Impact of Combined Light and Modified Atmosphere Packaging on Postharvest Quality and Carbohydrate Fluctuations of Kyoho Grapes

Kyoho grapes are rich in nutrients, yet their susceptibility to spoilage poses a significant challenge for postharvest preservation. While light treatment can improve fruit quality and carbohydrate metabolism in postharvest grapes, the potential benefits of combining light treatment with modified atmosphere packaging (MAP) remain unexplored. A preservation method that combined red and blue light treatments with MAP has been developed to enhance postharvest fruit quality and carbohydrate metabolism in Kyoho grapes. Our study showed that this combined treatment significantly increased postharvest fruit hardness, as well as total soluble solids (TSS) and fruiting pedicel water content. It also improved the activities of superoxide dismutase (SOD) and phenylalanine ammonialyase (PAL) and increased the antioxidant, anti-browning capacity. This composite treatment slowed down sucrose decomposition by regulating the activities of key enzymes of carbohydrate metabolism (sucrose synthase (SS), sucrose phosphate synthase (SPS), neutral invertase (NI) and acid invertase (AI)). After 60 days of storage, the glucose, fructose, and sucrose contents of the RP group increased by 13.4%, 30.2%, and 18.1%, respectively, compared to the CK group (p < 0.05). In summary, light combined with modified atmosphere packaging significantly improved the physicochemical properties and sugar metabolism of postharvest grapes. The results indicated that the optimal treatment condition was continuous red-light irradiation combined with MAP. The hardness, TSS content, VC content and glucose content of Kyoho grapes in this treatment group were the best in all treatment groups.