch as ordinary meats are largely composed of water, it is evident that if the water can be removed without impairing the quality of the meat, great expense in transportation would be saved and the use of preservatives would be unnecessary. Various attempts, therefore, have been made to place dried meats upon the market. The meat powders are not only offered in their natural state of desiccation but also are prepared with a more or less previous digestion. One of the most common of these meat powders is known as somatose, which has been made in large quantities, and sold throughout all parts of the world. It consists largely of albumoses rather than of peptones, but this is true of a great many of the so-called peptone preparations. The composition of somatose is represented in the following table (Allen’s Commercial Organic Analyses, Vol. IV, page 384):
| Water, | 14.25 | percent |
| Albumin rendered soluble by alkali, | 21.83 | „ |
| Albumin, | 3.40 | „ |
| Albumoses, | 33.96 | „ |
| Peptone, | 3.06 | „ |
| Meat bases, | 2.62 | „ |
| Ash and salt, | 5.30 | „ |
The above data show that the meat still contains nearly 15 percent of moisture and that an alkali has been used to render the protein more soluble. This alkali has increased the quantity of mineral matter over that which would naturally be present. Whatever may be the relative value of the prepared protein matter as compared with that in the original meat, it is seen that a large quantity of it, practically as much as was in the original meat, has been preserved in the finished product. Whether or not it is advisable to use a preparation of this kind is a question to be left with the physician. It may be said unhesitatingly that in all cases of health somatose could not possibly present any advantage over fresh meat. On the contrary, for theoretical and practical reasons, it is certain that it is less valuable.
Composition of the Ash of Meat Juice and Meat Broth.
—The principal mineral component of the natural juice of meat broth or meat extract is phosphate of potassium, though there are also small quantities of magnesium and smaller quantities of calcium present. In addition to this there is a certain quantity of common salt present, which is determined, however, largely by the method of preparation. The following analysis shows the composition of the ash of a meat juice to which little or no common salt has been added:
| Potassium (K), | 34.40 | percent |
| Sodium (Na), | 9.70 | „ |
| Calcium (Ca), | .36 | „ |
| Magnesium (Mg), | 2.55 | „ |
| Phosphoric acid (P2O5), | 27.00 | „ |
Other constituents are not determined in this analysis. The phosphate of potassium may therefore be regarded as the principal natural ash constituent of meat extract and meat juice. (Zeitschrift für Biologie, Vol. XII, 1876.)
Adulteration of Meat Extract.
—The principal adulterations of meat extract have already been mentioned. The substances used in preserving it are of the greatest hygienic consequence. These are chiefly salt and glycerol or alcohol. The use of all of these substances is reprehensible. Fortunately they are seldom used. Another adulteration which has been practiced is mixing the meat extract with extracts of yeast. The extract of yeast has valuable dietetic properties and contains the active principles of fermentation. It also resembles, in many respects, physically and chemically, the extract of meat, and can, therefore, be mixed with meat extract, and, being a cheaper article, forms a mixture which can be sold at a greater profit. The presence of yeast extract in meat extract can easily be determined by treating the mixture with a strong solution of sulfate of zinc and filtering. In meat extract the filtrate obtained is always quite clear, but when a yeast extract is present the filtrate is turbid.
Active Principles Contained in Meat Extract.
