Effect of UV-B irradiation on chlorophyll-degrading enzyme activities and postharvest quality in stored lime (Citrus latifolia Tan.) fruit

UV-B irradiation was applied to lime fruit to investigate its effect on chlorophyll (Chl)-degrading enzyme activities and postharvest quality during storage. Mature green lime fruit were irradiated with or without UV-B doses at 19.0 kJ m−2 and then stored at 25 °C in darkness. UV-B treatment efficiently delayed the decrease of hue angle values and Chl a contents. The activities of the Chl-degrading enzymes, chlorophyllase, Chl-degrading peroxidase and pheophytinase in the fruit with UV-B treatment were suppressed and Mg-dechelation activity was also retarded by the treatment. UV-B treatment induced a gradual increase in citric acid and suppressed the increase of sugar contents during storage. In addition, the ascorbic acid content with or without UV-B treatment decreased during storage, but the decrease in the control was faster than that with UV-B treatment. We concluded that UV-B treatment effectively suppressed chlorophyll degradation through the control of chlorophyll-degrading enzyme action and the changes in quality in mature green lime during storage.

► UV-B treatment was effective in retarding degreening in green lime fruit during storage.
► UV-B treatment suppressed chlorophyll degradation through the control of activities of the chlorophyll-degrading enzymes, chlorophyllase, chlorophyll-degrading peroxidase, pheophytinase and Mg-dechelation.
► Quality of lime fruit treated with UV-B was maintained during storage.