Abstract
BACKGROUND: Postharvest pepper fruits undergo quality deterioration including water loss, shrinkage and nutritional decline, which limits their commercial value. Notably, nano-silicon (SiNPs) improves postharvest vegetable quality, but its regulatory mechanism on pepper storage quality, especially metabolic changes, remains unclear. Therefore, this study explored SiNPs effects on P70 pepper phenotype, storage quality and metabolism to optimize postharvest preservation. RESULTS: SiNPs treatment significantly improved P70 pepper fruits storage quality. Under roomtemperature (RT) and low temperature (LT) storage conditions, SiNPs treatment (RT-NP, LT-NP) effectively alleviated shrinkage, water loss, and hardness decline. After 6 days of storage, LT-NP group had 1.09-fold higher hardness than LT group, while LT group weight loss was 1.46-fold that of LT-NP. For nutritional quality indicators, SiNPs treatment maintained higher contents of vitamin C, flavonoids, soluble solids and soluble sugar. In terms of antioxidant capacity, SiNPs treatment enhanced the activities of superoxide dismutase, peroxidase and catalase; LT-NP had 1.11-fold higher SOD at 6 days and 1.54-fold higher POD at 4 days than LT. Metabolomic analysis detected1041 metabolites, mainly including flavonoids (22.1%) and phenolic acids (13.7%). Compared with LT group, LT-NP had 164 up- and 79 down-regulated differential metabolites, enriched in flavonoid biosynthesis, starch-sucrose and amino acid metabolism. LT-NP up-regulated flavonoids (Galangin, Apigenin), D-Sucrose and activated polyamine biosynthesis. CONCLUSIONS: SiNPs improves P70 pepper postharvest quality by reducing water loss, maintaining hardness and nutrients. Collectively, the mechanism involves enhanced antioxidant enzyme activity and regulated key metabolites in flavonoid, sugar and amino acid pathways, supporting SiNPs application in pepper postharvest preservation.