Thermal conductivity of granular rice starches

Thermal conductivities of four types of granular rice starches, regular, low protein, waxy and low protein waxy, were measured at bulk densities of 600 and 800 kg/m3, temperatures of 20, 50 and 80 °C, and moisture contents of 4, 20 and 40% (wet basis), using a line-source thermal probe system equipped with a computerized data acquisition system. A completely randomized experimental design with factorial treatment structure resulted in a total of 72 treatments, each with 3 replications. The thermal conductivity was significantly different among various rice starches. Low protein and waxy rice starches had higher thermal conductivities than regular and low protein waxy rice starches. Thermal conductivity increased significantly with increases in bulk density, temperature and moisture content. Prediction models were developed to calculate thermal conductivity values for practical applications.