Validation of industrial radio frequency treatment protocols to control Lasioderma serricorne in tobacco leaves

Radio frequency (RF) heating has been demonstrated as an effective postharvest disinfestation technology, making it a viable option for controlling major pests in tobacco leaves, such as Lasioderma serricorne (F.) (Coleoptera: Anobiidae). In this study, a 27.12 MHz, 6 kW RF heating system equipped with an internal forced hot air system was employed for disinfesting tobacco leaves. The top surface of tobacco leaves was photographed by a thermal imaging camera to evaluate the RF heating uniformity. The key parameters including electrode gap and conveyor belt speed were optimized to evaluate the pest mortality, RF heating uniformity and physic-chemical quality of tobacco leaves. Results showed that the electrode gap of 150 mm was chosen according to the suitable heating rate. The RF treatment was determined with the conveyor belt speed of 7.7 m/h and forced hot air temperature of 57 °C so as to enhance the RF heating uniformity. The optimized protocol achieved 100 % pest mortality by heating tobacco leaves to 57 °C and holding for 3 min. Quality analysis revealed acceptable changes in moisture content (12.91 % w.b.), adhesion force, color (ΔE < 1.3), and chemical composition (total sugar, total nitrogen, and nicotine). This study developed an effective industrial scale RF process as a reliable alternative to chemical fumigation for pest control in tobacco leaves.