Effect of Ultrasonic Pretreatment on Radio Frequency Vacuum Drying Characteristics and Quality of Codonopsis pilosula Slices

In this paper, the effects of ultrasonic pretreatment on drying kinetics, bioactive components (polysaccharides, total phenols, flavonoids and antioxidant), qualitative characteristics (color index, lobetyolin syringin) microstructure Codonopsis pilosula during radio frequency vacuum (RFVD) were studied. The average rate curve showed that whole process could be divided into three stages: accelerating period, constant period falling period. Deff values ranged from 6.61425 to 9.46745 × 10−8. Analysis constants revealed different conditions effective in increasing rate. Ultrasonic has a positive effect retention polysaccharide content; low favors syringin; with increase time power, antioxidant capacity was higher than without treatment. significantly improved color microstructure. summary, condition 20 kHz power 60 W for 30 min is suitable, which provides certain reference application technology RFVD slices.