Abstract: To investigate the effects of ultraviolet light-emitting diode (UV-LED) and mercury lamp treatments on the postharvest physiological characteristics and storage quality of shiitake mushrooms (Lentinula edodes), fresh mushrooms were irradiated with either UV-LED (275 nm) or a mercury lamp at a dose of 4 kJ/m2 and then stored at 4 ℃. The dynamic changes in physicochemical indicators (color, mass loss rate), nutritional components (soluble protein, reducing sugar, free amino acids), bioactive compounds (total flavonoids, total phenols), enzyme activities (polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL)), and microbial and sensory qualities of shiitake mushrooms in each group were assessed on days 0, 3, 6, 9, 12, 15, 18, and 21. Two-way analysis of variance (two-way ANOVA) was employed to explore the effects of light source type, storage time, and their interaction on each quality indicator. The results showed that UV-LED treatment significantly enhanced PAL activity, efficiently activating the phenylpropanoid metabolic pathway and thereby increasing the contents of phenolic and flavonoid antioxidants (P < 0.05). This treatment also increased PPO and POD activities, enhancing antioxidant defense while limiting enzymatic browning to a low level. Furthermore, UV-LED treatment effectively maintained nutritional components such as free amino acids and reducing sugar, and significantly reduced mass loss rate (P < 0.05). In contrast, although mercury lamp treatment exhibited stronger instantaneous sterilization effects in the late storage period due to its wavelength advantage, it induced more severe browning and greater nutrient loss. Therefore, UV-LED treatment prior to cold storage can effectively improve the storage quality of fresh shiitake mushrooms, extending the shelf life to 21 days.

Key words: ultraviolet light-emitting diodes; low-pressure mercury lamp; shiitake mushroom; postharvest preservation; phenylpropanoid metabolism; two-way analysis of variance