The Effects of UV-C Irradiation and Low Temperature Treatment on Microbial Growth and Oxidative Damage in Fresh-Cut Bitter Gourd (Momordica charantia L.)

Abstract

Fresh-cut fruits and vegetables are convenient and retain maximum nutrients. However, even minimal processing accelerates product deterioration and reduces food safety due to microbial infection. In this study, the effects of UV-C irradiation, low temperature treatment, and their combination on the microbial risk of fresh-cut bitter gourd were evaluated. Firstly, next-generation sequencing technology was utilized to identify microorganisms on the surface of fresh-cut bitter gourd after 12 h of exposure to room temperature, and a total of 34 bacterial species were identified. Subsequently, fresh-cut bitter gourd treated with UV-C or/and 4 °C and then kept at room temperature for 6 h was assessed for its viable bacterial count. The results showed that both 0.5 and 1.5 kJ·m−2 UV-C irradiation significantly inhibited microbial growth compared to 4 °C and the no treatment control. Meanwhile, no significant differences were observed between UV-C and the combined treatments. Lower doses of UV-C irradiation reduced hydrogen peroxide and malondialdehyde content, increased the proline level, and improved the activities of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, catalase, and critical enzymes involved in the phenylpropanoid pathway, such as phenylalanine ammonia-lyase and polyphenol oxidase. This suggests that UV-C irradiation alone can effectively reduce bacterial contamination in fresh-cut bitter gourd to an acceptable level.