Effects of various directional movements of milled rice on radio frequency heating uniformity

Abstract

Abstract Mixing and moving of samples during radio frequency (RF) processing have been demonstrated to be efficient ways for improving the heating uniformity. However, the current single or limited moving direction of samples requires a comprehensive and systematic investigation of combined movements in multi-directions. The purpose of this research was to compare the RF heating uniformity of milled rice with movement and layer/part rearrangement in three directions, as well as mixing. The results showed that the RF heating uniformity was not significantly (P\xa0>\xa00.05) improved when the rice samples were moved horizontally and only under the top electrode, while slightly improved for moving the rice samples gradually in and out of the two sides below the top electrode. Moving samples in vertical direction, rearranging sample parts horizontally and layers vertically all clearly improved the RF heating uniformity. Mixing with two times was the most effective method to improve the RF heating uniformity. These results may provide the useful methods to ensure the RF heating uniformity in industrial applications and help to develop effective RF treatment protocols in low-moisture granular agricultural products.