猕猴桃果实软化衰老机理初探

目的]探讨猕猴桃果实软化衰老的机理。方法]用1%、3%Ca(NO3)2处理丰悦和金魁,测定猕猴桃软化衰老过程中淀粉酶、纤维素酶、PG酶活性及果胶和淀粉的含量。结果]丰悦采后60 d淀粉酶活性达到峰值,金魁采后40 d达到峰值,为4.57/mg FW,但均低于清水对照。两品种采后50 d PG酶活性达到峰值,纤维素酶活性20 d达到峰值,均低于对照。对照果实的水溶性果胶在开始阶段上升速度大于钙处理的,钙处理的金魁水溶性果胶含量在80 d时低于丰悦,表明丰悦果实软化速度大于金魁。两品种钙处理的猕猴桃果实淀粉含量高于对照。结论]淀粉和原果胶的降解是猕猴桃果实软化衰老的主要原因。钙处理能降低猕猴桃果实淀粉酶和纤维素酶活性,降低PG酶活性的峰值,有效减缓淀粉降解,延缓猕猴桃软化衰老。

Primary Exploration on the Softening Con,senescence Mechanism of Kiwifruit Fruit

Objective] The study aimed to explore the softening consenescence mechanism of kiwifruit fruit.Method] Kiwifruit varieties Fengyue and Jinkui were treated with 1% and 3% Ca(NO3)2 and the amylase,cellulase,PG enzyme activities and pectins and starch contents in the softening consenescence course of kiwifruit were determined.Result] The amylase activity in Fengyue reached peak value on the 60th d after harvest and that in Jinkui reached peak value on the 40th d after harvest,being 4.57 U/mg(FW),but they were all lower than that of CK(clear water).The PG enzyme activities in two varieties reached peak value on the 50th d after harvest and cellulase acticity reached peak value on the 20th d after harvest,both them were lower than CK.Water soluble pectins content in the contrast fruit increased faster than that in calcium treatment during the beginning stage.The water soluble pectins content in Jinkui in calcium treatment was lower than that in Fengyue on the 80th day,showing that the softening speed of Fengyue fruit was bigger than that of Jinkui.The starch contents in fruits of 2 kiwifruit varieties in calcium treatment were higher than that in CK.Conclusion] The starch and original pectins degradations were the main reason for the softening consenescence of kiwifruit fruit.Calcium treatment could reduce amylase and cellulase activities in kiwifruit fruit,decrease peak value of PG enzyme activity and slow starch degradation effectively and delay the softening consenescence of kiwifruit fruit.