314 AGRICULTURAL CHEMISTRY 



a better balanced food. The 10 per cent, of dry matter 

 in mangels is a little more than half starch and contains 

 about i. 40 per cent, of crude protein of which half is pro- 

 tein. Mangels also contain about i per cent, each of ash 

 and fiber and a small amount of fat. 



428. Apples vary in composition with the variety and 

 physical characteristics. They contain from 10 to 16 per 

 cent, solids, of which 75 per cent, is sugar or allied carbo- 

 hydrates, and about half a per cent, each is fat and protein. 

 Among the organic acids, malic predominates. The 

 flavor and special characteristics depend upon the relative 

 amounts of the different sugars, as sucrose, levulose and 

 dextrose, and the organic acids and essential oils which 

 the apples contain. It is these compounds which give 

 individuality to apples. 



429. Oranges contain from 10 to 15 per cent, of solid 

 matter, the larger portion ( 80 per cent. ) being sugar. 

 The citric acid content ranges from i to 2.5 per cent, in 

 different varieties. The amount of protein, fat and fiber 

 is small. The ash or mineral matter averages about one- 

 half per cent, and is composed mainly of potash and lime 

 with smaller amounts of other compounds. The iron and 

 sulfur content in some kinds of oranges is larger than is 

 ordinarily found in other fruits. In average oranges, 

 the physical composition is as follows : Rind, 20 to 30 

 per cent. ; pulp, 25 to 35 per cent. ; and juice, 35 to 50 

 per cent. 



430. Lemons differ from oranges in containing larger 

 amounts of citric acid and smaller amounts of sucrose, 



