xanthine are very similar in their reactions and the latter might easily be mistaken for the former although there could be no question of identity if nitrogen were determined, as carnine contains 28.57% and hypoxanthine 41.18%. In yeast extracts Micko found adenine as the chief purine base; guanine, hypoxanthine, and xanthine were also present, the quantities being in the order named, while carnine was not found. Products of Hydrolysis. By hydrolyzing meat extracts, according to Fischer's method, Micko* obtained glutaminic acid, alanine, leucine, isoleucine, aspartic acid, and glycocol. In addition other amino acids were obtained but in too small quantities for identification. Hydrolysis of the precipitate obtained by salting out with ammonium sulphate showed that it consisted almost entirely of true proteoses and did not contain gelatin. The filtrate from the proteoses yielded on hydrolysis amino acids of which glutaminic acid and glycocol were the most abundant while alanine, leucine, and aspartic acid occurred in smaller amounts. Proline and phenyl-alanine were not found. Taurine not previously reported was isolated and identified. Chlorine in meat extract is usually calculated in terms of sodium chloride, which Richardson † points out is not scientifically accurate, since the chlorine derived from the meat exists chiefly if not wholly as potassium chloride. He considers that after allowing 0.06% of sodium chloride for every unit per cent of dry solid matter present any excess may be fairly considered as added salt. Analyses of both solid and liquid meat extracts by Micko,‡ Bigelow and Cook, Street,|| and Wright,¶ appear on pages 246 to 249. In a number of instances the results have been recalculated or rearranged to facilitate comparison. Meat Juices. A true meat juice, as prepared by expressing the liquid portion of meat, is a food product of high nutritive value and differs markedly in this respect from liquid extract and similar preparations on the market, some of which have been sold with misleading claims. While it is impracticable to concentrate a meat juice without precipitation or *Zeits. Unters. Nahr. Genussm., 5, 1902, p. 193. † Allen's Commercial Organic Analysis, Phila., 1914, 8, p. 394. Zeits. Unters. Nahr. Genussm., 5, 1902, p. 193; 20, 1910, p. 537; 26, 1913, p. 321. § U. S. Dept. of Agric., Bur. of Chem., Bul. 114. || Conn. Agric. Exp. Sta., Rep. 1907-8, p. 606. ¶Jour. Soc. Chem. Ind., 31, 1912, p. 176. alteration, the name meat juice is perhaps warranted in the case of some of the preparations now on the market, which unlike liquid extracts give strong tests for hemoglobin and contain considerable amounts of coagulable nitrogen. In view, however, of the difficulties of accurate classification, juices and fluid extracts are included under the same head in the tables on pages 246 to 248. Peptones and Meat Seasonings.-Certain meat preparations, known in Germany as "Speisewürzen," are made by digesting in various ways meat, or meat residues after extracting the soluble constituents, so as to obtain the constituents in a "predigested" condition and develop agreeable flavors. These preparations are generally known as "peptones in English, although this term is in many, if not all, cases inappropriate in view of their composition. Etienne and Delhaye obtained an English patent in 1890 for preparing a "peptone" from meat by heating the pulp in an autoclave from 150 to 175° C., separating the liquid from the insoluble matter, and digesting the latter with hydrochloric acid until the fibers are destroyed. The liquid obtained by the acid treatment, after neutralizing with sodium carbonate, is added to the concentrated aqueous extract. Micko,* in following this process, obtained by the acid treatment of the extracted meat a product with little odor but a decided meaty flavor which appeared to be due to amino acids. He obtained similarly flavored products by the hydrolysis of casein and silk fibroin. Examination of commercial preparations, made by the hydrolysis of protein matter, showed that they contained no coagulable or insoluble proteins, little if any proteoses or peptones, but often considerable amounts of ammonia. The amount of phosphoric acid present depended on the protein material employed but compared with that present in true meat extract was usually greater. Peptones are commonly used in soup preparations, often in conjunction with true meat extract, and various vegetable extracts for flavors. Soy sauce, the characteristic seasoning of chop suey, although a vegetable product rich in carbohydrates, resembles in its other constituents seasonings prepared from meat. Like the peptones, it contains only a trace of purine bases and little or no total creatinine. Suzuki, Aso, and Mitarai † separated from two liters of this sauce the following constituents in the quantities (grams) named: alanine 6.6, leucine 6, proline 3, lysine 2.6, *Zeits. Unters. Nahr. Genussm., 26, 1913, p. 322. † Bul. Col. Agr. Tokyo. Imp. Univ., 7, 1907, p. 477. COMPOSITION OF MEAT EXTRACTS AND SIMILAR PRODUCTS (MICKO). Glycogen present. meat fibers, pepper, capsicum. + Sucrose 38.91; invert sugar 5.38. Microscopic examination: tomatoes, capsicum, pepper. Microscopic examination: wheat flour, onion, paprika. § Microscopic examination: Made in the laboratory. Brand. COMPOSITION OF MEAT EXTRACTS AND SIMILAR PRODUCTS (STREET). MINERAL ACIDITY CC. FORMS OF NITROGEN. Water. Creatinine. Purine Base. Other Meat Ammonia. Petroleum Ether Extract. 19.92 29.26 17.42 1.74 6.75 11.0 5.5 1.78 0.10 0.01 0.38 $0.64 0.92 0.13 0.16 0.14 0.49 0.11 0.02 2.57 0.06 0.14 2.39 2.26 0.07 0.00 0.00 0.03 0.04 0.04 0.09 0.4 0.3 68.21 1.61 1.22 tr. 0.18 Biuret reaction for peptones in zinc sulphate filtrate. |