COMPARING THE QUASI-CHEMICAL AND OTHER MODELS FOR THE HIGH PRESSURE PROCESSING INACTIVATION OF LISTERIA MONOCYTOGENES

This paper presents the results of experiments designed to compare the ability of three different models in evaluating the inactivation kinetics of baro-resistant Listeria monocytogenes OSY-8578 using High Pressure Processing. Inoculated samples of whey protein were subjected to various high pressure treatments at temperature T = 40 °C to collect inactivation data that showed linear or non-linear kinetics (“shoulders” and “tailing”). The data were analyzed by three different kinetics models: (i) the Quasi-chemical model with four parameters, (ii) the two-parameter Weibull model, and (iii) the polynomial in the logarithm (“Polylog”) model. Rather than delving into the detailed qualitative aspects of the inactivation kinetics, we focus our approach here exclusively on one important inactivation parameter, the process¬ing time (tp), which is the time estimated to reduce the organism concentrations by a factor of 10⁶ at the high pressure conditions tested. A secondary model relating tp and high pressure is also obtained.