—Attention has already been called to some of the more important active principles, namely, meat bases which form a valuable portion of meat extract. There are various forms of nitrogenous bodies, however, besides meat bases, which become soluble naturally in meat or by the treatment of meat with digestive ferments. Lean meat, as is well known, consists almost exclusively of protein matter and water. This protein matter is principally insoluble. Under the action of digestive ferments the protein of meat becomes broken up into more soluble bodies, known as albumoses, proteoses and peptones,—the latter being the final product of solution. These bodies are still true protein bodies containing the elements of sulfur as one of their essential constituents. The meat bases, on the contrary, contain the other elements that are in protein but do not have the sulfur element. They belong to that class of bodies which is known as simple amido compounds. All of these bodies are mixed together in meat juice or beef extract, and it is an important task of the chemist to separate them, both from an analytical point of view and the determination of their relative abundance. There is also another soluble or semisoluble protein substance in these extracts derived from the tendinous tissues and bones, namely, the gelatine or glue. This is quite a common product, being the soluble protein procured by the digestion of the tendons and bones. It is important, therefore, that the chemist should distinguish between the gelatine and the amido bodies. There is also a true and a false protein form of these soluble bodies, the true one being formed by natural proteolytic ferments and the false one being formed by heat or digestion under pressure of steam. The chemist should also be able to distinguish between the true extract formed directly from the meat and the yeast extract used as an adulteration.
It is not the purpose of this manual to enter into the details of how these different bodies may be distinguished from one another, as that is purely a chemical study. It is due, however, to the general reader that some explanation be given of the different classes of bodies which are contained in these extracts.
Relation between the Price of an Extract and its Nutritive Value.
—The studies made in the Bureau of Chemistry show that there is little relation between the price of a beef extract and its real nutritive value. In three cases of extract which are all well known brands and are of the thick or pasty variety, showing that a dissolved meat had been added to them, the average weight of a package costing 45 cents was only 55 grams, or nearly a cent a gram. In another three samples of extract, also well known brands, of the same pasty variety and costing little more per package, it was found that the weight of the more expensive variety was double that of the first, costing only one-half cent per gram. In the case of the liquid extracts where no pasty material is incorporated there is still greater variation in the relation of the price to the nutritive constituents. An extract which retails for one dollar per bottle contains 91.69 percent of water and only .42 percent of nitrogen. Another so-called meat extract which retails at 60 cents per bottle must have been wholly an artificial product, since it contained no creatin or creatinin at all. It was also preserved by the addition of alcohol and contained an artificial coloring matter.
The ash existing in these extracts is, of course, usually due to the presence of large quantities of common salt. Sodium chlorid is added to this extract without any definite rule at all and sometimes in very excessive quantities. In some cases thirty percent of the total extract is composed of common salt. In other words, a person taking a solution of this kind would be injecting into his stomach a very concentrated brine. When common salt may be sold at the rate of one dollar per pound, the profit on the transaction is one which ought to make the business exceedingly attractive.
The total phosphoric acid in the ash also shows variations, and if it were not so easy to add artificial phosphoric acid the actual amount present might be taken as a base by which quality could be judged. In the natural extract the total phosphoric acid should be in the proportion to organic phosphoric acid as 10 to 1, which is the natural condition in which it is found in meat extract. In many cases the amount of inorganic phosphorus is so great as to render it certain that a phosphate, probably the phosphate of soda, has been added. In another case the quantity of organic phosphoric acid was very much greater than could have possibly been the case in a natural product, indicating the addition of lecithin or glycerophosphoric acid. The amount of fat in beef extract, when properly prepared, should be very small and should certainly not exceed one percent, since by the proper method of preparation the fat is largely separated. In the pasty material, however, where the meat is reduced to a pulp and retained in the package the amount of fat will be very much greater.
The Nitrogenous Bases.
—The average nitrogen content of the pasty or solid extracts varies from 6 to 9 percent. The nitrogen in the meat juice is subject to much greater fluctuation, depending largely on the content of solids. Although a high nitrogen content is not a guarantee of the character or mode of manufacture of an extract, it is naturally expected and is desirable.
The addition of gelatine to extracts is now largely practiced and has been for some years. By adding gelatine the manufacturer raises or maintains a certain nitrogen content, but supplies the nitrogen in a form lacking in all quickly stimulating qualities, and the natural flavor of the meat extract nitrogen is lowered. The buyer is consequently deprived of the characteristic essentials of a beef extract although the nitrogen content is relatively high. In many cases only a small proportion of the original gelatine exists in the extract as such. The gelatine is converted by a gradual process of hydration into gelatoses and gelatine peptones. While the separation of gelatine from protein matter is a process in anything but a satisfactory condition, it is a far simpler process than the detection and separation of gelatoses and gelatine peptones from albuminoses and peptones. The question has not been thoroughly studied up to date.
