Postharvest strawberry is susceptible to mechanical damage and fungal attack, which poses serious storage challenges. In this study, senescence of strawberry fruit was successfully delayed using 0.25, 0.5 and 1 g L- 1 alpha-lipoic acid (alpha-LA), and microbial proliferation was effectively inhibited during the storage. In particular, the treatment at with 0.5 g L- 1 alpha-LA was the most effective, significantly reducing the decay rate and weight loss, while sustaining the firmness, TSS content and color. Strawberry fruit treated with alpha-LA showed higher total phenolics, total flavonoids, total anthocyanin, ascorbic acid, and individual phenolic compounds content compared with the control. alpha-LA attenuated strawberry membrane lipid peroxidation by inhibiting MDA and H2O2 production, and increasing antioxidant capacity. Transcriptomic analysis revealed significant enrichment of genes related to phenylpropanoid biosynthesis, and the transcription factors FaMYC2 and FaMYB308 might act as negative regulators in phenolic metabolism. In addition, alpha-LA remarkably enhanced the expression of key genes related to phenolic metabolism and anthocyanin synthesis. In summary, alpha-LA maintained quality by modulating phenolic metabolism and antioxidant capacity in postharvest strawberry.

At present, fruits still undergo extensive decay and deterioration after harvesting. α-Lipoic acid (α-LA) is a natural, pollution-free, and low-cost preservative, which can effectively inhibit the senescence of postharvest fruits. To better utilize the preservation potential of α-LA, in this study, it was reacted with Cu-metal-organic framework (Cu-MOF) and loaded in large quantities onto the Cu-MOF, known as LA@Cu-MOF. On this basis, an antibacterial film with dual responsive release was prepared. The results indicated that LA@Cu-MOF exhibited a significant inhibitory effect on S. aureus, E. coli, and B. cinerea. Additionally, the release of α-LA in the film demonstrated superior response release in weakly acidic and high humidity environments. Moreover, the coating film could maintain the appearance and quality indicators of fruits for at least 6 days. Therefore, this method effectively extended the shelf life of fruits while maintaining their quality, making it a promising intelligent responsive fruits preservation material.

In this study, the molecular pathways of SlERF7 in regulating the synthesis and accumulation of phenolic compounds induced by postharvest UV-C in tomato fruit was deeply investigated by constructing transgenic plants. The findings revealed a pronounced induction of phenolic compounds accumulation following UV-C irradiation, coupled with heightened activities of PAL, 4CL, C4H, CHS, and CHI enzymes, alongside upregulated expression levels of SlPAL5, SlC4H, Sl4CL, SlCHS2, and SlCHI within SlERF7 overexpressed fruit. Conversely, SlERF7 knockout fruit exhibited diminished levels of phenolic compounds, enzyme activities, and gene expression after UV-C irradiation. Furthermore, subcellular localization analysis showed that SlERF7 was localized in the nucleus. Dual luciferase assay and electrophoretic mobility shift assay (EMSA) indicated that SlERF7 directly bound to the GCC-box in the SlPAL5 promoter and activated its transcriptional activity. Therefore, it was confirmed that SlERF7 might positively promote UV-C-induced phenolic biosynthesis in postharvest tomato fruit by targeting the promoter of SlPAL5.

Fresh-cut pear fruit is greatly impacted by enzymatic browning, and maintaining quality remains a challenge. This study examined the impact of exogenous α-lipoic acid (α-LA) treatment on enzymatic browning and nutritional quality of fresh-cut pears. Results revealed that 0.5 g/L α-LA treatment effectively maintained color and firmness, and inhibited the increase in microbial number. The α-LA treatment also reduced MDA and H2O2 contents, decreased PPO activity, and enhanced SOD, CAT, and PAL activities. The α-LA treatment notably upregulated phenolic metabolism-related gene expression, including PbPAL, Pb4CL, PbC4H, PbCHI and PbCHS, and then increasing total phenols and flavonoids contents. Furthermore, it also influenced carbohydrate metabolism-related gene expression, including PbSS, PbSPS, PbAI and PbNI, maintaining a high level of sucrose content. These findings indicated that α-LA treatment showed promise in reducing browning and enhancing fresh-cut pears quality, offering a potential postharvest method to prolong the lifespan and maintain nutritional quality.

The effects of postharvest melatonin treatment on antioxidant activity and gamma-aminobutyric acid (GABA) biosynthesis in yellow-flesh peach fruit stored at 4 degrees C and 90% RH for 28 d were explored. Results showed that melatonin treatment was effective in maintaining firmness, total soluble solids content and color in peach fruit. Melatonin treatment significantly reduced H2O2 and MDA contents, enhanced high level of non-enzymatic antioxidant system (ABTS center dot+ scavenging capacity), and increased the activity or content of antioxidant enzymes including CAT, POD, SOD and APX. Melatonin treatment increased the contents of total soluble protein and glutamate, while reducing total free amino acid content. Moreover, melatonin treatment up-regulated the expression of GABA biosynthesis genes (PpGAD1 and PpGAD4) and suppressed the expression of GABA degradation gene (PpGABA-T), resulting in the accumulation of endogenous GABA. These findings indicated that melatonin treatment exerted positive effects on improving antioxidant activity and promoting GABA biosynthesis in yellow-flesh peach fruit.

The role of melatonin treatment (0.01, 0.1, 1 and 10 mmol L -1 ) in affecting postharvest quality, phenolic and melatonin accumulation in yellow-flesh peach fruit stored at 4 o C and 90% RH for 28 d were assessed. The results indicated that the postharvest quality of peach fruit treated with 0.1 mmol L -1 melatonin remained the best, which was exhibited in reducing weight loss, postponing color change, maintaining fruit firmness and TSS content, and increasing ascorbic acid level. Besides, 0.1 mmol L -1 melatonin treatment notably increased the contents of total phenolics and flavonoid, and up-regulated the expression of phenolic biosynthesis related genes including PpPAL , PpC4H and Pp4CL . In addition, melatonin treatment increased the enzymes activities in melatonin biosynthesis including TDC, T5H, SNAT and ASMT, and consequently accelerated the accumulation of endogenous melatonin. These results manifested that melatonin treatment may be a promising method to maintain quality and prolong postharvest life in peach fruit.