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sodium hydroxide solution to alkaline reaction, and evaporate on the water-bath until all the alcohol is removed. Make up to 50 cc., add 5 grams of sodium chloride, acidify with sulphuric acid, heat to boiling, cool, and filter. Shake the filtrate with ether in a separatory funnel, wash the ethereal solution with a little water, and evaporate to dryness at a gentle heat. Test the residue as described in Chapter XVIII for both benzoic and salicylic acids.

Determination of Benzoic Acid.-Prepare the solution as described in the foregoing method, except that the meat is extracted with several portions of 50% alcohol, dealcoholize in an alkaline solution and proceed according to the La Wall and Bradshaw method, page 893.

Krüger Method.*-Place 50 grams of the ground sample, containing 70 to 75% of water, in a Kjeldahl flask with 45 cc. of 70% sulphuric acid. If less than 70% or more than 75% of water is present in the sample use less or more of the material and adjust the strength and amount of acid accordingly. Connect with a steam-distillation apparatus and heat cautiously with shaking, using an asbestos pad with a round hole cut in the middle to confine the heat to the portion of the flask in contact with the liquid. When the solution becomes clear distil in a current of steam regulating the heating of the flask so that the volume remains constant and a distillate of 500 cc. is obtained in about 75 minutes.

Filter the distillate, which must be cool as it flows from the condenser, wash with a little cold water, add sodium hydroxide solution to faint alkaline reaction, evaporate to small volume and transfer to a porcelain dish of 100-cc. capacity. Heat on a boiling water-bath and add in small portions with stirring sufficient cold saturated potassium permanganate solution to form a red color that persists for five minutes. Destroy the excess of permanganate with cold saturated sodium sulphite solution and evaporate to about Io cc. Transfer to a separatory funnel, acidify with 1: 3 sulphuric acid, dissolve the precipitate remaining in the dish with small portions of the sodium sulphite solution and dilute acid using the mixture to rinse the dish. Extract the solution, which should not exceed 20 cc. in bulk three times, with an equal volume of a mixture of ether and petroleum ether. Wash the combined extract three times with 3 cc. portions of water, and remove the last traces of water by shaking with the quantity of powdered gum tragacanth that is held on the end of a small knife blade. Transfer to a weighed glass dish, using a mixture of ether and petroleum-ether for rinsing, allow

Zeits. Unters. Nahr. Genussm., 26, 1913, p. 12.

to evaporate at room temperature, dry 2 hours over soda lime and weigh. As a check dissolve in neutral alcohol and titrate with N/10 sodium hydroxide using phenolphthalein as indicator. If the weight of benzoic acid is less than 30 mg. the results may be high in which case the benzoic acid is removed by sublimation and the dish reweighed.

Detection of Salicylic Acid.-Test a portion of the ether extract, obtained as described for benzoic acid, with ferric chloride solution. A deepviolet coloration indicates salicylic acid.

Detection of Starch in Sausages, Meat-balls, etc.-The addition of cracker or bread crumbs is best indicated by the presence of considerable starch, which is readily recognized by the iodine test, applied by boiling up a portion of the sample with water, cooling and adding a drop of iodine reagent to the liquid. The characteristic blue color is produced, if starch be present in notable quantity. Traces of starch may be due to the pepper and spices used in seasoning the sausage. A small admixture of starch is rendered apparent if a small portion of the sausage is treated with a drop of iodine reagent and viewed under the microscope. A microscopical examination will sometimes reveal the character of the starch, whether it is from cereals or from pepper, but in some preparations the starch is thoroughly cooked and its structure destroyed.

Detection of Coloring Matter.-Red Ocher is indicated by an excessive amount of iron in the ash.

Cochineal is most readily tested for by the method of Klinger and Bujard. The sausage, finely divided, is heated with two volumes of a mixture of equal parts of glycerin and water for several hours on the water-bath, the mixture being slightly acidified. The yellow solution is passed through a wet filter, and the coloring matter, if present, is precipitated as a lake by adding alum and ammonia, the precipitate is filtered off and washed, after which it is dissolved in a small amount of tartaric acid, and the concentrated solution, contained in a test-tube, is examined through the spectroscope for the characteristic absorption-bands of carmine lake, lying between b and D.

Spaeth has shown that both carmine (cochineal) and anilin red, which are the dyes most commonly used for coloring sausages, can be most readily extracted therefrom by warming the finely divided material a short time on the water-bath with a 5% solution of sodium salicylate.

*Zeits. angew. Chem., 1891, p. 515.
† Pharm. Central., 38, 1897, p. 884.

Vegetable and Coal-tar Colors.-In addition to the solvents named above various others, such as methylated spirits (Allen), acidified alcohol (A. S. Mitchell), amyl alcohol, ether, ammonia, and those used in the examination of fats and oils (Chapter XIII), are useful in special cases. The solvent, after filtering, is evaporated to small volume, acidified with hydrochloric acid, and white wool is boiled in it. If the wool is distinctly dyed, a coal-tar color is undoubtedly present, and this can often be identified by methods given in Chapter XVII. According to Marpmann, pure normal flesh containing natural color only is completely decolorized by macerating for two hours in 50% alcohol, while artificially colored meat remains colored after this treatment. Richardson* warns against mistaking for an artificial color the bright red substance often extracted by ether or alcohol and ether from meats cured with saltpeter.

