Chapter 1 - Physical Properties of Food Materials

Abstract

This chapter discusses the physical properties of food, properties that lend themselves to description and quantification by physical rather than chemical means. The physical properties of foods are of utmost interest to the food engineer, mainly for two reasons: many of the characteristics that define the quality (e.g., texture, structure, appearance) and stability (e.g., water activity) of a food product are linked to its physical properties and quantitative knowledge of many of the physical properties, such as thermal conductivity, density, viscosity, specific heat, enthalpy and many others, is essential for the rational design and operation of food processes and for the prediction of the response of foods to processing, distribution, and storage conditions. Some of the engineering properties will be treated in connection with the unit operations where such properties are particularly relevant (e.g., viscosity in fluid flow, particle size in size reduction, thermal properties in heat transfer, diffusivity in mass transfer etc.). Properties of more general significance and wider application are described in this discussion.