Modeling the combined effect of high hydrostatic pressure and mild heat on the sub‐lethal injury of Listeria monocytogenes by Box–Behnken design

Abstract

AbstractIn this study, a predictive model based on the Box–Behnken design of response surface methodology was applied to investigate the effects of high hydrostatic pressure (300, 400 and 500 MPa), temperature (20, 30 and 40°C) and treatment time (5, 10 and 15 min) on the sub‐lethal injury of Listeria monocytogenes (L. monocytogenes). The percentage of sub‐lethal injury was calculated by the difference in L. monocytogenes counts observed on nonselective and selective media. The established predictive model presented a goodness of fit to the experimental data (p < .001) with high correlation coefficient value (R2 = .9999) and adjusted correlation coefficient value (Adj‐R2 = .9995), along with an insignificant lack‐of‐fit term (p = .4299). The synergistic effects of pressure, temperature and treatment time on the sub‐lethal injury of L. monocytogenes were found within the tested experimental ranges. Results indicated that the established model has the potential for predicting the effects of high hydrostatic pressure processing on the sub‐lethal injury of L. monocytogenes.Practical ApplicationsHigh hydrostatic pressure (HHP) processing has been an attractive way to replace conventional heat treatments to inactivate microorganisms for the preservation of foods. However, HHP processing can cause microorganisms to enter sub‐lethal injury state which pose a threat to food safety. There is a great need of quantification of injured population of L. monocytogenes in a wide range of pressure and temperature conditions. In this study, the changes of sub‐lethal injury of L. monocytogenes are described, which can be used to assess the HHP treatment efficacy and the synergistic action in food sterilization processes. The modeling for the sub‐lethal injury of L. monocytogenes cells induced by HHP processing combined mild heat was established. The effects of HHP processing on the sub‐lethal injury of L. monocytogenes could be understood further by this modeling which was helpful to facilitate industrial adoption of this technology. Based on these data, there was a reference for us to select appropriate processing parameters to avoid appearance of sub‐lethal injury of L. monocytogenes cells as far as possible during HHP in food industry.