Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2002
Publication Date: 6/20/2002
Citation: Juneja, V.K. 2002. Predictive models for Clostridium perfringens applicable to cooling. (Abstract) International Association Food Protection. S-13.
Technical Abstract: Inadequate cooling of foods in retail food operations is a major safety problem. Accordingly, the objectives of these studies were to determine a safe cooling rate for cooked beef and develop models to predict the germination, outgrowth and lag (GOL), and exponential growth rates (EGR) of Clostridium perfringens from spores. C. perfringens growth from spores was snot observed at a temperature of 12C for up to 3 weeks. First, we demonstrated the effectiveness and validity of the "square-root model" under non-isothermal conditions. Next, we developed predictive models to predict C. perfringens growth from spores at temperatures applicable to the cooling of cooked, cured and uncured, meat products. From the parameters of the Gompertz or logistic function the growth characteristics, GOL times and EGR, were calculated. These growth characteristics were subsequently described by the Ratkowsky function using temperature as the independent variable. By applying multivariate statistical procedures, confidence intervals were computed on the predictions of the amount of relative growth for a given temperature. Closed form equations were developed that allow prediction of growth for a general cooling scenario and the standard error of the prediction. For example, the model for cured beef predicts a relative growth of 3.17 units with an upper 95 percent confidence limit of 8.50 units when cooling the product from 51C to 11C in 8 h, assuming log linear decline in temperature with time. The predictive models have been converted into an easy-to-use computer program that is available for use at the USDA- Eastern Regional Research Center website. This pathogen modeling program should aid in evaluating the safety of cooked product after cooling and thus, with the disposition of products subject to cooling deviations.