桃果实采后贮藏过程中细胞壁多糖的变化

摘要

以'雨花三号'水蜜桃果实为试材,分别在5℃(低温)和20℃(常温)贮藏一段时间后,研究桃果实采后细胞壁多糖降解、硬度以及乙烯释放速率的变化特征.结果表明,乙烯释放高峰明显滞后于果实采后硬度的快速下降期.不同温度下贮藏过程中果实细胞壁多糖变化的对比表明,低温抑制了细胞壁果胶和细胞壁其余组分的变化,从而抑制了果实的软化.富含半乳糖醛酸的果胶主链断裂.果胶和细胞壁其余组分也发生了半乳糖和阿拉伯糖等中性糖的损失,说明果胶和细胞壁其余组分的增溶及其侧链中性糖的降解也是桃果实采后软化的重要因素,这可能是由多种相关多糖降解酶的作用所导致的.但半纤维素多糖中中性糖的降解对桃果实采后软化的进程并没有影响.%Changes in cell wall structure, decrease in tissue firmness and ethylene production in honey peachinvestigated after various storage at 5℃ and at 20℃.The results showed that during storage, the peak of ethylene production lagged significantly behind the rapid softening of peach fruit, which means that it is not ethylene causes the softening of peach fruit. The structural and compositional changes of cell wall of fruits stored at 5℃ and at 20℃ suggested that low temperature storage inhibited the changes in pectins and cell wall materials (CWM)-residue fraction and delayed the softening of peach fruit. Ruptures of the pectic main chains rich in galacturonic acid occurred. Loss of arabinose and galactose was detected both in pectins and CWM-residue.These results suggested that softening of harvested peach fruit involved the solubilization and degradation of side chains of pectin and CWM-residue fraction, which were probably due to the increased activities of cell wall polysaccharide-related enzymes. However, the loss of neutral sugars in hemicellulosic polysaccharides was not correlated with fruit softening.