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

Predictive microbiology requires a sound basis of observed results, and factors that contribute to death of bacterial cells, before accurate equations can be developed. The effect of chilling and freezing strains of Escherichia coli and salmonella serotypes in nutrient broth, a noninhi-bitory liquid medium, was investigated. The phase of growth, small changes in composition of test medium, and sub-cultures made after primary isolation, influenced survival. Therefore, such influences must be considered when attempting to extrapolate results Erom pure cultures on laboratory media, to predict behavior of similar organisms in foods during chilling and freezing.