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.