Theoretical and Practical Aspects of Rough Rice Tempering

ABSTRACT A theoretical model was developed to simulate the dry-ing and tempering of rough rice. The model was bas-ed on liquid diffusion theory and assumes the grain to consist of a spherical core (starchy endosperm) surround-ed by two concentric shells (bran and hull respectively). During tempering, measured changes in relative humidi-ty in the void volume of a mass of rough rice were com-pared to predicted changes in surface liquid concentra-tion of a rough rice kernel. The results of modeling are presented in terms of equations which predict tempering time. The effects of drying variables on the tempering model were investigated. Multipass drying was simulated to determine how various degrees of tempering effected the drying curve.