Effect of postharvest UV-C irradiation and DPI treatment on some biochemical characteristics of sweet pepper fruits (Capsicum annuum var. Nirvin) during storage

Sweet pepper is one of the most important commercial vegetable with short postharvest life and high susceptibility to fungal diseases. This research was conducted based on complete randomized factorial design with two treatments of UV-C radiation (0, 5 and 10 kJ m-2s-1) and DPI dipping (0 and 1 µM) with 3 replication on sweet pepper fruits. The effects of these treatments was studied on some attributes changes throughout 28 days at 7ºC. The results showed that carotenoid content reduced during 28 days of storage. Treatment of 5 kJ m-2s-1 UV-C and combination of 10 kJ m-2s-1 and DPI treatment caused an increase in carotenoid content that generally kept the same values than initial value after 28 days at 7 ºC. After 10 kJ UV-C m-2 treatment an important initial stress was foundand treated samples conserved antioxidant contents regarding the initial content. In these samples DPI dipping generally reduced the antioxidant capacity on the 28 day.  The medium illumination dose showed the highest total phenolics content and reducing sugar. Combination of 10 kJ UV-C m-2 illumination and DPI treatment caused conservation of protein content after 28 days at 7 ºC. SOD activity increased on 21th day of storage in treated samples with 5 kJ m-2s-1 UV-C and 1 µM DPI[RbD1] . 10 kJ UV-C m-2 caused an increase in catalase activity on the last day of storage. Illuminated samples with 5 kJ UV-C m-2 showed the highest peroxidase activity on 14th day at 7 ºC. As main conclusion a pretreatment of UV-C radiation and DPI dipping was found as an effective technique for quality preservation of sweet pepper fruits during storage. [RbD1]Which concentration?