Radio frequency heating for corn seeds: Model development and uniformity optimization

Abstract

Radio frequency (RF) heating has been considered as a promising method for food pasteurization and disinfestations, materials and heating uniformity are the main considerations in developing and scaling-up RF treatment protocols. In this study, an experimentally validated model of corn seeds was developed to investigate its RF heating characteristics and effects of sample shape on heating uniformity. Results showed that hot spots distributed in the corners and edges but cold ones in the centre of the rectangular sample, which led to the concentration of electric field at the sample edges, thus increased their electric field intensity and loss power. Comparing the temperature distributions of corn samples in six shapes, the best heating uniformity was observed in the special round sample (round corners, edges and surfaces), its uniformity index was 0.04, as its special round surface made the direction of the electromagnetic field in the sample incline to the centre, and homogenized the electric field intensity and loss power density. The results provide an evidence for temperature prediction and uniformity improvement of corn seeds during RF heating.