Use of Gamma Irradiation for the Extended Commercial Storage of Philippine Onions and Other Agricultural Produce

The paper reports the results of investigations on the use of irradiation to inhibit sprouting and other storage disorders in onions and garlic during commercial storage. A dose of 3—10 krad inhibited sprouting in Yellow Grannex onions during refrigerated storage. In addition, it also had a beneficial effect simultaneously decreasing mould growth, decay and loss in weight during storage. Irradiation appears to predispose the bulbs to chilling injury but the onset and progress of this defect occurs at a time when the onions have reached their maximum storage life (i.e. total defects = 50%). Time of harvest and general condition of the bulbs at harvest appear to have a significant effect on storability and the effects of these variables await further study. Preliminary results indicate that a dose rate of 30 krad/h rather than 5 krad/h has a significant effect on the potential benefits of irradiation. A maximum storage of 6 months as against 4 months for controls is attained with a dose of 3 - 9 krad at a dose rate of 30 krad/h. A dose of 10 krad and dose rate of 25 krad/h produced lower storage defects. Garlic irradiated with 14—26 krad at a dose rate of 25 krad/h can be stored for a maximum period of 12 months in refrigerated storage as against 4 months under ambient storage. A preliminary cost analysis on the effect of irradiation on stored onions and garlic is also discussed. (author)