Volume 14 . . Number i 



The Plant World 



A Magazine of General Botany 

 JANUARY, 1911 



THE BEHAVIOR OF TANNIN IN PERSIMMONS, WITH 

 SOME NOTES ON RIPENING. * 



Francis E. Lloyd. 



Perhaps no phenomenon of ripening is so obviously remark- 

 able as the apparent disappearance of tannin during this period. 

 Within a few days, or even a few hours, uneatable astringent 

 fruits, — of which the persimmon is a proverbially familiar 

 example, — become fit for the palate. Another example, which 

 has been studied chiefly by Vinson (1907, 1910) and by myself 

 (1910), is the date. This fruit contains a notable quantity of 

 tannin laid down chieflly in a definite zone at the outer limits 

 of the mesocarp. The position of this tannin makes it possible 

 to render it tasteles in a short period by treatment with the fumes 

 of vinegar, a method practiced by the Arabs; and Vinson has 

 found that the same result may be had by means of numerous 

 substances. The persimmon is also ripened artificially by the 

 Japanese (Fairchild, 1905) so far in advance of the natural course 

 of events that, in place of a soft, mushy, or watery fruit, one of 

 the consistency of an apple is obtained, which is similar y peeled 

 and eaten. A fully developed, well-colored, but still hard and 

 unripe fruit, has, indeed, a fragrance suggestive of the apple, 

 and one can easily imagine the fruit in this condition without the 

 astringencv ,to be quite desirable. While probably not the only 

 change which ensues under the Japanese method of treatment, 

 the elimination of the tannin is the sine qua non of the process. 



♦This work should be considered a continuation of that on the date begun at the Arizona 

 Experiment Station, as part of an Adams Kund project, and continued at the Agricultural 

 Experiment Station of the Alabama rdytechnic Institute. 



