Effects of pretreatments on explosion puffing drying kinetics of apple chips

•Freezing and immersion treatments were conducted on raw materials before explosion puffing drying of apple slices.•Drying kinetics for apple slices with different pretreatments were established by application of four models.•Parabolic model was found to be the best model to describe the explosion puffing drying process of apple slices.•Freezing and maltose syrup treatment exhibited the highest and lowest effective moisture diffusivity value, respectively.

In the present paper, explosion puffing drying kinetics of sliced apples affected by four different pretreatments, including freezing, maltose syrup, calcium chloride and standard pasteurized milk immersion at atmospheric pressure were investigated. Four thin-layer drying models were applied to describe the drying kinetics. The results indicated that a parabolic model was the best model to characterize the drying kinetics of apple slices. The average values of determination coefficient (r2) varied between 0.9803 and 0.9933. The parabolic model had the lowest root mean square error (RMSE), mean bias error (MBE) and chi-square (χ2), the highest modeling efficiency and regression coincident. The values of effective moisture diffusivity were ranged from 154.0650 × 10−12m2 s−1 to 397.6886 × 10−12m2s−1. Freezing pretreatment had the highest effective moisture diffusivity value and maltose syrup immersion treatment exhibited the lowest one.