细胞壁酶活性变化对果胶降解及果实软化影响较大。本文以“半边红”李子为原料，研究0 ℃和10 ℃低温贮藏时果胶物质和主要细胞壁多糖降解酶（PE, exo-PG, endo-PG, EG）活性变化，通过相关性研究阐明细胞壁酶活性对果胶降解的影响。结果表明，低温贮藏时，四种细胞壁降解酶活性变化各不相同，较低的温度能够在一定程度上抑制各酶活性。0 ℃和10 ℃温度贮藏时，PE活性变化在5d之后显著差异，exo-PG活性变化在整个贮藏期差异显著。0 ℃和10 ℃贮藏李子endo-PG和EG活性在前10 d贮藏过程中变化差异均不明显。endo-PG和EG活性变化趋势接近，且endo-PG活性峰值出现比EG晚。相关性分析表明，原果胶和SSP与WSP含量变化显著负相关；PE活性与ASP和HSP含量变化显著正相关，PG对原果胶和SSP向WSP转化的过程中起到较为重要的作用。EG对李子果胶降解的影响作用不大。

Changes in cell wall enzyme activity are known to significantly affect pectin degradation and fruit softening. Changes in the pectin content and activity of cell wall polysaccharide-degrading enzymes (PE, exo-PG, endo-PG, and EG) during low-temperature storage (0 ℃ and 10 ℃) of “banbianhong” plum were investigated in this study. Correlation analysis was carried out to explore the effect of cell wall enzyme activity on pectin degradation. The results showed that the changes in the activities of four cell wall enzymes were different during low-temperature storage, indicating that lower temperatures inhibited enzyme activity to a certain extent. PE activity showed significant difference after 5 days storage under 0 ℃ and 10 ℃, while significant differences were found in exo-PG activity during the entire storage period. When the plum was stored at 0 ℃ and 10 ℃, activities of endo-PG and EG did not show significant difference during the first 10 days and the trend of changes in endo-PG activity was similar to that of EG, however, the peak value of endo-PG activity appeared later than that of EG. The results of correlation analysis between pectin content and cell wall enzyme activity showed that protopectin and SSP content showed a significant negative correlation with WSP content. The activity of PE exhibited a significant positive negative correlation with ASP and HSP content. Thus, PG played an important role in the conversion process from protopectin and SSP to WSP, while EG played a minor role on the degradation of pectin in plums.

辽宁省食品安全重点实验室开放课题（LNSAKF2011026）；辽宁省食品质量与安全优秀教学团队项目（SPCX12）