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.

This work has been supported by the CERCA Programme / Generalitat de Catalunya, the Secretaria d'Universitats i Recerca / Departament d'Economia i Coneixement / Generalitat de Catalunya, and the European Social Fund (grant FI-DGR-2015-0004); the University of Lleida (Ref.127/2016); the Spanish Ministry of Economy, Industry, and Competitiveness (grant FJCI-2016-29541); and the European Social Fund (grant RYC-2016-19949).The authors thank INRA (UMR SQPOV, Avignon), in particular Veronique Broussole and Fréderic Carlin, for providing access to the facilities. Thanks are also given to CLARANOR s.a. for allowing the use of the PL equipment, and in particular to Alain Berberian, for his technical assistance.