Marpmann's Microscopical Methods.†-Moisten a thin section of the sausage with 50% alcohol, and examine under the microscope. Some colors are readily apparent without further treatment. If only traces of color are present, clarify the substance by treatment with xylol, which is removed by the use of carbon tetrachloride. The mass rendered transparent by this treatment is then immersed in cedar oil and examined, the coloring matters, if present, being especially apparent. If the color used is fuchsin (magenta), carmine, logwood, or orchil, the substance of the cell will appear stained. If acid coal-tar dyes are used, the liquid contents of the cell will show the color.

detects frozen meat by the

Detection of Frozen Meat.-Maljean aid of a microscope. A drop of the blood or meat juice is pressed out upon a slide and immediately examined before it solidifies. Fresh meat juice contains many red blood corpuscles, floating in a clear colorless serum, and readily apparent. In blood from frozen meat, the red corpuscles are nearly always completely dissolved in the serum, due to freezing, or, if not dissolved, are much distorted and entirely decolorized, the liquid portion being darker than usual.

Megascopically, the fresh meat juice is more abundant than that of frozen meat, and its color is deeper. According to C. A. Mitchell, if a small piece of meat once frozen be shaken in a test-tube with water, color is imparted to the water much more quickly than with fresh meat, and the color is deeper.

* Allen's Commercial Organic Analysis, Phila., 1914, 8, p. 364.

† Zeits. angew. Mikros, 1895, p. 2.

Jour. pharm. chim., 25, 1892, p. 348.

MEAT EXTRACTS AND SIMILAR PRODUCTS.

Meat Extracts. Methods of Manufacture.-Numerous preparations sold under the name of meat extracts have been on the market for many years. At the beginning of the nineteenth century the value of such extracts was known, but Liebig was the first some fifty years later to produce a commercial extract of meat. Liebig's preparation, as originally made, consisted of a cold-water extract of chopped lean meat, strained free from fiber, heated, filtered, and evaporated, thus containing little if any gelatin or proteins. Later, however, Liebig advocated the use of warm and even boiling water for extraction, by which method of preparation a greater amount of gelatin is brought into solution. He, however, condemned the use of salt.

The best modern meat extracts are prepared from meat freed from bone and superfluous fat by treatment with hot or boiling water, the time and temperature of extraction varying greatly with the different processes. While in Argentina, in former times when cattle were plentiful, meat extract was the main product and the extracted residue was considered of little value, at the present time, at least in the United States, the extract is commonly a by-product obtained by evaporating the liquor in which meat has been cooked for canning. The concentration of the liquor is carried on in vacuum kettles to a water content of about 50% for liquid extracts or 18 to 25% for solid or pasty extracts. As corned beef is the most popular canned meat, the liquor in which it is cooked is the chief source of supply. It contains a considerable amount of salt as well as a little saltpeter and sugar, the salt according to Richardson* being removed in sufficient amount by concentrating and centrifuging to comply with the standards as given on page 252. While in certain cases salt is a willful addition, under conditions now existing in the United States, it is more apt to be an impurity which the manufacturer is concerned in removing.

Meat extracts are commonly packed in glass or earthern-ware jars. The use of tin containers has been found objectionable because of the blackening of the cans due, according to Beveridge,† to tin sulphide, iron sulphide, and iron oleate.

* Allen's Commercial Organic Analysis, Phila., 1914, 8, p. 396.

†Third Rep. Com. Physiol. Effects of Food, Training and Clothing on the Soldier, London, 1908, 73.

Constituents.-The chief constituents are coagulable proteins belonging to the globulin and albumin groups, proteoses (albumoses), meat bases, phosphates, and chlorides. Small amounts of lactic acid, inosite, and other minor constituents of meat soluble in hot water are also present. True peptones are usually either not present or else the test is obscured by interfering substances. According to Micko * although gelatin in small amounts is present in the liquor from which meat extract is prepared, the finished product does not contain gelatin as such, but rather in the form of acid-glutin or gelatose which respond to the biuret test like gelatin, but do not form a jelly. This change is due to the action of lactic acid during concentration. Adam † reports formic acid in all the samples of extracts and related products examined. He states it is formed by the action of nitric acid on starch used in the process of

manufacture.

By far the most important constituents from the physiological standpoint are the meat bases to which the preparations owe their well-known stimulating properties. Indeed, a properly prepared extract has very little actual food value, but is rather to be regarded as a stimulant and condiment serving both purposes in an analogous manner to tea and coffee.

Creatine and Creatinine, aside from their value as stimulants, are of importance, as was first pointed out by Micko, in distinguishing true meat extracts from yeast extracts, which formerly, if not at the present time, were used as substitutes. These are usually determined together and the results expressed in terms of creatinine ("total creatinine ") after dehydrolyzing the creatine with acid.

Carnosine, Carnitine, and Methyl Guanidine, according to Krimberg, occur in meat extracts as well as in the living muscle.

The Purine Bases of meat extracts have been exhaustively studied by Micko.‡ who found hypoxanthine in the largest amount while xanthine and adenine were present in smaller amounts. He was unable to find either guanine, which according to Kossel is present in meat, or carnine which Weidel § reported in American meat extract. The former Micko

considers to have been eliminated in the manufacture

of the extract while

the latter he believes not to be present in either. Carnine and hypo

* Zeits. Unters. Nahr. Genussm., 14, 1907, p. 284.

† Arch. Chem. Mikros., 9, 1916, p. 77.

Zeits. Unters. Nahr. Genussm., 6, 1903, p. 781; 8, 1904, p. 225.

§ Ann. Chem. Pharm., 158, p. 353.

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