Chapter 4 - Heat Transfer in Food Processing

Abstract

Heat transfer is ubiquitous in food processing. Heat exchangers are commonly used for the purposes of heating and cooling foods. In designing heating or cooling systems, thermal properties of foods and food contact materials are required. The key thermal properties include specific heat, thermal conductivity, and thermal diffusivity. Heat exchange between a heating or cooling medium and food occurs by conduction, convection and/or radiation. Mathematical expressions are useful in determining the rate of heat transfer and for designing process equipment. Heat transfer calculations are conducted for steady state and unsteady state conditions. Most common shapes of heat exchangers used in food processing are either tubular or plate. Fouling is a common occurrence in thermal operations and its impact on heat transfer can be determined with appropriate expressions. Dimensionless relationships involving Biot number, Prandtl number, and Fourier number are used in determining unsteady state heat transfer. Understanding mechanisms that are involved in heating foods in a microwave field is necessary to develop novel foods for microwave applications.