IMPORTANT FOODSTUFFS, IMPORTANT TISSUES 133 



about 1% of protein, on an average of 3% salts and from 10- 

 15% water. It contains practically no carbohydrate. Butter 

 is an excellent source of vitamine. Oleomargarine, a butter sub- 

 stitute made largely from beef fat also has been discussed in the 

 chapter on fats. 



Cheese. When the caseinogen of milk is clotted by rennin 

 it separates out as a solid curd, which carries .with it much of 

 the milk fat. This curd when filtered off is called "cream 

 cheese." From it, by pressing and other processes cheeses of 

 various kinds are made. Cheese is a very nutritious foodstuff. 

 Different kinds of cheese vary greatly in composition and food 

 value. Average American cheese contains about 29% protein, 

 36% fat, traces of carbohydrate, 3.5% ash and 32% water. 



Meats. Meats are important food substances, for they fur- 

 nish large amounts of proteins, which are essential constitu- 

 ents of the diet. Meats contain a variety of proteins, but the 

 chief protein of dead muscle is myosin. Albumin, globulins 

 other than myosin, albuminoids, glycoproteins, nucleoproteins, 

 hemoglobin derivatives, and lecithoproteins all are constitu- 

 ents of meat, but in digestion all of these substances are broken 

 up into their constituent amino acids, the form in which pro- 

 tein food reaches the cells of the tissues. Meat also contains 

 fats, and small amounts of the carbohydrate glycogen or the 

 sugar derived from it. Most meats, with the exception of bacon 

 or very fat meats contain from 10 to 20% protein. Fat ranges 

 from a few per cent up to 60% in fat bacon. Ash ranges from 

 about 1% to 4 or 5%, water from about 7 or 8% to 68 or 70%. 



Eggs. Eggs are a very important article of diet. In the 

 development of the young of birds they furnish the material 

 out of which the tissues of the chick are built up. Eggs con- 

 tain (without the shell) about 12% protein, 11% fat, 0.5% 

 carbohydrate, 1% ash, and 75% water. Most of the fat is in 

 the yolk. About % of the protein is in the white and 

 % in the yolk. About 90% of the total protein of the white is 

 albumin. About 61/2% is globulin. Vitellin is the chief yolk 

 protein. All of these substances have been considered under 



