ABSTRACT
Heating is probably the cheapest and most ef‘cient preservation method; its main objective is to ensure the destruction of most pathogens and spoilage microorganisms and to inactivate enzyme, in such a way as to prevent spoilage reactions and proliferation of undesirable microŽora. Depending on the expected shelf life, a speci‘c food is subjected to a set of conditions, of varying intensity. If a food is cooked, only partial elimination of spoilage microorganisms and enzymes takes place, but additional preservation methods are necessary; conversely, canning allows the destruction of virtually all microorganisms and their spores, able to proliferate and/or produce toxins, specially Clostridium botulinum, as well as spoilage microorganisms. The result of some thermal-processing methods, such as canning, is the production of self-stable foods, with a considerably long shelf-life, without the need of applying and other special storage conditions. However, thermal processing usually alters sensory and physical characteristics; in some cases, changes in physical structure are highly desirable, and are even part of the process itself, as is the case of luncheon meat where an emulsion system changes to a gel as a result of thermal processing.
