The optimization of radiofrequency assisted heat pump drying of Ganoderma lucidum

This study focused the optimization of radiofrequency (RF) assisted heat pump (HP) drying of Ganoderma lucidum. Response surface methodology (RSM) optimized the levels of three independent variables as the drying air temperature, the drying air velocity, and the RF power to obtain the maximum value of Polysaccharide content and minimum value of drying time. Box–Behnken design (BBD) was employed to evaluate the effects of drying air temperature, drying air velocity and RF power on drying time and Polysaccharide content in Ganoderma lucidum. The optimum predicted drying condition were the drying air temperature of 47°C, the drying air velocity of 1.53 m/s and RF power of 1.61 kW. Under the optimum drying condition, the value of Polysaccharide content and drying time have achieved 9.39 mg/g and 409 minutes. The impact of drying air temperature, drying air velocity and RF power on the drying rate and Polysaccharide content in Ganoderma lucidum after RF-assisted HP drying process was also studied. The drying rate and the Polysaccharide content increased when the drying air temperature and RF power increased, but the drying rate and the Polysaccharide content decreased when the drying air velocity increased.