Abstract: In this study, we evaluated the effects of high CO2 exposure (at 3% for 48 h) followed by electron beam irradiation (EBI) (2 kGy) on the quality of fresh-cut apples and analyzed the underlying mechanism. Results showed that EBI accelerated tissue damage and nutrient loss despite sterilizing apples. Compared with EBI, the combined treatment significantly increased the hardness (35.1%) and crispness (31.8%) on day 10 of storage, inhibited browning, reduced ascorbic acid loss by 72.1%, and enhanced the scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical cation. Flavor analysis showed that the combined treatment effectively retained the characteristic esters such as ethyl butyrate and hexyl acetate, and inhibited the generation of undesirable flavor substances such as hexanal. Mechanistic studies indicated that the combined treatment exerted its effects through two pathways: it inhibited the activity of polyphenol oxidase and peroxidase (reducing their peak levels by 53.6% and 28.4%, respectively), activated phenylalanine ammonia-lyase activity (increasing it by 38.0%), and significantly increased the activity of antioxidant enzyme systems including glutathione reductase, catalase, and superoxide dismutase (by 1.2–1.7 times). Additionally, it inhibited malondialdehyde accumulation by 30.2% and the increase in relative conductivity by 26.7%. It also significantly reduced the rate of superoxide anion radical production and H2O2 content by 28.5% and 29.3%, respectively, thereby reducing oxidative damage and maintaining cell membrane integrity. In conclusion, the combined treatment mitigated oxidative damage to cells caused by EBI, thereby enhancing the quality of fresh-cut apples. The findings of this study provide a technical reference for the application of stress induction combined with physical cold sterilization in the processing of fresh-cut fruits and vegetables.

Key words: apple; fresh-cut; stress; antioxidant; electron beam; irradiation