Trans-2-hexenal treatment maintains postharvest wax apple quality by alleviating oxidative damage, activating the phenylpropanoid pathway and suppressing cell wall degradation

Wax apple is thin and juicy and prone to postharvest quality deterioration, including softening, shrinkage, peel fading, and decay. Trans-2-hexenal (E2H) has emerged as a highly effective natural preservative for fruits and vegetables in recent years. In this study, the optimal concentration of E2H was determined to be 0.5 μL L −1 , and the fruit was fumigated at 20 °C for 24 h and stored at 20 °C for 12 days to explore its effect on storage quality. Further mechanistic analysis revealed that E2H treatment increased the scavenging ability of reactive oxygen species (ROS) by upregulating the activities of the antioxidant system, with superoxide dismutase (SOD) and catalase (CAT) activities in treated fruit being 1.72 and 1.15 times higher than the control on day 9 of storage, respectively. Simultaneously, it activated key enzymes in the phenylpropanoid pathway, promoting the accumulation of total phenolics, thus enhancing the antioxidant and disease-resistant defense ability of fruits. Furthermore, E2H significantly inhibited the activities of cell wall-degrading enzymes, delayed the degradation of pectin, cellulose and hemicellulose, maintained the metabolic balance of pectin components, protected the cell wall structure, and effectively slowed down the postharvest softening process of fruits. In summary, E2H treatment maintains the storage quality of wax apple fruit and inhibits decay by regulating antioxidant activity, phenylpropanoid metabolism, and cell wall degradation pathways, demonstrating promising application prospects in the field of postharvest preservation.