Ultrasonic-microwave synergistic processing improvement of hot air drying efficiency for citrus Gonggan slices.

Using methods such as dynamics and thermodynamics, the drying laws, dynamic models, moisture migration, thermodynamic parameters, etc. of citrus Gonggan slices during hot air drying at different temperatures were studied. The effects of ultrasound-microwave synergistic pretreatment on the drying efficiency of citrus Gonggan slices during hot air drying were also analyzed. The results showed that the drying process followed the Two term exponential model and the drying rate was co-related with the drying temperature. The drying rate was the fastest when the drying temperature was 80 °C. The ultrasound-microwave synergistic pretreatment effectively reduced the drying time by 0. 5 hours to 1. 5 hours. The activation energy (Ea) of moisture diffusion was significantly lowered by 1. 620 kJ/ mol. At a given hot air drying temperature, the ΔH≠, ΔS≠, and ΔG≠ of the ultrasound-microwave synergistic pretreatment group were all lower than the control group. The ultrasoundmicrowave synergistic pretreatment could increase the effective coefficient of water diffusion of citrus Gonggan slices (4.333 x 10-7 to 8. 967 x 10-7), resulting in more pores on their surfaces. Therefore, the ultrasound-microwave synergistic pretreatment could effectively improve the hot air drying efficiency of citrus Gonggan slices. [ABSTRACT FROM AUTHOR]