Introduction

Abstract

Porosity is the ratio of the pore volume to the apparent volume of the porous medium. Food products such as baked, extruded, puffed, dried and frozen foods have an inherent porous micro-structure that gives the product its characteristic texture (Roca et al. 2006; Gogoi et al. 2000) measured in terms of physical properties such as tensile strength, compressive strength and stiffness (Stasiak and Jamroz 2009). Porosity is the macroscopic pore structure parameter which develops in conjunction with the microscopic pore structure. Microscopic pore structure parameters can be summarized as the specific surface area, average pore size and pore size distribution s based on volume, surface area and number of pores, cell wall thickness, pore shape distributions, polydispersity indices for pore sizes and shapes and the pore interconnectivity. These microscopic pore structure parameters also affect transport properties such as thermal diffusivity and moisture diffusivity as well as texture.