536 MISCELLANEOUS FARM SUBJECTS 



The protein compounds are most abundant in some of the animal 

 foods, as lean meat, though the cereals contain them in consider- 

 able, and peas and beans in large proportions. The gelatinoids are 

 less valuable than the albuminoids for nutriment. 



The extractives are included with the protein compounds be- 

 cause they contain nitrogen, but they differ greatly from the albu- 

 minoids and gelatinoids. They are the principal ingredients of 

 meat extracts, beef tea, etc. They are believed to neither build 

 tissue nor furnish energy, but to act as stimulants and appetizers. 

 The craving which some persons have for meat is perhaps due in 

 part to a desire for these extractives. The nitrogenous compounds 

 of potatoes and other vegetable foods contain substances similar to 

 the extractives of meat, and like them can not build tissue, and 

 hence have an inferior nutritive value. 



Fats. Fats occur chiefly in animal foods, as meats, fish, butter, 

 etc. They are also abundant in some vegetable products, such as 

 olives and cotton seed, from which they are expressed as oil, and 

 occur in considerable quantities in some cereals, notably oatmeal 

 and maize (whole kernel), and in various nuts. In our bodies and 

 those of animals fats occur in masses under the skin and in other 

 localities, and in minute particles scattered through the various 

 tissues. The amount of fat in the body varies greatly with food, 

 exercise, age, and other conditions. When more food is taken than 

 is necessary for immediate use part of the surplus may be stored 

 in the body. The protein and fat of food may thus become body 

 protein and body fat; sugar and starch of food are changed to fat 

 in the body and stored as such. When the food supply is short this 

 reserve material is drawn upon for fuel. Fat forms about 15 per 

 cent, by weight, of the body of an average man. 



Carbohydrates. These are so called because they contain both 

 carbon and hydrogen. They include such compounds as starches, 

 different kinds of sugar, and the fiber of plants or cellulose. They 

 are found chiefly in the vegetable foods, like cereal grains and po- 

 totoes ; milk, however, contains considerable amounts of milk sugar, 

 which is carbohydrate. The carbohydrates form only a very small 

 proportion of the body tissues less than 1 per cent. Starches and 

 sugars, which are very abundant in ordinary food materials, are im- 

 portant food ingredients, because they form an abundant source of 

 energy and are easily digested. They may be and often are trans- 

 formed into fat in the body. 



Refuse. Food, as bought at the market or even as it is served 

 on the table, contains more or less of materials which can not be or is 

 not eaten, such as the bones of meat and fish, the shells of eggs, and 

 the skins and seeds of fruits and vegetables. In discussing the chem- 

 ical composition of foods such portions are usually counted as re- 

 fuse, but they make an important item when the actual cost of the 

 nutrients of food is considered. Refuse contains in part, the same 

 ingredients as the edible portion, though usually in very different 



