Application of enterocin-whey films to reduce Listeria monocytogenes contamination on ripened cheese

Abstract

An enterocin whey solution, obtained by growing Enterococcus faecalis L2B21K3 and L3A21K6 in sweet whey enterocin whey solution (EWS), was incorporated into gelatin/glycerol films that were tested for the control of Listeria monocytogenes. The films containing enterocins produced by either strain (EWS L2 and EWS K6 films) were shown to serve as a suitable matrix for bacteriocin release, preserve the anti-listerial activity for up to 90 days. When applied in cheese, EWS L2 and EWS K6 films were able to reduce L. monocytogenes contamination to undetected levels after 20 or 30 days, respectively, and prevented the migration of this pathogen from the films to cheese. The incorporation of EWS into films did not affect (p < 0.05) moisture content, solubility, permeability (water vapor and limonene), and elongation at break compared to control films (without EWS). However, thickness, swelling index and tensile strength were higher (p < 0.05) in EWS films. These results suggest that active EWS gelatin/glycerol films could be an effective, and safe application to control L. monocytogenes in cheese. In addition, the use of cheese whey as a culture medium for the production of the bacteriocins complemented with the incorporation in films formulation as a packaging material represents an alternative approach to reuse this by-product of cheese production.