Abstract: In order to investigate the effect of pre-harvest spraying of diethyl aminoethyl hexanoate (DA-6) on membrane lipid metabolism in the pericarp of longan fruit during postharvest storage, ‘Fuyan’ longan (Dimocarpus longan Lour. cv. Fuyan) were sprayed with 10 mg/kg DA-6 or distilled water (as the control) once at 70, 90 and 110 days after full bloom. The fruit were harvested at 120 days, and they were selected, cleaned and dried prior to packaging in 0.015 mm thick polyethylene bags (50 fruits per bag, 50 bags per group) and subsequent storage at (28 ± 1) ℃ and 85% relative humidity. The results showed that compared with the control fruit, pre-harvest spraying of DA-6 could retard the increase in cell membrane permeability, reduce the activity of membrane lipid-degrading enzymes such as lipoxygenase (LOX), lipase and phospolipase D (PLD), maintain higher contents of phosphatidylcholine (PC) and phosphatidylinositol (PI), higher index of unsaturated fatty acids (IUFA) and relative degree of unsaturation of fatty acids (U/S), but lower content of phosphatidic acid (PA) in the pericarp of harvested longan fruit during storage. Therefore, pre-harvest spraying of DA-6 could delay the degradation of unsaturated fatty acids (oleic acid (C18:1), linoletic acid (C18:2) and linolenic acid (C18:3)) of cellular membrane lipids, which were beneficial to maintain the cellular structure. From these results, it could be concluded that improved longan fruit storability by pre-harvest spraying of DA-6 may be related to effectively alleviated membrane lipid metabolism in the pericarp of longan fruit during postharvest storage.

Key words: longan fruit, storability, diethyl aminoethyl hexanoate, membrane lipid metabolism, membrane lipid-degrading enzymes, membrane lipid composition