浸钙对猕猴桃果实硬度变化影响的生化机制

猕猴桃果实在贮藏过程中硬度下降分为两个明显的阶段，第一阶段硬度下降较快，主要与淀粉的快速水解有关，由于采后浸钙不能有效地降低淀粉酶的活性，因而钙处理对第一阶段硬度下降的影响不大。第二阶段的硬度下降主要与果胶物质的水解有关，钙处理后的果实，多聚半乳糖醛酸酶（ＰＧ）的活性降低，非水溶性果胶物质的降解及水溶性果胶物质的上升速度变慢，从而有效地减缓了果实的软化速度。钙处理对猕猴桃果实的ＡＣＣ氧化酶及纤维素酶的活性没有明显的影响。

Biochemical Mechanism of the Firmness Changes of kiwifruit Treated by CaCl_2

Firmness of kiwifruit and the relative enzyme activities by the treatment of 5?Cl2 after harvest were studied.The results showed that the decrease of fruit firmness during storage included two phases. The first one was the rapid softening phase, while in the second phase slow loss of fruit firmness occurred.There was not much effect on the firmness of the first phase by the treatment of 5?Cl2, but it could reduce the softening rate obviously at the second phase,thus prolonging storage periods. The activity of polygalacturonase in kiwifruit was decreased after the fruits were treated with CaCl2, the degradation of protopectin and the increasing of water soluble pectin were declined, thus making the kiwifruit more firm than the control ones. But there was not much effect on the activities of ACC oxidase, amylase and cellulase by the treatment of 5% CaCl2.