The preservation of Listeria-critical foods by a combination of endolysin and high hydrostatic pressure

Abstract

The aim of this work was to examine the combination of endolysin PlyP825 and high hydrostatic pressure (HHP) processing against a cocktail of stationary phase Listeria monocytogenes cells in several Listeria-critical food products (i.e. milk, mozzarella and smoked salmon). In order to determine the efficacy of the combined application, both challenge-lethality tests and storage tests were performed. In milk and mozzarella, we could demonstrate that the application of PlyP825 prior to HHP processing allowed for a synergistic inactivation of cells, a reduction in the pressure level with equal antimicrobial efficacy and an enhanced eradication of L. monocytogenes during storage at abuse temperatures. For smoked salmon, no such effects were detected. Although the efficacy of the method was highly dependent on the food vehicle and parameters applied, we hereby demonstrated the potential of the combined endolysin-HHP application for complete eradication of L. monocytogenes from foods at milder processing conditions.

Keywords: Bacteriophage lysin; Cell wall hydrolase; Enzymes; Foodborne pathogen; Synergy.