Combined effects of microorganism control and the concept of their evaluation methods

Various combination treatments are used for microorganism control in food, medicine, and the environment. Especially in food, combination treatments have been studied using antimicrobial compounds in pasteurization and sterilization but comprehensive quantitative evaluation methods, have not yet been established to evaluate their effectiveness. This review introduces the author's recently published methods for evaluating the effects of combination treatments on the control of harmful microorganisms in food. Particularly important items are 1) the type of action of the control treatment and the mode of the combined method, 2) the choice of endpoint method and growth delay method for analytical evaluation, 3) the construction of extended isobolography that allows the application of conventional isobologram (IBo) for chemicals to various control methods, 4) the extended use of combined index (CI）, and 5) the introduction of synergistic parameter (SP) for quantitative evaluation of synergistic effects. In addition, I describe the characteristics of the action of antimicrobial compounds and disinfectants in their combined effects with heating, and insist on the advantages of using combined treatments and their evaluation methods in the food industry.