Hydrogen peroxide-induced changes in activities of membrane lipids-degrading enzymes and contents of membrane lipids composition in relation to pulp breakdown of longan fruit during storage

This study aimed to investigate the effect of hydrogen peroxide (H2O2) on membrane lipids metabolism and its relation to pulp breakdown development of longan fruit during postharvest storage. Compared to the control longans, H2O2-treated longans showed higher pulp breakdown index, cell membrane permeability, and activities of phospholipase D (PLD), lipase and lipoxygenase (LOX). Moreover, H2O2-treated longans maintained higher levels of pulp phosphatidic acid (PA) and saturated fatty acids (SFA). However, H2O2-treated longans exhibited lower levels of pulp phosphatidylcholine (PC), phosphatidylinositol (PI) and unsaturated fatty acids (USFA), lower index of unsaturated fatty acids (IUFA), and lower ratio of USFA to SFA (U/S). These findings demonstrated that H2O2 caused the increased activities of enzymes involving in membrane lipids degradation and the accelerated decompositions of membrane USFA and phospholipids in longan pulp, which eventually triggered the destruction of the pulp cell membrane structure and the development of pulp breakdown in longans during storage.