The question of adulteration of meat extracts with gelatine is not the only form of adulteration we have to face. The mixing of varying amounts of yeast extract with meat extracts is being practiced at the present time in some countries. As we have not investigated this question, we cannot state whether it is practiced in this country at the present time or not.
Kinds of Preparations.
—Meat preparations of the above types in general may be divided into three classes, liquid extracts, pasty extracts and powdered extracts. In addition to the above, within the last few years beef extract pellets, some of them being enclosed in gelatine capsules, have appeared upon the market. The old-time product of Liebig’s extract belongs to the second class, in which we also find many of our best known brands. The liquid extracts are varied and numerous and their number is rapidly increasing. The amount of meat extractives in some of these liquid products is remarkably small, the quantity of solids in two or three cases being under 10 percent. Alcohol is sometimes met with in these liquid preparations. The meat powders are far less numerous than the extracts of the first two classes. They consist largely, if not entirely, of albuminoses and peptones in addition to some insoluble proteid matter.
Moreover, it is necessary to distinguish between a meat extract containing large amounts of stimulating amido-acids and relatively small percentages of albuminoses, peptones and insoluble proteid matter on the one hand, and, on the other hand, an extract, or, more properly, a meat product, which consists largely of albuminoses, peptones and insoluble matter and relatively small amounts of amido-acids. The food value of this last group of products is undoubtedly greater than that of the former group, but being sold as meat extracts, their value should be based on the amount of extractives they contain and not on their food value.
The value of the amido-bodies, such as the meat bases, as food, is of uncertain character, but we must admit, as in the case of alcohol, they can at least be burned and furnish energy to the body. Like alcohol, the value of meat extractives lies principally in their stimulating qualities. The active principles of tea and coffee are on a similar basis. As these simpler amido-bodies are the final links in the long chain of hydrolytic products of the proteid molecule prior to the complete resolution of that molecule into carbon dioxid, water, etc., it is readily seen that an ounce of meat extractives (the various amido-bodies) represents a far larger amount of beef than an ounce of albuminoses does. The various protein bodies and amido-acids are closely interwoven and it is impossible to produce amido-acids without producing albuminoses and peptones. Consequently, every commercial meat extract must consist partly of albuminoses, peptones, etc. The best of our extracts on the market to-day contain about 50 percent of their total nitrogen in the form of meat base nitrogen. When an extract contains less than 5 percent of its nitrogen in the form of meat base nitrogen the term “extract” seems to be no longer applicable. It is evident that the product represents much less meat than an extract with 50 percent of its nitrogen in the form of meat base nitrogen, provided the total nitrogen in both cases is approximately equal.
The proteid matter coagulated by heating to boiling, as well as the proteid matter insoluble in cold water, are both undesirable factors in an extract of meat. As a rule, the lower the proportion of these constituents, the higher the character of the meat extract. The same thing holds true in regard to the presence of albuminoses and peptones.
The quantity of total nitrogen in the form of meat base nitrogen in the best extracts reaches 50 percent. In one of the poorest it is 3.82 percent. The food value of the latter product might be greater than that of the former, but its cost of manufacture and its stimulating value are much less.
Creatin figures are very interesting and of much value in determining the source and value of an extract. Creatin is the principal amido-body found in meat, consequently we expect to find it or creatinin, its hydrated form, in still larger quantities in meat extracts. In several cases which came under our notice where the extract acted suspiciously, the creatin values were nil, and in such cases grave doubts exist as to the source of the extract. Our best extracts give high creatin as well as high meat base figures.
