ABSTRACT

Thermal inactivation of microbial cells, bacterial spores, and enzymes has been and will remain one of the most effective ways to assure food safety and stability. The governing philosophy has been to identify the most heat-resistant agent of spoilage or of potential health risk and then create time-temperature conditions that will eliminate it even at the coldest point of the food. Once accomplished, this would guarantee that “all” potentially harmful or undesirable agents have been destroyed “everywhere” in the product and hence, that the food will remain biologically stable and safe for as long as its container remains hermetically sealed. Finding the coldest point requires knowledge of heat transfer theories, or a series of measurements. Identifi cation of the pertinent target, be it a bacterial endospore, microbial cell or an enzyme, and determination of its heat resistance, requires knowledge of food microbiology and biochemistry. We will assume that knowledge of both kinds already exists or can be created by collection of pertinent experimental data. Therefore, we will limit our discussion to methods of calculating or estimating the effi cacy of thermal processes in terms of the theoretical extent of the inactivation at the coldest point, regardless of whether it has been determined directly or through heat transfer models.