Growth of Clostridium perfringens in roasted chicken and braised beef during cooling – One-step dynamic analysis and modeling

Abstract

Roasted chicken (RC) and braised beef (BB) are two important commercial products widely consumed in China. Prepared with a mixture of different spices and other ingredients, these products may be contaminated with Clostridium perfringens spores. The spores may germinate, outgrow, and multiply to a dangerous level during cooling after cooking if the cooling process is not sufficiently fast, causing outbreaks of food poisoning due to production of C. perfringens enterotoxin.This study was conducted to investigate the growth of C. perfringens from spores in these products under various cooling conditions and to develop predictive models. Inoculated samples were exposed to different cooling profiles to observe the bacterial growth. Analyzed with the one-step dynamic kinetic analysis method, various kinetic parameters were determined. The estimated Tmin, Topt, and Tmax were 8.8, 46.4, and 51.5 °C in RC, and 10.3, 43.5, and 53.4 °C in BB, all agreeing well with the cardinal temperatures of this microorganism in meats. The optimum specific growth rate (μopt) was 6.06 ln CFU/g per h in RC, and 5.64 ln CFU/g per h in BB.The validation of the growth models showed that the RMSE of prediction was relatively low (0.2–0.3 log CFU/g). The majority (94%) of the residual errors of prediction was within ±0.5 log CFU/g, and 76% within ±0.3 log CFU/g of the experimental observations. While accurate, the predictions are mostly fail-safe. The estimated kinetic parameters and predictive models developed in this study can be used to predict the growth of C. perfringens in RC and BB during cooling after cooking to prevent the outbreaks caused by the growth of this pathogen.