采后雪梨衰老与过氧化作用

雪梨衰老时，硬度下降，果肉褐变糠化，失去组织感；果实雨二醛含量增加，质膜透性增大，过氧化物含量先逐渐下降，末期又有升高现象，并且果心比果肉中的过氧化物含量高。果肉过氧化氢酶活性明显高于果心，先出现高峰后下降，至组织败坏时又升高；果心的过氧化氢酶活性在初期极低，随衰老褐心的出现后又明显升高。

Senescence and Peroxidation in Postharvest ‘Xue Hua’ Pears

During the senescence of ‘Xue Hua’ Pears, the fruit firmness declined with the flesh developing the squarrose and browning, and lacking structural sense. The malonaldehyde (MDA) content increased gradually. The content of peroxidate decreased gradually at first but increased at end,and it was more in core than that in flesh. The activity of catalase (CAT) in flesh was higher than that in core, which decreased after its peak appeared; however, it increased as the tissue damaged. The activity of CAT in core was lower at first, and increased significantly as the core turn up browning and senescence. There were lower firmess and CAT activity, higher MDA content and permeability of plasma membrane in the flesh of the squarrose than those of normal one.