The safety and/or quality of a food is determined by the effect of all reactions occurring in the product, integrated over the full history of the product until the moment of consumption. In Figure 13.1, the idea of a “preservation reactor” is presented. This concept applies to the entire process of manipulating a food product — preparation and packaging, processing, distribution to storage — as well as to a single unit operation or processing step in the production chain. The rates at which desired (e.g., microbial inactivation) and undesired (e.g., nutrient destruction) reactions related to food safety and quality take place are functions of intrinsic (i.e., food-specific) properties and extrinsic (i.e., process-specific) factors (1,2).