Heat resistance of coliform species isolated from cooked ham, snail flesh, and "bouchées à la reine"

Abstract : Aims: In this study, the heat resistance of coliform species isolated from cooked ham and ready-made meals was determined. Methods and Results: Thirteen coliform strains belonging to 12 different species were studied using laboratory medium in order to determine δ (first decimal reduction time) and zT values temperature increase leading to a 10-fold reduction of δ) using the Weibull model. For seven strains, δ-values were determined at temperatures ranging from 55 to 60°C, with, δ values between 0-52 and 2-98 min, at 59°C. For the other six strains, lower temperature values were determined with δ-values ranging from 0-47 to 1-64 min at 54°C. zT values calculated for the 13 strains were 3-1 to 7-5°C. For eight strains, plotting of the log of survivors was not linear but rather showed shoulders or shoulders and tails. Conclusions: Coliform species were sensitive to heat treatment with a decimal reduction time under 2 min at 60°C. Significance and Impact of the Study: The better knowledge of coliform heat resistance by determining thermal resistance parameters with confidence intervals will be useful for evaluating the efficiency of industrial thermal processes.