Synergistic Effects of Short‐Term UV ‐C Exposure Combined With Low‐Dose Nisin Against Listeria innocua : Enhancing Microbial Safety While Preserving Quality Attributes in Minimally Processed Vegetable Salad

This study aimed to evaluate the effects of UV‐C light intensity and exposure time on quality indicators of a minimally processed vegetable salad (50% purple lettuce, 25% arugula, and 25% beet leaves) as well as to assess the effectiveness of its combination with nisin in enhancing microbial safety against Listeria innocua . Preliminary assays established maximum irradiation times to preserve total polyphenols and ascorbic acid: 90 s for low intensity (L‐I: 0.036 kJ/s·m 2 ) and 60 s for high intensity (H‐I: 0.070 kJ/s·m 2 ). While individual UV‐C treatments (up to 10 s) resulted in reductions of 0.5–1.0 log cycles, the combination with nisin (250–500 IU/g) led to enhanced microbial inactivation, with immediate reductions exceeding 5 log cycles in all cases. Notably, the application of a low nisin dose (125 IU/g) followed by UV‐C (0.3 kJ/m 2 ) demonstrated a superior bacteriostatic effect over 6 days under high‐contamination scenarios. Under more realistic contamination levels (10 5 CFU/g), this combination maintained undetectable Listeria counts for 7 days, complying with European food safety standards. These results demonstrate a synergistic hurdle effect, providing a practical and scalable approach to enhance the microbial safety and quality of ready‐to‐eat vegetable products.