Synergistic effect of high pressure processing and pediococcus acidilactici in inactivation of Listeria innocua in ready-to-eat sausages

Abstract

Following consumers’ demand for safe and nutritious foods without chemical preservatives, food industries are looking for new preservation solutions. Among these, high pressure processing (HPP) and biopreservation are non-thermal technologies showing significant potential for effective food preservation without altering nutritional value and organoleptic properties of food. It has been shown that biopreservation using lactic acid bacteria (LAB) and/or their bacteriocins inhibit pathogens, but at present time there were no studies about the influence of HPP on the antimicrobial activity of LAB. The objectives of this study were to evaluate the effects of HPP on the antimicrobial activity of a bacteriocinogenic strain of LAB (Pediococcus acidilactici HA-6111-2) and its bacteriocin and to evaluate the effectiveness of HPP combined with P. acidilactici for inactivation of Listeria innocua N27 (used as a surrogate for Listeria monocytogenes) in RTE sliced meat sausages. Pediococcus acidilactici was exposed to pressures between 200 and 500 MPa at 25 °C for 5 min and subsequent freezing at -20 °C. A pressure of 200 MPa did not affect bacteriocin production, whereas 300 MPa caused a two times reduction in antimicrobial activity of P. acidilactici. Further increase of pressures (400 MPa and 500 MPa) reduced bacteriocin activity 4 to 8 times. High hydrostatic pressures and freezing postponed bacteriocin production. Bacteriocin production began 9 h earlier when the samples were not frozen. The antimicrobial activity of bacteriocins produced by P. acidilactici was reduced after pressurization. The synergistic effect of high hydrostatic pressure (300 MPa, 5 min, 25 °C) combined with P. acidilactici against L. innocua in ready to eat sliced meat sausages during storage at 4 °C for 60 days was assessed. Application of pressure and P. acidilactici resulted in 2 log inactivation of L. innocua. The food matrix had a protective effect on pressure inactivation of L. innocua. The results of this work clearly illustrate the potential of pressure combined with bacteriocinogenic cultures as an alternative for chemical preservation. Yet, synergistic effect of high pressure processing and P. acidilactici requires further investigation on more suitable foods.

Date of Award	2014
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Sónia Marília de Almeida e Castro (Supervisor)