Physical and Thermal Properties of Cereal Grains

Abstract

Data on physical properties of grain are essential for the design of equipment for handling, aeration, and storage, as well as processing cereal grains and other agricultural materials. Basic thermal and moisture transport properties are also required for simulating heat and moisture transport phenomena during drying and storage. The most important such properties are the grain weight, sphericity, roundness, size, volume, shape, surface area, bulk density, kernel density, fractional porosity, static coefficient of friction against different materials and angle of repose, heat capacity, thermal conductivity, thermal diffusivity, moisture diffusivity, equilibrium moisture content, and latent heat of vaporization. These properties vary widely, depending on moisture content, temperature, and density of cereal grains. The experimental measurement of the physical and thermal properties of cereal grains is the concern of postharvest technologists and researchers. Substantial research has been carried out, over the years, on gathering data for material property evaluation, and some excellent review articles have been published in various scientific journals on the physical, thermal, and moisture transport properties of plant and animal food materials (Nelson, 1973; Polley et al., 1981; Miles et al., 1983; Sweat, 1974). Several excellent books have also been published highlighting data on physical, thermal, chemical, and electromagnetic radiation properties of food and agricultural products cov-