File:Preventive medicine and hygiene (1917) (14598418900).jpg

Identifier: preventivemedici1917rose (find matches)
Title: Preventive medicine and hygiene
Year: 1917 (1910s)
Authors: Rosenau, M. J. (Milton Joseph), 1869-1946 Whipple, George Chandler, 1866-1924 Trask, John W. (John William), b. 1877 Salmon, Thomas William
Subjects: Hygiene Public Health Sanitation Military Hygiene
Publisher: New York, London, D. Appleton
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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mall quantities, are lecithin, cholesterin, citric acid,lactosin, orotic acid, and ammonia. The composition of cows milk may be understood from the schemesprepared by Lucius L. Van Slyke and S. M. Babcock, given on page 555. Proteins.—The three proteins constantly foimd in milk are casein,lactalbumin, and lactoglobulin. A trace of fibrin, mucin, and other pro-teins sometimes occurs. The proteins, in milk of a given species are quite constant both incomposition and amount; it is, therefore, not necessary, as a rule, tomake a special analysis for them. They may be estimated by subtract-ing the fat, sugar, and ash from the total solids. Casein is a highly specialized protein found in the secretion of themilk glands of all mammals, but nowhere else in nature; it is a nucleo-albumin, and as such contains phosphorus. It is insoluble in water, butby virtue of its property as an acid it forms soluble salts with alkalis. *When not otherwise specified in this section milk refers to cows milk.
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iQ00t^^l>00t^ t^ r)H ^ O iM t^ O dodddodo OfL,ffi§meqOOOO<lh:iO - 3 S 555 556 ANIMAL FOODS: MILK There are two series of casein salts, basic and neutral; solutions of thelatter have a milky appearance. In milk, casein is found dissolved inthe form of a neutral calcium salt, which accounts in part for the whiteopalescent appearance of milk. Casein exists in milk in the form ofcaseinogen, that is, casein in combination with calcium phosphate. Thecaseinogen is held in solution by the calcium phosphate. It is not coagu-lated by heat, but is precipitated by acids, for the reason that acidstake the calcium from the calcium phosphate, and thus throw the caseinout of solution as a curd. This flaky or lumpy precipitate is againsoluble in lime water and dilute alkalis. Casein is also thrown out ofsolution by rennin. Lactalhumin is very similar to the serum albumin of the blood, butit appears to differ from this in some particulars. It coagulates byheating to 70° C, but not with dilute a

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