Effects of 1–MCP Treatment on Postharvest Fruit of Five Pomegranate Varieties during Low-Temperature Storage

Abstract

Pomegranate fruit production and consumption are restricted by appropriate postharvest handling practices. 1–MCP (1–methylcyclopropene) is a natural preservative of fruits and vegetables; however, its effects on the storage of different pomegranate varieties have not been extensively investigated. Herein, the effects of 1.0 μL L−1 1–MCP on postharvest pomegranate fruit of three soft-seed ‘Mollar’, ‘Malisi’, and ‘Tunisan soft seed’ and two semi-soft-seed ‘Moyuruanzi’ and ‘Dongyan’ were investigated over 90 d (days) under low-temperature storage at 4 ± 0.5 °C with a relative humidity of 85–90%. Several indexes of exterior and interior quality were recorded, the sensory quality was evaluated, and the respiration and ethylene production were also determined. The results showed that peel browning was generally more severe in the soft-seed varieties than in the semi-soft-seed varieties. Significantly lighter peel browning presented in the three soft-seed fruits from 45 d after the 1–MCP treatment, with 35%, 19%, and 28% less than those controls at 90 d, correspondingly. However, 1–MCP only significantly decreased peel browning in the semi soft-seed fruits at 60 days. A prominent decrease in weight loss was recorded in all five varieties, with ‘Malisi’ showing the largest and ‘Dongyan’ the smallest difference between the 1–MCP and control treatments. Through the results of color, physiological, and chemical changes, as well as sensory properties, better color and total acceptance were found with higher titratable acids and vitamin C but with decreased anthocyanins in most fruits treated with 1–MCP. In contrast to the control, remarkable suppression of ethylene production peaks in all whole fruits and periodical increase in respiration rates in the soft-seed whole fruits were activated at 30–60 d after storage by the 1–MCP treatment, roughly when peel browning occurred and began increasing. Overall, our findings provided a crucial foundation for extending the application of 1–MCP in postharvest preservation of pomegranates.