The xanthin bases and ammonia nitrogen figures present a variety of problems. While the xanthin bases are desirable constituents, ammonia in any amount is not. It is questionable whether the ammonia figures obtained by the magnesium oxid method do not give too high results (W. D. Bigelow).
Gelatine.
—Gelatine is a substance obtained from the nitrogenous portions of bones, hide, horns, hoofs, connective tissue, tendons and other nitrogenous matter of the animal. One of the principal constituents of these bodies is a substance known as collagen. When this is heated either under pressure or without pressure it is changed to gelatine. Glue is unrefined gelatine or impure gelatine to which usually some substance has been added to increase its holding power. A type of gelatine known as isinglass is made from the bladders of sturgeons.
The general process of manufacturing gelatine is as follows (Whipple, Technology Quarterly, Vol. XV, No. 2, June, 1902):
“The hide scraps are first macerated and subjected to the action of a solution of lime or caustic soda in pits for two or three weeks. This dissolves most of the blood and saponifies the fats. The excess of lime or soda is then largely removed by washing and the solution steamed to dissolve the gelatine, but an excess of heat is avoided. Sulfurous acid is used to bleach the gelatine. When of sufficient strength, the gelatine is allowed to harden in molds or on slabs, and is ultimately dried in sheets on wire nets. Bone gelatine is made in a somewhat similar manner. The bones are crushed, boiled, treated with hydrochloric acid, and the gelatine is dissolved as before, washed, bleached and dried in sheets. The process requires a number of weeks.”
Gelatine is also made from bones, fresh as well as old, and from the residues of bones used in the manufacture of buttons. The thin slices of the bones are treated with acid until all the phosphate of lime is extracted. They are then treated with lime and the gelatinous residue is then dissolved in warm water and purified for use.
The use of gelatine as a food has of late years become very common. The ease with which it can be made into jellies, the consistence which it gives to ice-cream and its general utility in the cuisine have made it deservedly popular. Gelatine is the product of some of the nitrogenous parts of the animal and should be made only from the edible parts thereof. It is particularly abundant in the tendinous portions of the animal and in the tissues about the head, from which a large part of edible gelatine is made. No portion of the animal which is filthy or unfit for food should ever enter into the composition of the gelatine. If the parts from which the gelatine are made are cured previous to manufacture they should be cured in a perfectly sanitary way, as carefully as any other part of the meat. There can be no objection to the use of gelatine made from these sanitary materials in foods of all kinds.
There is, however, a possibility that some of the gelatines on the market may be made from materials wholly unfit for food. The food law forbids the use of animal substances unfit for food either directly or indirectly. As an illustration of this condition of affairs I may call attention to the fact that a part of the gelatines sold in the United States are made from parts of animals slaughtered in South America. It is not known to the consumer in what conditions these parts are preserved and transported. They may be possibly packed with the hide and sent to Belgium or other countries in a filthy, putrid and abhorrent state and these parts be cut from the hides before they are sent to the tanneries and converted into gelatine and sold as edible gelatine. Such a possibility should not exist, and there is no danger of its existence with high class manufacturers. A part of the horns is also used for such purposes, which being of an inedible portion and unfit for food is not admissible, under the law, as a constituent of edible gelatine. All such materials should be excluded in the manufacture of such an important product. Further than this, it may be stated that the line of demarcation between gelatine and glue is not always as well drawn as it should be, and this is illustrated in the report that the gelatine and glue are manufactured in the same factory, and the same conditions of odor and insanitation which adhere to glue may attach themselves to the gelatine. Such a condition, of course, would be an exceptional case, but its possibility should be excluded. Under the food law only those forms of gelatine first described above can be legally made and sold for use in food.
Adulteration of Gelatine.
