Abstract: In this study, Oudemansiella raphanipes was irradiated postharvest with different doses (0, 0.5, 1.0 and 1.5 kGy) of γ-rays, and stored at (4.0 ± 0.5) ℃ and (80 ± 5)% relative humidity for 8 d. The aim was to investigate the effect of irradiation treatment on the postharvest storage quality, respiration and energy metabolism of the mushroom. The results demonstrated that the 0.5 and 1.0 kGy treatments delayed the quality deterioration of O. raphanipes, with this effect being more pronounced at 0.5 kGy. Physiological and biochemical analyses showed that the 0.5 kGy irradiation treatment effectively maintained the postharvest sensory quality of O. raphanipes, inhibited the increase in mass loss rate, delayed the rise in respiration rate, and reduced nutrient losses. Moreover, the treatment suppressed the activities of respiratory metabolism-related enzymes, such as phosphoglucose isomerase (PGI), pyruvate kinase (PK), succinate dehydrogenase (SDH), and cytochrome c oxidase (CCO), but enhanced H+-ATPase and Ca2+-ATPase activities. Concurrently, it reduced the contents of nicotinamide adenine dinucleotide (NAD) and reduced nicotinamide adenine dinucleotide (NADH), slowed down the accumulation of AMP, and maintained high ATP and ADP contents and energy charge levels, thereby altering cellular energy metabolism. These findings suggest that the 0.5 kGy γ-ray irradiation treatment could reduce the respiration rate and delay the substrate consumption by inhibiting the glycolysis-tricarboxylic acid cycle (EMP-TCA) and electron transport chain (ETC) transporter efficiency, and at the same time maintain a higher energy level, thereby delaying the quality deterioration of O. raphanipe during postharvest storage.

Key words: γ-rays; Oudemansiella raphanipes; storage; respiratory metabolism; energy metabolism