Kansan Academy of Science. 153 



ON THE OCCURRENCE OF STARCH IN GREEN FRUITS. 



K. H. S. B.UT.KY and W. S. LoNii. 



IT IS well to remember at the outset that the chief source 

 of the vegetable food of man is the seeds, seed receptacles, 

 and roots of plants. In making arrangements to reproduce its 

 kind, roots, tubers, seeds, fruits and vegetables each has its 

 own way of attaining the desired result. In tubers, lil;e ll e 

 potato, there is a great storehouse of starch and oth.er nutri- 

 ents, and on this the young plant lives until it finds suitable 

 soil in which to grow and continue an independent existence. 

 Grains consist of a storehouse for starch and other nutrients 

 to start the young plant. Some roots, as the beet, containing 

 starch and sugar, have been cultivated for their sugar content, 

 and very much improved in this particular. Fruits, as they 

 ripen, change in composition ; the starch is changed to sugar, 

 the harsh tannic acid is replaced by sugar, and the fruit acid — 

 malic, citric, or tartaric — is often much diminished in quantity. 

 These changes are well shown in the analysis of Baldwin apples 

 as published by the Pennsylvania department of agriculture: 



Very green. Green. Ripe. Overripe. 



Invei-t sugar 6.40 6.46 7.70 8.81 



Sucrose 1 . 63 4.05 6.81 5 . 26 



Total sugar by addition 8.03 10.51 14.51 14.07 



Starch 4.14 3.67 0.17 



The free malic acid in the ''very green" apples was 1.14 

 percent, and in the overripe apples only 0.48 percent. 



Some interesting experiments on the persimmon were made 

 by tl\e Bureau of Chemistry of the Department of Agriculture. 

 The astringent taste of the green persimmon is due to the 

 presence of tannic acid, which in the process of ripening is 

 probably changed to sugar. It was learned that the Japanese 

 ripen persimmons artificially by putting them into an empty 

 "Saki" cask, from which the beer has been recently removed. 

 A few lumps of dry starch are also placed in the cask. A study 

 of this process revealed the fact that the ripening was due to 

 the carbon dioxide which remained in the cask, and the starch 

 removed the excess of moisture. So this fruit can now be and 

 is successfully ripened in an atmosphere of carbon dioxide. 



