418 



ANIMAL BIOCHEMISTRY 



which discourage the growth of putrefactive organisms. Lactic acid 

 also promotes the utilization of calcium and phosphorus by increasing 

 the intestinal absorption of these important mineral elements. 



Milk characteristically contains mineral salts in approximately the 

 same proportions as in the body of a newborn animal. Milk ash 

 contains potassium, calcium, sodium, magnesium, phosphorus, chlo- 

 rine, and sulfur, as well as traces of copper, iron, zinc, aluminum, 

 manganese, and iodine. Citric and carbonic acids are important, 

 combining with bases to form salts. The other anions of milk are 

 chloride and phosphate. 



Lecithin and cholesterol are also normal milk constituents. The 

 former ranges from 0.03 to 0.05 per cent whereas the latter fluctuates 

 with the fat and may vary from 0.01 to 0.02 per cent. 



TABLE 16—7. Approximate Composition of Some Important Milk Products 



(Expressed in Per Cent) 



