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

Abstract

Microorganism control methods in food, medical, and environmental fields include killing, inhibition, removal (e.g., washing) , and interception (e.g., packaging) , which can be broadly classified into physical, chemical, and biological methods. Each of these methods has its advantages as well as disadvantages, and in practice, two or more of these methods are often used in combination to decontaminate objects or places (Russell 1982;Gould and Jones 1989;Shibasaki 1998) . In medicine, combination treatments are used in chemotherapy, including antibiotics, anticancer drugs, and anti-AIDS drugs, against pathogens. In addition to drug combinations, cancer drugs are also used in combination with radiation and heat (hyperthermia) . In food, the concept of combination treatments against harmful microorganisms is known as hurdle technology (Leistner 1995;Ray 2004) . This is the idea that each control method can be viewed as a hurdle and that combining two or more hurdles can inhibit microbial growth. In the food industry, various combinations of physical as well as chemical control methods have been used, and modeling of their control effects has been attempted (Peleg 2000) , but a comprehensive theory has not yet been established. Software tools that can be utilized in food manufacturing have not yet been developed due to the diversity of food, target microorganisms, and operating factors in the process. The main objectives of the application and study of combined treatment in food, especially in processed food are: 1) to obtain effectiveness by complementing the shortcomings of the mutual control methods in terms of not only the effect of microorganism control but also the effect on the quality, economy, operability, safety and wholesomeness, and environmental compatibility; 2) the expectation of a synergistic effect compared to the effect of a single treatment, and 3) conformity with practical constraints and compliance with, laws, regulations, and guidelines. TYPES OF COMBINED TREATMENTSIn the application of microorganism control treatment, especially in processed food, there are many consecutive treatments in the manufacturing process. The quality of ingredients and food products must be maintained during operations such as sterilization, refrigeration, packaging, etc.