ABSTRACT
Obviously, inactivation of microorganisms in raw materials and food is necessary for food safety and food quality. It is no coincidence that the first kinetic principles in food technology were developed with respect to inactivation of microorganisms because of its importance. In the 1920s, the concept of D-and Z-values was developed by Esty and Meyer and Bigelow, and later taken up by Ball and Stumbo in F-values. The term ‘‘thermobacteriology’’ was coined and pioneered in the canning industry and the ‘‘12D concept’’ is widely accepted. This means that sterilized foods have at least a 12 decimal log reduction of the most dangerous (because of its very potent toxin botuline) bacterium Clostridium botulinum, so that sterile food is virtually always free from spores of this dangerous species. These ideas are still in use today. We have shortly discussed the D and Z concept in Chapter 5. Here we further elaborate on this matter and investigate whether the classical first-order inactivation kinetics approach is still a valid method or that alternative methods are needed. Like the microbial growth kinetics issue discussed in Chapter 12, the topic of microbial inactivation is also under heavy debate. Moreover, nonthermal treatments are becoming in vogue and the consequences for microbial activity in foods need to be considered.
