SECTION III. FOOD PEOTEINS 



ALTHOUGH there are those who consider that animal proteins 

 are both undesirable and unnecessary as foods, it is never- 

 theless true that man is almost universally a carnivorous 

 animal. The animal world provides mankind with one of 

 its chief sources of food, and especially of protein foods. 

 Protein foods are unquestionably essential, and animal 

 protein foods differ chiefly from those of vegetable origin 

 in the fact that they contain generally much more protein. 

 Of the proteins noted in our Introduction, the keratins have 

 no value as foods ; the gelatins have some value as culinary 

 material, but little actual food value ; whilst the albumins 

 comprise practically all the useful animal food proteins. 

 Whilst the actual flesh of animals is the principal source of 

 food proteins both as to quantity and food value other 

 parts of animals, e.g. kidneys, liver, blood, brains, tongue, 

 are used and relished. The most important sources of 

 animal food proteins are from fish, fowl, sheep, cattle, and 

 pigs, the meat from these being roughly in the same sequence 

 as to digestibility. There are, however, many other animals 

 of which the flesh is quite edible, but most of the above are 

 specially farmed and propagated primarily for their food 

 value. 



As the animal food proteins are exceedingly putrescible, 

 they are usually consumed within a short time of the animal 

 being killed. It is perhaps natural, therefore, that many 

 efforts have been made to discover means of preserving 

 such foods. These efforts form the basis of some important 

 industries, and though they can hardly be included as 

 chemical industries, it will not be out of place in this volume 

 to point out that these efforts present analogies with, as 



