Decontamination of Listeria innocua from fresh-cut broccoli using UV-C applied in water or peroxyacetic acid, and dry-pulsed light

Abstract

The efficacy of two irradiation technologies: Ultraviolet-C light (UV-C), applied in water or in diluted peroxyacetic acid, and dry-pulsed light (PL) for the inactivation and growth inhibition of Listeria innocua in fresh-cut broccoli were evaluated. Water-assisted UV-C (WUV) (0.3 and 0.5 kJ/m2) reduced L. innocua initial populations by 1.7 and 2.4 log10 CFU/g, respectively; the latter dose also inhibited their growth for 8 d at 5 °C. Replacing water with 40 or 80 mg/L peroxyacetic acid did not improve this efficacy. Pulsed light (5, 10, 15, and 20 kJ/m2) showed no effect on native microbiota. Neither did 15 kJ/m2 PL inactivate L. innocua or inhibit its growth. Nonetheless, 24-h post-processing, PL (15 kJ/m2) increased total phenolic content by 25% in respect of chlorine-sanitation, and enhanced total antioxidant capacity by 12 and 18% compared to water and chlorine controls, respectively. Unlike dry-PL, WUV appears to be a suitable technology for controlling L. monocytogenes populations in fresh-cut broccoli.

Industrial relevance The present work provides relevant information to the fresh-cut food industry regarding a suitable decontamination alternative to chlorine sanitation. Low-dose immersion-assisted UV-C allows inactivation and inhibition of native and pathogenic microbiota while generates non-toxic byproducts and allows reusing the process water thereby enabling savings in water consumption. The results obtained herein provide new tools to ensure both quality and safety of minimally processed products, contributing to the so-called “smart green growth” addressed to provide a more innovative and sustainable future for the food industry.