Kiwi is a nutrient-rich fruit, one of the few varieties that remain bright green after ripening, with this green color coming from chlorophyll (Chl). During the storage of kiwi, Chl is quite unstable and easily degrades, leading to discoloration, which is accompanied by the ripening and senescence of the kiwi fruit. Therefore, it is particularly important to delay the degradation of Chl during storage.
Researchers from Northwest A&F University, including Song Xiaoqing, Ren Yamei, and Zhang Yanyi, studied the effects of 1-Methylcyclopropene (1-MCP) treatment on the chlorophyll derivatives and related enzyme activities of kiwi fruit during cold storage using the “Qinmei” kiwi as test material, deriving the mechanism of chlorophyll degradation in kiwi fruit, providing a theoretical basis for the preservation of green color and protection technology during storage.
With the extension of storage time, the contents of chlorophyll a (Chl a) in both the control and 1-MCP treated fruits showed a trend of decrease – increase – decrease. In the later storage period, 1-MCP can inhibit the reduction of Chl a, chlorophyll b (Chl b), and total chlorophyll (T Chl), delaying the aging of the fruit. Throughout the storage period, the content of carotenoids (Car) in kiwi fruit flesh was relatively low and showed little variation (P＞0.05), and there was no significant difference between the control and 1-MCP treated fruits (P＞0.05). 1-MCP treatment can inhibit the degradation of Chl a, Chl b, and T Chl.
Throughout the storage period, POD activity showed a trend of first increasing and then decreasing. 1-MCP treatment can enhance the POD activity in kiwi fruit, delaying the degradation and aging of Chl.
During the entire storage period, the Chlase activity of the 1-MCP treated fruit showed little variation and was consistently lower than that of the control fruit, with significant differences on the 45th day of storage (P＜0.05). From 0～15 d, both control and 1-MCP treated fruits showed a rapid increase in MDCase activity, peaking on the 15th day of storage, and then gradually decreasing. Compared to the control fruit, the MDCase activity of the 1-MCP treated fruit was consistently lower, with significant differences on the 45th and 60th days of storage (P＜0.05), indicating that 1-MCP treatment can inhibit the activity of both Chlase and MDCase to some extent, delaying the degradation of Chl and thus slowing the aging of the fruit.
During storage, the contents of dephytol chlorophyll a, magnesium-dechelated chlorophyll a, and magnesium-dechelated chlorophyll a in the control fruit generally showed a trend of first increasing and then decreasing. Throughout the storage period, the changes in dephytol chlorophyll a content in the 1-MCP treated fruit were minimal and consistently lower than that of the control fruit, with significant differences on the 30th day (P＜0.05). From 0～15 d, the content of magnesium-dechelated chlorophyll a in the control fruit rapidly increased and then quickly decreased. Throughout the storage period, the content of magnesium-dechelated chlorophyll a in the 1-MCP treated fruit was consistently lower than that of the control, with significant differences on the 15th day (P＜0.05). From 0～30 d, the content of magnesium-dechelated chlorophyll a in the control fruit gradually increased, and with the extension of storage time, its content rapidly decreased, while the content of magnesium-dechelated chlorophyll a in the 1-MCP treated fruit was consistently lower than that of the control, with significant differences on the 30th day (P＜0.05). In summary, 1-MCP can delay the degradation of chlorophyll and inhibit the production of chlorophyll derivatives.
Conclusion
Throughout the storage period, the trends of changes in Chlase and MDCase activities in the control fruit were consistent with the changes in the contents of dephytol chlorophyll a and magnesium-dechelated chlorophyll a, indicating that both enzymes participate in the degradation of kiwi Chl. The degradation process of Chl during kiwi storage follows the PAO pathway. Meanwhile, 1-MCP can inhibit the production of dephytol chlorophyll a, magnesium-dechelated chlorophyll a, and magnesium-dechelated chlorophyll a, indicating that 1-MCP can delay the degradation of chlorophyll.
1.0 μL/L 1-MCP treatment can enhance the POD activity in kiwi fruit, inhibit the activities of Chlase and MDCase, slow down the degradation of Chl, and inhibit the production of dephytol chlorophyll a, magnesium-dechelated chlorophyll a, and magnesium-dechelated chlorophyll a, thereby delaying the degradation of fruit greenness and the ripening and senescence of the fruit.
Source
This article “Post-Harvest Degradation Mechanism of Kiwi Chlorophyll and Effects of 1-MCP Treatment on Its Metabolism” is sourced from “Food Science” 2017, Volume 38, Issue 17, Pages 260-265, Authors: Song Xiaoqing, Ren Yamei, Zhang Yanyi, Shi Junling, Fan Mingtao. DOI:10.7506/spkx1002-6630-201717042. Click below to read the original text for related information.
Edited by: Food Science Correspondent Yuan Yuan, College of Life Sciences, Jiangxi Normal University, Yao Lake Campus Editor: Zhang Ruimei
