Abstract:Cold air drying can get high quality products，but its drying time is long and its drying efficiency is low.In order to improve the cold air drying efficiency of maca slices，low frequency ultrasound was involved in the cold air drying process of maca slices.The effects of ultrasonic power and cold air drying temperature on maca cold air drying characteristics，product color difference，rehydration ratio and the content of macaramide were studied，and the mathematical model between each index and drying parameters was obtained by stepwise regression analysis.Weibull distribution function was used to fit the drying process to characterize the drying kinetics of maca cold air under the intervention of low frequency ultrasound.The results showed that the drying time of maca decreased with the increase of ultrasonic power and drying temperature.Weibull distribution function could characterize the drying kinetics of maca cold air under ultrasonic intervention，and the whole drying process was in the stage of decreasing drying.The effective moisture diffusion coefficient of maca low frequency ultrasound combined with cold air drying was in the range of 5.15×10-10m2/s-9.52×10-10m2/s，and the quality of dry products could be improved by the intervention of low frequency ultrasound.The low-frequency ultrasound could be used as an effective means to intervene in the cold-air drying process of the macula so as to improve the drying efficiency and the product quality.