Effects of Conveyor Movement, Layer Rearrangement and Sample Mixing on Pest Mortality in Milled Rice Subjected to Radio Frequency Heating

Abstract

Highlights Hot air-assisted RF heating accelerated temperature rise of samples. Thermal holding after RF heating improved heating uniformity and pest mortality. Layer rearrangement, conveyor movement, and mixing enhanced RF heating efficiency. Abstract. Application ofradio frequency (RF) treatment has been studied for disinfesting agricultural products, and RF heating non-uniformity has been demonstrated to directly influence pest mortality in treated products. The purpose of this study was to investigate the combined effects of holding time after conveyor movement, layer rearrangement, and sample mixing on the mortality of Rhyzopertha dominica (R. dominica) in milled rice treated with hot air-assisted RF heating. Results showed that hot-air assistance during the process of RF heating can lead to a rapid temperature rise and improve the temperature distribution. RF heating followed by holding samples in hot air for specific time periods effectively improved the heating uniformity of samples and raised the mortality of R. dominica in milled rice. Compared with the stationary conditions, conveyor movement, layer rearrangement, and sample mixing improved the hot air-assisted RF heating uniformity of the sample, raised pest mortality and reduced the thermal holding time after RF treatment required to achieve 100% pest mortality in milled rice. The findings of this study provide a valuable proof of concept for improving RF heating uniformity and optimizing parameters in RF disinfestation protocols for milled rice. Keywords: Heating uniformity, Milled rice, Mixing, Pest mortality, Radio frequency heating.