Low Dose Gamma Irradiation Does Not Affect the Quality or Total Ascorbic Acid Concentration of "Sweetheart" Passionfruit (Passiflora edulis)

Effect of Phytosanitary Irradiation Treatment on the Storage Life of ‘Jiro’ Persimmons at 15 °C

Irradiation is becoming a more accepted phytosanitary market access treatment for some international horticultural trades. However, there is little information on the effects of phytosanitary irradiation treatment on persimmon fruit quality. ‘Jiro’ persimmon fruit were treated with an average of 769 Gray (Gy) at a commercial phytosanitary irradiation X-ray facility to examine the effect of this market access treatment on fruit quality during storage. After treatment, fruit were stored in air at 15 °C for up to three weeks. The results showed that, in general, there was no effect of irradiation treatment on fruit weight loss, calyx appearance, fruit firmness (objective and subjective), total soluble solids (TSS), titratable acidity (TA), internal appearance, and ethylene production rate. There were some treatment differences in fruit respiration rates and some aspects of fruit appearance and colour, where irradiated fruit had higher respiration rates and were slightly darker with higher levels of skin blemish, although these measured differences were not commercially significant. This study showed the promise of using low dose irradiation as a phytosanitary treatment for ‘Jiro’ persimmons, but more work is required to test other persimmon cultivars and other storage and marketing environments.

Postharvest Control of Botrytis cinerea and Monilinia fructigena in Apples by Gamma Irradiation Combined with Fumigation

To extend the shelf life of apples in South Korea, we evaluated the effect of gamma irradiation alone or gamma irradiation combined with fumigation on the control of postharvest decay caused by Botrytis cinerea and Monilinia fructigena. An irradiation dose of 1.0 kGy caused the maximal inhibition of B. cinerea and M. fructigena spore germination. The gamma irradiation dose required to reduce the spore germination by 90% was 0.76 and 0.78 kGy for B. cinerea and M. fructigena, respectively. Inhibition of conidial germination of both fungal pathogens occurred at a greater level at the doses of 0.2 to 1.0 kGy compared with the nontreated control; 0.2 kGy caused 90.5 and 73.9% inhibition of B. cinerea and M. fructigena, respectively. Treatment in vitro with the ecofriendly fumigant ethanedinitrile had a greater effect compared with the nontreated control. The in vitro antifungal effects of the gamma irradiation and fumigation treatments allowed us to further study the effects of the combined treatments. Interestingly, when irradiation was combined with fumigation, the percentage of disease inhibition increased more at lower (<0.4 kGy) than at higher doses of irradiation, suggesting that the combined treatments reduced the necessary irradiation dose in phytosanitary irradiation processing under storage conditions.