86 



THE CHEMISTRY OF FOOD 



of sugar are, its power to crystallize when evaporated from 

 watery solutions, such as the juices of many plants; a ten- 

 dency to ferment, by which process alcohol is produced ; and a 

 ready solubility in water. This latter quality renders it Tery 

 easy of digestion, and more so than any other of the saccharine 

 group. It is computed that the annual production of sugar, in 

 all parts of the world, is more than one million of tons. The 

 kind of sugar that is in ordinary use, in this country, is pre- 

 pared from the juice of the sugar-cane, which contains eighteen 

 per cent, of sugar. In France it is manufactured from the 

 beet-root, which holds about nine per cent. ; the maple-tree of 

 our climate yields a similar sugar. The sweet taste of fruits 

 is due to the presence of grape-sugar: the white grains seen on 

 raisins belong to this variety. Cane-sugar is more soluble than 

 the latter, and has twice the sweetening power. (Head Note 10.) 

 25. Starch. This is the most widely distributed of the 

 vegetable principles. It is tasteless, inodorous, and does not 



crystallize. It consists of mi- 

 nute rounded granules, which, 

 under the microscope, reveal 

 a somewhat uniform structure 

 (Fig. 21). Starch will not 

 dissolve in cold water, but in 

 boiling water the small grains' 

 burst open, and may then be 

 dissolved and digested. 



26. The bread-stuffs- 

 wheat, corn, and rye flours 

 are more than one-half starch. 



FIG. 21. GBANULES OF POTATO STARCH Rice, which is the " Staff of 



life" to one-third of the 



human family, contains eighty per cent. Unripe fruits have 

 much starch in them, which renders them indigestible when 



10. Why too much Sugar is Injurious. " Sugar is very wholesome, 

 and, as I told you, we want some in our diet. But children will often eat 



25. Starch, how widely distributed ? Its qualities ? Its constituents ? Its solubility ? 



26. How much starch in bread-stuffs ? lu rice ? Unripe fruits ? Bipe fruits ? 



