FOODS 



87 



TABLE OF INFANT FOODS (HUTCHISON). 



BUTTER. 



Butter is the fat of milk clotted together by shaking or 

 beating at a low temperature. A thin bluish fluid separates, 

 which is called buttermilk. Butter consists of neutral fats 

 mixed with water, a small amount of casein, and traces of 

 salts, and there may be added salt (NaCl). The average 

 composition is : Fat, 78 to 94 per cent ; water, 8 to 12 per 

 cent ; curd, i to 3 per cent ; salt, o to 7 per cent. The fats 

 are present as glycerides of certain fatty acids, namely : 

 butyric, caproic, caprylic, capric, myristic, palmitic, 

 steanc, and oleic acids. The first four are soluble in hot 

 water, and are known as the " soluble fatty acids," the 

 rest as the " insoluble fatty acids." Bell's analysis of 

 butter fat is : butyric acid, 6-1 per cent ; caproic, caprylic, 

 and capric acids, 2-* per cent ; myristic, palmitic, and 

 stearic acids, 49-4 per cent ; oleic acid, 36-1 per cent ; 

 glycerol (calculated), 12-5 per cent. These are present chiefly 

 as tributyrin, tripalmitin, and triolein (: C 3 H 5 (O-C 4 H -O) 3 : 

 C 3 H 5 (O.C 16 H 31 0) 3 : C 3 H 5 (O.C 18 H 33 0) 3 :). 



ADULTERATIONS. The important ones are : Addition 

 of water in excess, the substitution of foreign fats, salt in 

 excess, starch, boric acid. 



EXAMINATION OF BUTTER FOR WATER, SALT, CURD, 

 FAT, AND BORIC ACID. 



The fat is further examined by the Valenta test, for 

 specific gravity, for volatile fatty acids, for fixed fatty 



