Effects of heat treatment on postharvest physiology and storage quality of longan fruits

Effects of hot water treatment on postharvest physiology and storage quality of longan (Dimocarpus longan Lour.) fruits were investigated. The longan fruits were treated with hot water at 50°C for 10 minutes. The fruits were dried prior to packaging and stored at (15 ± 1)°C. During fruit storage, fruit respiration rate, cell membrane relative leakage rate in pericarp, contents of malondialdehyde (MDA), chlorophyll, carotenoid, anthocyanin, flavonoid and total phe-nolics in pericarp, contents of total soluble solids(TSS), titratable acid(TA), soluble sugar, reducing sugar and vitamin C in pulp, pericarp browning index and aril breakdown index of harvested longan fruits were determined. The results showed that compared with the control fruits, the treatments with hot-water could effectively reduce fruit respiration rate, decrease fruit weight loss, delay the increase of MDA content and cell membrane relative leakage rate in pericarp, keep higher contents of chlorophyll, carotenoid, anthocyanin, flavonoid and total phenolics in pericarp, and higher contents of pulp nutritional ingredients such as TSS, TA, soluble sugar, reducing sugar and vitamin C, decrease pericarp browning index and aril breakdown index. From the results it can be concluded that hot water treatment at 50°C for 10 minutes can effectively delay fruit senescence, increase fruit quality of harvested longan fruits.