Chapter 17 - Thermal Treatment

Abstract

Thermal treatments of various time–temperature combinations are commonly applied in the food industry for the inactivation or decrease in number of microorganisms in order to manufacture safe products with a long shelf-life. Food processing involves unit operations of heating (e.g. cooking, boiling, blanching) as well as final heat treatments such as pasteurization and sterilization. This chapter outlines the fundamentals of thermal death of microorganisms on which the processes of thermal treatment are based. The first part discusses the kinetics of thermal destruction and heat resistance of microorganisms. Conventional thermal treatments with high temperatures such as widely applied for sterilization in canning, and factors influencing thermal treatment and the concept of commercial sterility will be described. The next part will deal with the methods of milder heat treatment for pasteurization of products often used in combination with additional measures of preservation. The final part of the chapter is devoted to novel non-conventional methods of heat treatment applying electrical techniques to generate heat instead using the traditional wet steam. Combined and non-conventional thermal treatments are being developed to meet consumers’ demand for better preserving natural quality foods while assuring safety. Understanding these concepts is essential for designing and validating measures for the control of biological hazards.