柿果实采后胞壁多糖代谢及其降解酶活性的变化

Changes of Cell-wall Polysaccharides and Their Catabolic Enzyme Activities of Persimmon Fruits during Post-harvest

以富平尖柿为试验材料,研究了室温下柿果实硬度和细胞壁组分及其降解酶活性变化.结果表明,柿采后后熟期间果肉硬度持续下降,平均日下降3.1% ,其中第7天到第16天下降最快,平均日下降6 .9% .碳酸钠可溶果胶 SSP 和2 4 % KOH可溶组分含量持续下降,与果肉硬度变化呈极显著正相关 r分别为0 .96 98和0 .80 84 ;而水溶性果胶 WSP 和4 % KOH可溶组分含量不断上升,与果肉硬度变化呈极显著负相关 r分别为- 0 .95 6 6和- 0 .9392 ,螯合剂可溶果胶 CSP 与2 4 % KOH不溶组分含量变化缓慢.多聚半乳糖醛酸酶 PG 和纤维素酶Cx 活性均在采后第16天达最高值.相关性分析表明,PG活性上升可能是导致柿SSP含量下降和WSP含量上升的主要原因;而Cx活性则可能引起纤维素以及难溶性的半纤维素 2 4 % KOH可溶组分 向易溶的半纤维素4 % KOH可溶组分 转化,从而导致了柿果肉硬度的下降.

The fruits of the persimmon variety Jianshi (Diospyros kaki L. f. cv. Fuping Jianshi),planted in the Fuping Xian County,were used to study the firmness and the cell-wall components and their catabolic enzyme activities of post-harvest persimmon fruits at room temperature.The results showed that after the fruits were harvested,the firmness of their flesh continuously declined with its average daily decrement reaching 3.1% and its quickest decrease taking place averagely at 6.3% per day between the seventh day and sixteenth day of post harvest.The contents of sodium carbonate soluble pectin and 24% KOH soluble components continuously decreased,and showed an extremely significant positive correlation with the flesh firmness (with r at 0.969 8 and 0.808 4,respectively).Contrarily,the contents of water-soluble pectin and 4% KOH soluble components continuously increased and showed an extremely significant negative correlation with the flesh firmness(with r at 0.956 6 and 0.939 2,respectively).Furthermore,the contents of chelator-soluble pectin and 24% KOH insoluble components varied slowly.The activities of both polygalaeturonase (PG) and cellulase(Cx) peaked on the sixteenth day of post harvest.It was showed in correlation analysis that increased PG activity probably was the major reason to result in decreased SSP and increased WSP and increased Cx activity probably caused cellulose and poorly soluble hemicellulose to transform into easily soluble hemicellulose(a 4% KOH soluble component),thereby leading to decreased flesh firmness.