44 MILK AND ITS PRODUCTS AS FOODS 



mechanical use will be made of chemistry as an aid in deter- 

 mining the values of the different foodstuffs and how they may 

 best be combined with each other in the compounding of more 

 economical and complete rations and diets on which animals and 

 man will grow and thrive. At times the biological study of food- 

 stuffs may move in advance of chemistry, as it has already done 

 in discovering the presence in milk-fat of a fat-like or fat-soluble 

 substance, as yet unidentified, which renders this fat al'together 

 superior to other animal and vegetable fats lacking this growth 

 and health -promo ting foodstuff. It is the province of chemistry 

 to ascertain, if possible, what this substance is. The same may 

 be said of a water-soluble substance which is not nearly so limited 

 as to its sources, being present in sufficient quantity in cereal 

 grains and most of the mixed diets. 



CHEMICAL CLASSIFICATION OF MILK AND ITS PRODUCTS 



AS FOODS 



From the chemical standpoint, the constituents of the food 

 material consumed by animals and man are classified under the 

 heads of water, combustible matter and ash, mineral matter or 

 salts all three terms being applied to the last class. 



The combustible matter includes the carbohydrates (such as 

 starches and sugars), the fats (such as milk-fat, olive oil and 

 other plant oils, and meat-fat), and the proteins (such as the curd 

 of milk, the gluten of wheat and the muscle fiber of lean meat). 



The carbohydrates and fats are largely burned to supply 

 heat and energy, and are also used for the making of fat in the 

 body and in milk. 



The proteins are used, in part, for the same purposes as the 

 carbohydrates and fats, but their distinct function, which these 

 latter cannot perform, is that of supplying material for the 

 making of muscle and other body tissue, and the protein of milk. 



The ash or mineral matter is used for making bone, regulating 

 the heart action and the elasticity of the muscles in general, and 

 preventing acidity of the blood and tissues. 



Under the older classification of foods we find that milk 



