Comparative effects of improved schemes with shape adjustment and composite packaging on radio frequency heating of two-component rice

Abstract

To meet the demand for uniform reheating of two-component instant foods and address the uneven temperature distribution during radio frequency (RF) heating identified in previous sensitivity analysis, three improvement schemes with shape adjustment and composite packaging (annular protrusion (AP) of cooked rice, top composite plate (TCP), and bottom composite plate (BCP)) were developed based on screened system variables with positive effects. An integrated structural (INS) plan was then designed by combining the respective strengths of the three evaluated schemes of AP, TCP, and BCP. The RF heating performance of the selected INS sample was evaluated through simulation, some validated by experimental results. The results showed that the AP scheme achieved the relatively better uniformity in temperature distribution while ensuring rapid heating. The TCP and BCP schemes effectively adjusted the location of high-temperature region vertically and horizontally, respectively. Among all, the INS (H12.0-D40.0) sample was found to be the optimal scenario under the relatively high heating rate of 19.3 °C/min and the most uniform temperature distribution with experimental temperature uniformity index (0.038) for the whole sample and simulated heating uniformity index (0.043) for the diagonal longitudinal section. The proposed improvement schemes in this study and the relevant integration methodology of respective advantages may offer theoretical support for enhancing RF heating uniformity in other heterogeneous food products.