Electron-beam generated X-ray irradiation could retard the senescence of postharvest Hericium erinaceus via regulating reactive oxygen metabolism

Fresh Hericium erinaceus, a type of white mushroom, is prone to browning and microbial invasion after harvest due to high rate of metabolism. This study aimed to clarify how electron-beam generated X-ray (EBGX) irradiation (0, 1.0, 1.5, and 2.0 kGy) affects the senescence of postharvest fresh H. erinaceus during storage at 15 degrees C for 9 d. The effects of EBGX irradiation on biological properties of H. erinaceus were evaluated. Results indicated that EBGX irradiation reduced the incidence of browning in H. erinaceus, increased firmness, inhibited the respiration rate, lowered malondialdehyde (MDA) content and electrolyte leakage relative to untreated samples. Moreover, the natural microflora presents on H. erinaceus were prominently inhibited (P < 0.05) in 1.0 kGy compare to control group after storage, such as total bacterial count (35.6%), molds and yeasts (31.4%), and Pseudomonas (33.2%). Meanwhile, exposure to 1.0 kGy of irradiation treatment exhibited a minimum hydrogen peroxide content (51.2 nmol kg(-1)) and superoxide anion production rate (1.88 mu mol kg(-1) min(-1)) at 9 d, enhanced the activities of antioxidative enzymes (superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase), as well as declined oxidative stress by regulating the expression of related genes (HeSOD1, HeSOD2, HeCAT1, HeCAT2, HePOX1, and HePOX2).TUNEL analysis also observed that H. erinaceus treated with 1.0 kGy remarkably retained a lower nuclear DNA fragmentation. This finding suggests that the dose of 1.0 kGy EBGX irradiation could postpone the senescence process of fresh H. erinaceus and has the potential to be a promising physical preservation technology for fresh H. erinaceus.