Suppression of Chlorophyll Breakdown and Quality Changes by Hot Water Treatment of ‘Pichit 1’ Lime (Citrus aurantifolia Swingle) Fruit

抄録

Hot water treatment (HWT) was applied to a new Thai lime cultivar fruit, ‘Pichit 1’ (Citrus aurantifolia Swingle) to investigate its effect on chlorophyll (Chl) degradation and postharvest quality during storage. Fruit were treated with HWT with temperatures of 45, 48 or 50°C for 3, 5, and 10 min and then kept in the dark at 25°C and 90 ± 5% RH. Lime peels retained a greener color after HWT at 48°C for 5 min compared to the fruit given any other treatment. HWT at 48°C for 5 min efficiently delayed the decrease in the hue angle value acquired during storage. Chlorophyllide a, pheophorbide a, pyropheophorbide a, 13²-hydroxychlorophyll a, pheophytin a, and an unknown catabolite, which may be a chlorophyllide a derivative, were detected as Chl derivatives in the fresh limes. The levels of chlorophyllide a, pheophytin a, and 13²-hydroxychlorophyll a gradually decreased during the progression of peel degreening. Those derivative levels were higher in the fruit treated with HWT than the control. Moreover, the organic acid content was maintained at higher levels in the fruit treated with HWT than the control during storage at 25°C. During storage, the sugar content was seen to decrease with or without HWT; however, sugar reduction in the control was more rapid. It appeared that HWT reduced the degradation of Chl by controlling its catabolites. Therefore, HWT affected the fruit quality of green ‘Pichit 1’ limes in storage.