Calculation of the expected increases of coliform organisms,Escherichia coliandSalmonella typhimurium, in raw blended mutton tissue

Abstract

SUMMARYSamples of blended mutton tissue in small polyvinyl chloride sachets were incubated in water baths for different times and at varying temperatures. The temperature of each bath was recorded accurately throughout each experiment. Using equations previously derived for the lag and generation times of coliform organisms in blended mutton tissue, the expected increases of these bacteria were calculated from the time/temperature recordings. These were compared with the data obtained from plate counts made on the tissue samples in the sachets before and after incubation. The studies were done with a strain of Escherichia coli, one of Salmonella typhimurium and the coliform organisms naturally present on sheep carcasses processed in a commercial abattoir. The calculated growth agreed closely with that measured. Therefore, if mutton, after overnight chilling, is warmed again to temperatures within the growth range of these bacteria, the possible increases in the numbers of cells present can be calculated directly from time and temperature measurements.The implications for the present codes of practice in abattoirs are discussed.

Survival of E. coli and Salmonella after Chilling and Freezing in Liquid Media

“…DEATH OR INJURY OF BACTERIA caused by chilling to temperatures slightly above ice formation (chill shock), or by freezing to <O"C, is an important aspect of refrigerated storage of food (Speck and Cowman, 1969). It is especially important in regard to survival of species of Enterobacteriaceae which include foodpoisoning organisms such as Salmonella, some Aeromonas strains, and the enteropathogenic Escherichia coli.…”

“…These could be used subsequently to calculate the expected increase of such bacteria under different, even constantly changing, conditions (Smith, 1987). Those results have been used to develop other mathematical models to represent the growth of such bacteria (Davey, 1991;Ratkowsky et al, 1991).…”

Survival and growth characteristics of bacteria in irradiated meat

“…In kinetic modeling, one approach is to model growth rate to make predictions based on exponential population growth. This approach has been used by a number of groups (Broughall et al 1983;Smith, 1987;Blakenship et al 1988;Fu et al 1991;McMeekin et al 1993). The other approach, introduced by , is a sigmoid function fitted to the observed population growth curve and the effect of environmental factors on the values of parameters of that fitted sigmoid curve are modeled.…”