EFFECTS OF GAMMA-IRRADIATION ON LIPID METABOLIC CHANGES OF POTATO-TUBERS IN RESPONSE TO MECHANICAL INJURY

Linolenic acid contents of glycolipids increased in irradiated potatoes during storage, accompanied by a decrease of linoleic acid. The puncturing of a potato tuber with a needle of a microsyringe caused the similar changes; the elevation of linolenic acid level and decline of linoleic acid were observed within 24 h after puncturing. Irradiation before the puncturing reduced the degree of the increase of linolenic acid in response to the mechanical injury. The rate of [C-13]acetate incorporation into lipid fractions of irradiated tubers was smaller than that of unirradiated tubers, and polyunsaturated fatty acids (linoleic and linolenic acids) of lipid fractions were weakly labeled in irradiated tubers as compared with unirradiated ones. The results in this study indicate that irradiation retards lipid metabolism in response to mechanical injury.