344 MILK AND DAIRY PRODUCTS 



Butyric, C 3 H 7 COOH 

 Caproic, C 5 HnCOOH 

 Caprylic, C 7 H 15 COOH 

 Capric, C a HuCOOH 

 Laurie, CiiH 23 COOH 

 Myristic, C 13 H 27 COOH 

 Palmitic, C 15 H 3 iCOOH 

 Stearic, C 17 H 35 COOH 

 Oleic, C 17 H 33 COOH 



In general, oleic and palmitic acids are present to the greatest 

 extent. The fats from butyric, caproic, caprylic, and oleic 

 acids are liquid. The fats from the other acids are solid. 

 The first three mentioned fatty acids are soluble in water 

 and volatile in steam. All the acids are saturated with the 

 exception of oleic. Milk fat is soluble in the usual solvents: 

 Ether, carbon disulphide, acetone, and liquid hydrocarbons. 



Milk fat occurs in small globules from 1.6 to 10 microns 

 in diameter (0.0016 to 0.01 mm.). They are liquid in the 

 animal, but solid at ordinary temperatures, the melting 

 point varying from 29.5° to 33° C. The fat globules in milk 

 are in the form of a true emulsion — minute, oily particles 

 suspended in a slightly viscous medium (Section 216, II, b), 

 the viscosity of the milk plasma being due to the soluble 

 proteins. Referring to the specific gravity of milk, it may 

 be noted that an increase in the amount of fat causes a 

 lowering of the specific gravity. 



(c) Proteins consist of caseinogen, lactalbumin, and one 

 or two others not of sufficient importance to deserve 

 mention. Caseinogen helps to give the opaque color to 

 milk, being present in a condition of pseudosolution. It 

 contains sulphur and phosphorus in addition to the ordinary 

 protein elements, carbon, hydrogen, nitrogen, and oxygen, 

 and is probably combined with calcium or with calcium 

 phosphate. Acids precipitate the casein by removing the 

 calcium, thus setting free the protein proper. The action of 

 rennin in precipitating casein is somewhat different. It splits 

 the caseinogen into two different soluble proteins, at the 

 same time liberating the calcium phosphate. One of the 



