28 MANUAL OF MILK PRODUCTS 



.8 to 1.0 per cent and no more sugar is broken down. Milk- 

 sugar is commonly made from whey in connection with cheese- 

 making. 



Citric acid 



Small amounts of citric acid have been found in milk. Ac- 

 cording to Babcock there is about 0.1 per cent in normal milk. 



The mineral constituents or ash 



The mineral elements in milk are very small in amount and 

 less variable than most of the other constituents, constituting 

 approximately three-fourths of 1 per cent of the entire milk. 

 Because of the difficulty of determining accurately the amounts 

 and the form in which these substances exist in milk, the data 

 given by various investigators differ somewhat. The follow- 

 ing represents our present knowledge as to the kinds and 

 amounts of mineral substances in milk : 



Mineral 'Elements in Cow's Milk Expressed in Per Cent (Bab- 

 cock) 



' Potassium oxide . , 0.175 



Sodium oxide . 0.070 



Calcium oxide 0.140 



Magnesium oxide . . . . . . . 0.017 



Iron oxide 0.001 



Sulfur trioxide 0.027 



Phosphoric pentoxide 0.170 



[Chlorine 0.100 



Ash ... . 0.7% 



Leach says, "The ash of milk does not truly represent the 

 mineral content, since, in the process of incineration, the 

 character of some of the constituents is altered by oxidation 

 and otherwise. 



"Expressed in parts to 100, the ash of the typical milk 

 sample would be about as follows : 



