A study of the physiological changes and the nutritional qualities of irradiated apples and the effect of irradiation on apples stored at room temperature

The effects of γ-irradiation on the metabolism and nutritional qualities of cold Delicious apples and on the lethality of verticillate pathogenic fungi have been studied. The storage effect of irradiation on apples at room temperature has been observed. The results showed that the respiratory intensity of irradiated apple at 0.3–0.5 kGy was near or lower than that of unirradiated apple after 15 days irradiation. The amount of ethylene release was obviously inhibited when fruits were irradiated with 0.3–0.7 kGy. The flesh firmness of apple irradiated with 0.3–0.9 kGy was higher than that of unirradiated apple with the increasing of storage time. The negative correlations between the flesh firmness and the activities of pectinesterase (PE), polygalacturonase (PG) were observed when the dosage was lower than 1.5 kGy. The 2.0 kGy irradiation damaged the ultrastructure of cells, induced the softening of apple. When apples were irradiated with 0.7–2.0 kGy, the contents of 4 important volatile components of apple would be decreased. However, the dosage mentioned above had no effects on the pure chemicals. The studies showed that there was no significant effect of irradiation with 0.3–2.0 kGy on the nutritional qualities of apples and this dosage range could effectively control the verticillate pathogenic fungi. The result of storage experiments showed that the rotting fruits were obviously decreased by 0.3–0.9 kGy irradiation.