Effect of application timing of deastringency and 1-methylcyclopropene treatments on fruit quality attributes and physiological disorders of two astringent persimmon cultivars during cold storage

Astringent persimmon (Diospyros kaki Thunb.) fruit are treated with high levels of CO2 or alcohol treatments to remove bitterness, but additional treatments are needed to maintain fruit firmness for long-term cold storage. Currently, 1-methylcyclopropene (1-MCP) is widely employed to maintain fruit firmness during cold storage. The objective of this study was to evaluate the effects of application timing of a combination of deastringency and 1-MCP treatments on fruit quality attributes and the incidence of physiological disorders in the cold-stored astringent persimmon fruit of two cultivars, ‘Tonewase’ and ‘Sangjudungsi’. Fresh weight loss gradually increased in ‘Tonewase’, regardless of the timing of the deastringency and 1-MCP treatment. However, the 1-MCP treatment alone resulted in the smallest loss of fresh weight compared with the other treatments in ‘Sangjudungsi’. Fruit firmness was highly maintained by the 1-MCP treatment, regardless of cultivar and application timing. Furthermore, the soluble solids content (SSC) was not affected by the 1-MCP treatment, but was significantly reduced by the deastringency treatment. The SSC was highly retained in ‘Sangjudungsi’. The variation in various color variables was greater in ‘Sangjudungsi’ fruit than in ‘Tonewase’ fruit. Compared with the other treatments, the combination of 1-MCP and deastringency treatments significantly reduced all color variables at both of the peel regions of ‘Tonewase’ fruit. Fruit softening, decay, and wilting rates were highest in the combined 1-MCP and deastringency treatments in ‘Tonewase’ fruit. On the other hand, ‘Sangjudungsi’ was relatively less susceptible to physiological disorders during cold storage. Overall, our results show that astringent persimmon cultivars require individually-tailored management techniques immediately before cold storage to retain fruit quality.