Effects of heat treatment on internal browning and membrane fatty acid in loquat fruit in response to chilling stress

Abstract

Chilling injury (CI) limits the storage period and shelf-life of red-fleshed loquat fruit (Eriobotrya japonica Lindl.), which leads to a remarkable loss after cold storage. To develop an effective technique to reduce CI, the effects of a 38 degrees C heat treatment in air for 5 h, plus storage at 1 degrees C for 35 days, on internal browning (IB) and membrane fatty acid composition of the loquat cv. Jiefangzhong were investigated.Heat treatment delayed the occurrence of IB and inhibited the increase of IB index in 'Jiefangzhong' loquat fruit. Heat treatment maintained lower levels of electrolyte leakage and malondialdehyde content, and inhibited the increases in phospholipase D and lipoxygenase activities compared with the control fruit. Meanwhile, heat treatment inhibited the increases in palmitic, stearic and oleic acid levels and delayed the decreases in linoleic and linolenic acid contents, thus maintaining higher unsaturated/saturated fatty acid ratio than the control.These results suggest that the reduction of IB in chilled loquat fruit by heat treatment might due to maintenance of membrane integrity and higher unsaturated/saturated fatty acid ratio.