Effects of 1-MCP on soluble tannins, total phenols, DPPH antioxidant scavenging, and vitamin C of Lanxi persimmon after removal of astringency

Persimmon (Diospyros kaki L.) is a fruit with high nutritional value and possesses medicinal effects on relieving oral ulcers, coughs, hypertension, etc. Lanxi persimmon is a typical completely astringent persimmon cultivar in China native to Lanxi City of Zhejiang Province. This study investigated the effects of 1-Methylcyclopropene (1-MCP) treatment on fruit quality maintenance of ‘Lanxi’ persimmon fruit during different storage at 0°C, 8°C, and 15°C by two deastringency methods. The contents of vitamin C (Vc), total phenols, tannins, and DPPH radical scavenging activity of persimmon fruits were periodically determined to evaluate storage quality. The results indicated that the two deastringency methods exhibited similar effects on the reduction of soluble tannin content. After deastringent treatment, the total phenol content of persimmon treated by 1-MCP was significantly higher than that of the control persimmon on the 28th day of storage at 15°C, 8°C, and 0°C, and the DPPH scavenging capacity with 1-MCP treatment stored at 0°C and 8°C on the 28th day of storage was markedly enhanced compared with that of the control. 1-MCP treatment inhibited the conversion of soluble tannins to insoluble tannins and the decrease of Vc content. However, the application of 1-MCP in the deastringent treatment failed to delay the reduction of Vc content, and the significant reduction of soluble tannin content was only observed on the 7th day of storage at 0°C by ethanol deastringency, and on the 14th day at 0°C, 7th day at 8°C, and 7th-28th days at 15°C by carbon dioxide deastringency. In conclusion, 1-MCP treatment effectively improved the content of total phenol and the DPPH scavenging capacity in the two deastringent treatments, and inhibited the decrease of soluble tannin at 15°C by carbon dioxide deastringency in Lanxi persimmon. This study clarifies the optimal application conditions of 1-MCP combined with different deastringency methods for Lanxi persimmon under multi-temperature storage, providing reliable technical reference and theoretical basis for the postharvest quality preservation, storage, and commercial promotion of local astringent persimmons.