Studies on Maturation Changes in Fruits Induced by Ionizing Radiation.

Part III Effect of gamma radiation on the ripening and the keeping quality of astringent perssimon

Abstract

Astringent perssimons (Diospyros kaki L.) were irradiated at 0.15×10⁶-4.0×10⁶r with gamma rays from Co⁶⁰ at the rate of 0.25×10⁶r/hr. At the doses of 0.15×10⁶-0.25×10⁶r, the fruits ripened 3-5 days after irradiation, and they became soft and less astringent with the advance of ripening. Tannin content of the ripening fruits decreased considerably by irradiation. On some varieties, the extent of such changes was less at 1.0×10⁶r than the lower dose level described above. The fruits irradiated at 2.0×10⁶ and 4.0×10⁶r had almost no astringency immediately after irradiation, and they became very soft and darkened. Ascorbic acid in irradiated fruits decreased during storage. The composition of free amino acids determined by thin layer chromatography seemed to be unaffected by irradiation. Carbon dioxide evolution rate of irradiated fruits temporarily increased immediately after irradiation, and decreased thereafter. This initial increase was proportional to the dose level up to 1.0×10⁶r.