—The adulterations of gelatine are such as those referred to above in the form of raw materials employed which are insanitary and unfit for food. In addition to this, bleaching agents, namely, sulfurous acid or sulfites and mineral acids, are often employed in the manufacture, portions of which may remain in the finished article. All of these substances must be regarded as adulterants and as insanitary and unsuitable to gelatine, and to that extent unfit for human consumption.
Presence of Tetanus in Commercial Gelatine.
—The Public Health and Marine Hospital Service has investigated gelatine to determine whether or not it may be infected with pathogenic germs. The conclusions of the investigation are as follows (Bulletin No. 9, Hygienic Laboratory):
“Seven samples of gelatine examined; one showed tetanus spores.
“Two samples showed an oval end-spore rod, whose identity was not proved, but, in stained specimens, it would be hard to distinguish from tetanus, if indeed not tetanus with diminished virulence.
“In tetanus investigations it is important to use freshly made bouillon, as the organism is apt not to germinate in bouillon over ten days old. The thermal death point of the organism isolated was found to be between twenty and thirty seconds at 100 degrees C.
“It is important, therefore, that gelatine to be used for injections should be boiled at least ten minutes on account of the variability of the thermal death point in different species of tetanus. Whether this amount of heating impairs in any way the hemostatic power of gelatine has not been settled, but in case it does it is believed that the danger from tetanus more than overbalances its therapeutic value.
“It is suggested that when, as in hospitals, there is likelihood of gelatine injections being used for hemostatic purposes the gelatine solution be sterilized by the fractional method on three successive days and kept ready for use in sterile containers.”
From the data given above it is seen that gelatine may become infected and the material from which it is made for edible purposes should be healthful, sanitary and fit for food. It is not likely that tetanus germs would prove dangerous when taken into the stomach, but freedom from infection should be secured if possible. These investigations show the wisdom of the pure food law in forbidding the use of parts of animals unfit for food, whether manufactured or not, in the production of food products. It is evident that a sufficient quantity of fresh, sanitary material or material properly preserved can be obtained in this country or in other countries to supply the needs for edible gelatine without resorting to the use of inedible parts of hides, horns, hoofs and other waste and unfit portions of the animal.
Summary.
—Above have been presented some of the principal meat foods, the analytical data which show their composition, the processes by means of which they are prepared and the principal methods, objectionable and otherwise, by which they are preserved.
Meat is a staple article of diet among almost all nations of men. The anatomical structure of the human animal indicates that his environment has adapted him to eating meats of all kinds. In other words, man is an omnivorous animal. He has been developed in an environment in which all kinds of meats and vegetables have ministered to his sustenance, and thus he is an omnivorous animal both by evolution and necessarily by heredity. That man can live and flourish without meat has been fully established by experiments, but that man cannot be nourished by meat alone has likewise been fully established, so that if the human race were necessarily to be deprived either of animal or vegetable foods, it would be the animal food which must be sacrificed.
It is not the purpose of this manual to discuss the relative merits of vegetarianism as compared with the common diet of the human race. It may not be amiss, however, to say that probably in the United States especially, a larger quantity of meat is eaten than is either necessary or wholesome. The people of our country are better able to supply themselves with expensive foods than those of other countries, and of the common foods meats are far more expensive than cereals. The eating of larger quantities of cereals and smaller quantities of meat would probably be conducive both to economy and health. It appears to be certain that the meat eating of the future may not be regarded so much as a necessity as it has in the past, but that meats will be used more as condimental substances than as staple foods. In all meat, for instance, that costs 25 cents a pound, such as steaks, there is over one-third or a half of it which is inedible, so that the edible portion really costs double that amount. On the contrary, when a pound of flour or maize is purchased, the price of which is perhaps only one-eighth that of meat, the whole of it is edible. Thus, from the mere point of economy as well as of nutrition the superiority of cereals and other vegetable products is at once evident. On the one hand, a cereal is almost a complete food containing all the elements necessary to nutrition, and it costs only a few cents a pound. On the other hand, a steak or roast is only a partial food and it costs much more than cereals.
