Abstract:To investigate the rotating tray microwave vacuum drying characteristics and quality attributes of kiwifruit slices, the effects of different microwave power density (3.33W/g, 6.25W/g and 9.58W/g),drying temperature (40℃, 45℃, 50℃ and 55℃), vacuum holding pressure (20kPa, 15kPa,10kPa and 5kPa) and slice thickness (3mm, 6mm, 9mm and 12mm) on the drying kinetics of kiwifruit slices were analyzed. Weibull function and neural network model were also compared to choose the appropriate fitting model for kiwifruit slices drying. The results suggested that rotary tray microwave vacuum drying can greatly increase the material loading capacity. Meanwhile, the drying uniformity was increased by 16% compared with the traditional vacuum microwave drying method, and the average energy consumption was only 71.2% of the latter, which ensured excellent drying quality under the mass processing of kiwifruit slices. With the decrease of power density and the increase of slice thickness, there was a more obvious constant speed section in the process of material drying. When the moisture content of kiwifruit slices (dry base) dropped to about 1.3g/g, the drying process changed to the speed reduction stage. The drying rate was added with the increase of microwave power density, drying temperature and vacuum holding pressure, as well as the decrease in slice thickness. Properly reducing the power density and drying temperature, increasing the vacuum degree and thickness can improve the quality attributes of dry products. The optimization parameter was confirmed at the power density of 6.25W/g, drying temperature of 45℃, vacuum holding pressure of 5kPa and the thickness of 6mm. By analyzing the predicted values of two models, the determination coefficient (R2) of neural network model can reach up to 0.996 and the root mean square error (RMSE) was 0.0216, which had better simulation precision than that of Weibull model and it can predict the water transfer law of kiwifruit accurately during microwave vacuum drying. The research reuslt provided a scientific reference for the mass production of kiwi fruit slices during the pilot stage.