Abstract: Kiwifruits (Actinidia deliciosa cv. Qinmei) were treated at harvest with 1-methylcyclopropene (1-MCP) and then stored at (0.0 ± 0.5) ℃. The mechanism of chlorophyll degradation and the effect of 1-MCP treatment on the contents of chlorophyll and its derivatives and the activities of related enzymes were studied. The results showed that chlorophyllide a, pheophorbide a and pheophytin a were the major degradation products of chlorophyll a during storage. The contents of these three derivatives increased initially and then decreased during storage. The changes in the contents of chlorophyllide a and pheophorbide a were in accordance with the changes in the activities of chlorophylase and Mg-dechelatase, respectively. Therefore, chlorophyll degradation followed the degradation pathway of pheophorbide a oxygenase. The treatment with 1.0 μL/L 1-MCP increased the activity of peroxidase and delayed the maturity and senescence of kiwifruits. 1-MCP inhibited the activities of chlorophylase and Mg-dechelatase, and slowed down the degradation of chlorophyll. 1-MCP restrained the production of chlorophyllide a, pheophytin a and pheophorbide a, and thus delayed the maturity and senescence of kiwifruits. These results provide a theoretical basis for the application of 1-MCP to delay chlorophyll degradation in kiwifruit.

Key words: kiwifruit, chlorophylase, Mg-dechelatase, 1-methylcyclopropene (1-MCP), chlorophyll a derivatives