Proteolytic Clostridium botulinum growth at 12-48 degrees C simulating thecooling of cooked meat: development of a predictive model

The objective of this study was to develop a model to predict the germinati on, outgrowth and lag (GOL) and exponential growth rates of Clostridium bot ulinum from spores at temperatures (12-48 degrees C) applicable to the cool ing of cooked meat products. The growth medium, Reinforced Clostridial medi um (RCM) supplemented with oxyrase enzyme to create suitable anaerobic cond itions, was inoculated with approximately 4 log(10) spores ml(-1). Clostrid ium botulinum populations were determined at appropriate intervals by plati ng onto RCM. Clostridium botulinum growth from spores was not observed at t emperatures < 12 degrees C or > 48 degrees C for up to 3 weeks. Growth curv es were determined by fitting Gompertz functions to the data. From the para meters of the Gompertz function the growth characteristics, GOL times and e xponential growth rates were calculated! These growth characteristics were subsequently described by Ratkowsky functions using temperature as the inde pendent variable. Closed form equations were developed that allow for predi cting relative growth for a general cooling scenario. By applying multivari ate statistical procedures, the standard errors and confidence intervals we re computed on the predictions of the amount of relative growth for a cooli ng scenario. The predictive model is capable of predicting spore outgrowth and multiplication for general cooling scenarios, for suitable but unverifi ed mathematical assumptions, and should aid in evaluating the safety of coo ked products after cooling. (C) 1999 Academic Press.