THE CHEMISTRY OF FOOD. 



Gi 



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 sweeteu- 

 ; ng power. 



25. Starch. This is the most widely distributed of 

 the vegetable principles. 

 It is tasteless, inodorous, 

 and does not crystallize. 

 It consists of minute 

 rounded granules, which, 

 under the microscope, 

 reveal a somewhat uni- 

 form structure (Fig. 15). 

 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. 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 eaten uncooked; 

 for the grains of raw starch are but slightly acted upon 

 within the body. But, under the potent chemistry of the 

 sun's ray, this crude material is converted into sugar. 

 Thus are the fruits prepared by the careful hand of 

 Nature, so that when ripe they may be freely used without 

 further preparation. 



27. Gum is commonly found in those articles which 



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

 solubility ? 



26. How much starch in bread-stuffs ? In rice ? Unrine fruits? Ripe fruits? 



27. Gum, where found ? Its composition ? Gum Arabic- ? 



FIG. 15. GRANULES OF POTATO STAHCH. 



