Temperature effect on Listeria monocytogenes growth in the event of contamination of cooked pork products

The aim of this study was to describe the effect of temperature on the growth of Listeria monocytogenes in the event of postprocess contamination of packaged pork meats. This study was carried out in two steps. In the first step, the effect of temperature on L. monocytogenes growth rates was determined in duplicates at 13 temperatures between 2 and 43 degrees C by turbidimetric methods and adjusted by a quantitative secondary model. Then, seven sets of growth kinetics were collected by challenge testing in white pudding and roulade, both cooked pork products prepared according to an industrial process and stored at suboptimal temperatures ranging from 2 to 20 degrees C. In the second step, objectives were to (i) collect direct information on the temperature effect of L. monocytogenes on the two pork products, (ii) compare the two products regarding L. monocytogenes exposure, and (iii) compare results given by modeling (step i) with results obtained independently and then evaluate the model application domain. Each kinetic was built with at least 10 experimental data and two replicates. Comparison between L. monocytogenes behavior at 4 degrees C on white pudding and roulade indicated that both meat products were affected by food safety problems. Indeed, after contamination and storage for 10 days at 4 degrees C, the bacterial population increased by 2 log CFU/g in both products. Comparison between growth kinetic simulations and experimental data obtained separately gave satisfactory conclusions; the difference between observed and predicted bacterial population values was always less than 1 log CFU/g and a bias factor of 1.18 when growth rates were compared. These results applied to L. monocytogenes contamination of white pudding or roulade can now be used either in the management of optimal process and distribution networks or in risk assessment (exposure assessment).