Hot water treatment alleviates peel browning in oriental melons through cutin biosynthesis: A comprehensive metabolomics approach

Abstract

Peel browning is a significant postharvest issue that affects the marketability of oriental melons. This study aimed to investigate the impact of hot water (HW) treatment on peel browning and metabolites in oriental melons during cold storage and retail conditions. The results revealed that HW treatment effectively reduced the browning index and upregulated the gene expression of heat shock proteins (HSPs) and lipoxygenase, known to play crucial roles in stress responses under chilled condition and browning. Additionally, HW treatment induced the expression of cuticle-related genes, CERs and LACS, particularly under retail conditions at 20 °C after cold storage, resulting in a thicker cuticle layer in treated fruits compared to non-treated fruits. Metabolomics analysis demonstrated significant impacts of HW treatment on linoleic acid metabolism, cutin, and suberin biosynthesis pathways. Specifically, HW treatment led to a notable increase in the concentration of cutin in HWT45-treated fruits, with a 27% increase at 14 days and a remarkable 54% increase at 14 + 2 days compared to the control group. These findings highlight the association between peel browning in oriental melons and cutin/suberin biosynthesis. HW treatment induces the formation of cutin metabolites, leading to enhanced cuticle deposition and reduced browning. These insights provide a basis for developing effective postharvest treatments to prolong the shelf life and enhance the marketability of oriental melons.