Peach fruit faces severe postharvest losses due to thin epidermis and susceptibility to Rhizopus stolonifer-induced soft rot. Chemical control risks residue and resistance issues, demanding eco-friendly alternatives. This study elucidated the mechanism by which trans-2-hexenal (E2H) mitigated postharvest soft rot caused by Rhizopus stolonifer in peach (Prunus persica cv. Hujing Milu) fruit. The results demonstrated that E2H treatment significantly delayed lesion expansion by 44.7% and disease incidence by 23.9% while effectively maintaining fruit quality by delaying firmness loss, reducing juice leakage, and suppressing malondialdehyde (MDA) accumulation. E2H treatment upregulated phenylpropanoid pathway gene expression, enhancing key phenylpropanoid metabolism enzymes activities (phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), polyphenol oxidase (PPO), peroxidase (POD)), leading to the increase of total phenolics by 7.9%. E2H treatment analysis revealed significant enhancements in both chitinolytic activity (CHI) and β-1,3-glucanase (GLU) activity by 85.7% and 12.9%, indicating potentiation of the enzymatic defense system. Concurrently, E2H treatment could improve the redox modulation capacity of peach fruits through promoting catalytic efficiency of redox-regulating enzymes, increasing the accumulation of ascorbic acid (AsA) by 8.1%, inhibiting the synthesis of dehydroascorbic acid (DHA) by 18.6%, as well as suppressing the biosynthesis of reactive oxygen species (ROS). These coordinated enhancements in pathogenesis-related proteins (CHI, GLU), phenylpropanoid metabolism activation, and antioxidant systems are strongly associated with E2H-induced resistance against Rhizopus stolonifer, though contributions from other factors may also be involved.

Vegetable soybean is a major crop in China with significant economic value. However, it is prone to yellowing and browning during postharvest storage, which reduces quality, marketability, and competitiveness. ‘Tongdou No. 6’ was used to evaluate postharvest quality preservation through combined cold shock treatment and nanocomposite polymer packaging. The results demonstrate that the combined treatment effectively slows the green-to-yellow color change by significantly reducing chroma a* value, weight loss, and chlorophyll degradation. Additionally, it markedly reduces the accumulation of malondialdehyde (MDA) and reactive oxygen species (H₂O₂ and O₂·⁻), while decreasing the activities of polyphenol oxidase (PPO) and peroxidase (POD). The treatment also significantly enhanced the levels of antioxidant compounds, including ascorbic acid (AsA), total phenolics, and total flavonoids, and boosted the activities of key antioxidant enzymes—ascorbate peroxidase (APX), superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL), and catalase (CAT). Moreover, the combined application of cold shock and nanocomposite polymer packaging significantly enhanced the scavenging capacity against DPPH and hydroxyl (OH⁻) radicals. Overall, combining these two techniques effectively delayed senescence-related discoloration by activating the antioxidant system, regulating ROS metabolism, and reducing oxidative damage. This approach is highly effective in maintaining postharvest quality and offers a promising solution to the storage-induced deterioration of vegetable soybeans.

Peach fruit develops chilling injury (CI) during cold storage, yet the symptoms are milder at 0 °C than at 5 °C; however, the underlying mechanism remains unclear. This study demonstrated that peach fruit stored at 0 °C maintains higher levels of structural phospholipids and membrane lipid unsaturation, along with lower activities of lipase and lipoxygenase (LOX), thereby alleviating membrane damage. Using lipidomics, we identified phosphatidic acid (PA) as a lipid closely associated with CI characteristics and revealed that it plays a signaling role at the early stage of storage at 0 °C, while its reduced levels at the later stage alleviate membrane damage, thereby participating in the regulation of CI in peach fruit. Moreover, at 0 °C, Phospholipase D (PLD) activity exhibited an initial increase followed by a decrease, which was consistent with the overall changes in PA content. During storage, PLD activity and PA content at 0 °C were significantly lower than those at 5 °C and 15 °C. These findings highlight the critical role of PA in temperature-dependent regulation and provide potential molecular targets for precise management of CI in the postharvest cold chain of peach fruit.