It is hoped that one purpose of this manual may be secured, namely, by showing the consumer the actual composition of the different kinds of food and their method of preparation he may be led in the selection of his food to follow the dictates of science and economy to a certain extent rather than merely the impulse of taste. The eating of such large quantities of meat is merely a habit which often is developed in children through the carelessness and ignorance of parents, much to the detriment of the child as well as to his future health and activity. It is believed that if the true principles of the use of meat were properly inculcated a large saving in the energy of the wage earner as well as those in more affluent circumstances would be secured.
Sound principles of economy establish a better condition of health and lead to greater activity and fruitful labor.
Terrestrial Animal Oils.
Terrestrial animal oils are obtained directly from parts of the animals which yield, at ordinary temperature, a substance which remains liquid. The fats which are in the feet of the animals are usually more liquid than in any other part of the body, and hence the natural animal oils are derived largely from the feet. Among the most important are sheep’s foot oil, horse foot oil, and neat’s foot oil, which is obtained from the feet of cattle. These oils are all highly valued for technical purposes, especially for lubricating, and for this purpose bring a very high price. They are not used or should not be used for edible purposes, though they perhaps may sometimes be used in cooking. Neat’s foot oil, especially, on account of its high price, is often subjected to adulteration, and is mixed for this purpose with cheap vegetable oils, such as cottonseed. Fish oil is also often used in the adulteration of neat’s foot oil, though the addition of any of these oils to neat’s foot oil raises the iodin number to a very high degree, and hence this addition is easily detected by the chemist.
Lard Oil.
—Lard oil is one of the most important of terrestrial animal oils. It is made from lard by melting it and allowing it to slowly cool. The stearin in the product crystallizes first, and when it reaches a condition favoring the separation of the stearin the mass is subjected to straining or pressure, whereby the olein or liquid portion of the oil is separated, and thus, having been freed from the most of its stearin, remains liquid at ordinary temperature. The residue is known as lard stearin and is largely employed in the preparation of lard to give it a higher melting point and in the manufacture of oleomargarine.
Lard oil is used to some extent for edible purposes and is itself sometimes employed in the manufacture of oleomargarine when mixed with tallow or tallow stearin.
Properties of Lard Oil.
—It is evident that the chemical and physical properties of lard oil are determined by the completeness with which the stearin is separated. Inasmuch, however, as the conditions of manufacture are nearly constant, lard oil has characteristics of a physical and chemical nature which do not vary greatly. The specific gravity of lard oil at 15 degrees is about .916, and its iodin number varies from 68 to 75. When made of the best material it has a neutral taste, not an unpleasant odor, and, therefore, can be used for edible purposes without introducing any characteristic odor or flavor into the prepared food. In point of fact, however, it is not used to any extent for edible purposes except in the manufactured articles above mentioned. When carefully made and of the proper quality pure lard oil should be practically free from free acid.
Adulterations.
—On account of the high value of lard oil for lubricating and other purposes it has been subjected to extensive adulterations. The addition of cheaper animal oils or vegetable oils has been largely practiced. Fish oil, blubber oil, and other marine animal oils have also been freely used in the adulteration of lard oil whenever the difference in price has rendered it advisable. These adulterations are of such a character that they can be detected only by the skilled microscopist and chemist. The other animal oils, both of marine and terrestrial origin, while important from a technical point of view, are of no significance in respect of edible qualities.
PART II.
POULTRY AND GAME BIRDS.
Application of Name.
—The term poultry for descriptive purposes may be applied to those classes of feathered domesticated birds used for human food. It, therefore, includes practically all of the domesticated fowls. The term game bird, for the purpose of this manual, is applied to feathered animals which are wild and which are used for human food. This also may apply to almost all wild birds, since at times they practically all have been used for food purposes. Here only those in common use, both domesticated and wild, will be referred to. In connection with poultry the eggs of the birds will be considered.