Food engineering and predictive microbiology: on the necessity to combine biological and physical kinetics

Predictive microbiology is mainly applied in the area of risk assessment, but unusually regarded as a tool for the optimisation of processes, which needs the implementation of food engineering. Combination of predictive microbiology and food engineering allows both the assessment of a process in relation to risk and its optimisation. Intrinsic comparison between processes in relation to risk, on one hand, and the development of process optimisation tools on the other hand, necessitates the implementation of new concepts and the involvement of simplified and standard calculations based upon reference target strains and environmental conditions. Some conventional concepts related to heat treatments are extended, while some new ones related to bacterial growth are derived from the gamma concept of Marcel Zwietering.