Water stress affects on cell membrane lipid oxidation and calcification of chestnut (Castanea mollissima Bl.)

Abstract

Calcification, a kind of quality deterioration, occurs in chestnut due to fast water loss when stored at low relative humidity (RH) and room temperature. In this study, the relationship between water loss rate and plasma membrane lipid oxidation in chestnut stored at low (50–55%) RH and high (85–90%) RH at 25°C has been investigated to understand the mechanism of calcification. Water loss rate per day in chestnut at low RH was 6% and 1.5 times that at high RH, while the calcification index at low RH was 0.4 and 3.5 times that at high RH. At low RH, the activities of plasma membrane lipase and lipoxygenase (LOX), the content of malonaldehyde (MDA) and saturated fatty acid (SFA) in chestnut were higher than those at high RH. Meanwhile, unsaturated fatty acid (UFA) index decreased in low RH, but increased in high RH. The correlation coefficient (r) between MDA content and calcification index in chestnut stored at low RH and high RH was 0.928** and 0.937** respectively, which implied that the plasma membrane lipid oxidation induced by fast water loss might be related closely to occurrence of calcification in chestnut. In contrast, at high RH, the moisture content in chestnut decreased slowly and the hydrolysis and oxidation of membrane lipid were a low, and was associated with better maintenance of quality.