Effects of CO2 on the resuscitation of Listeria monocytogenes injured by various bactericidal treatments

To assure the microbiological safety and quality of a food product, a combination of preservation hurdles is often used. Therefore, the effects of carbon dioxide at concentrations of 0, 20, 40 and 60% in modified atmospheres on the resuscitation of Listeria monocytogenes cells injured by mild bactericidal treatments during storage at 7 °C were examined. The bactericidal treatments were intense light pulses (ILP), chlorine dioxide (ClO2), lactic acid (LA) and heat. The results indicated additional bactericidal effects of CO2 on cultures treated with LA, ClO2 and ILP, with additional reductions in viable L. monocytogenes of 0.5–1.0 log cfu/ml. Lag phase duration was significantly different between the different treatments, with non-treated cells having the shortest lag phase, followed by that of heat, intense light pulses, lactic acid and finally ClO2 treated cells. Maximum growth rate was also estimated and results showed a negative correlation with increasing CO2 concentrations. A relationship was found between the amount of sub-lethally damaged cells after a mild inactivation treatment and the lag phase duration in the CO2 environment. Current findings demonstrate the possibility that combining mild decontamination treatments and packaging in a CO2 enriched environment could reduce the risk of L. monocytogenes infections in food due to an extension of the lag phase.