Ethephon and 1-methylcyclopropene regulate storage quality and browning of fresh-cut Chinese water chestnuts

Abstract

The phytohormone ethylene responds positively to abiotic stress, but its effect on quality deterioration of fresh-cut Chinese water chestnuts (CWCs) caused by mechanical damage remains unclear. Here, the effects of single or combination treatments of ethephon (ET) and 1-methylcyclopropene (1-MCP) on fresh-cut CWCs during storage at 10 °C for 5 d were investigated. The results indicated that ET treatment was most effective in maintaining CWCs’ visual quality, followed by 1-MCP preceding ET treatment, 1-MCP treatment, and 1-MCP following ET treatment. Compared with 1-MCP treatment group, ET-treated fruit exhibited lower expressions of CwPAL, CwCHS1 and CwCHI1 and decreased activity of phenylalanine ammonia-lyase activity to inhibit flavonoid accumulation but higher catalase and superoxide dismutase and peroxidase (POD) activities and lower malonaldehyde content to maintain reactive oxygen species balance and suppress microbial growth. Nevertheless, ET treatment promoted fruit weight loss and CO2 concentration in the package, which was reversed by the preceding 1-MCP application rather than the subsequent 1-MCP treatment. 1-MCP followed by ET treatment not only inhibited the levels of flavonoid compounds and oxidation catalyzed by POD compared with the post-1-MCP treatment, but also reduced H2O2 production and microbial spoilage with a higher catalase activity. These results show that ET could maintain the quality of fresh-cut CWC by boosting antioxidant capacity, inhibiting microbial growth and suppressing enzymatic generation of browning substrates. In addition, compared with ET treatment, 1-MCP followed by ET treatment, despite showing weaker antioxidant enhancement, could inhibit the senescence of fresh-cut CWCs, suggesting its suitability for quality control of fresh-cut CWCs.