Effects of gamma radiation on decay, some chemical compositions and quality of strawberries

The strawberry cultivars used were Kogyoku and Danner. They were sealed in the polyethylene bags (0.03mm in thickness) and were irradiated with Co 60 gamma rays at 125, 250, 500 and 1000 Krads.The storage temperatures were at room temperature and 1-5°C. The decay of partially green strawberries (Stage I) tended to be less than that of uniformly red ones (Stage II). The concentration of CO2 and O2 in a polyethylene bag during the storage were approximately 4-6% and 6-8% respectively, except for high dose level. The contents of anthocyanins and ascorbic acid decreased with higher doses immediately after irradiation. These compositions in the Irradiated berries increased temporarily at low temperature storage and the subsequent changes showed almost same tendency to decrease as those in unirradiated berries. A degradation of protopetin to soluble pectin evidently occurred in the irradiated berries of Stage I immediately after irradiation. The further decrease of protopectin was less in the irradiated berries than in unirradiated ones. There were no differences between sugar contents in irradiated and unirradiated berries. The titratable acidity in the irradiated Stage I-berries at high dose of radiation apparently decreased during the storage of at room temperature.The organoleptic evaluation indicated that irradiation over the dose of 500 Krad caused more deterioration of the qualities in both stage berries immediately after irradiation and during the storage, while there were no changes of the qualities in the berries which were irradiated at the dose of 250 Krad or less.