Combined drying technology of black edamame using microwave and explosion puffing

Microwave and explosion puffing combination drying were used to improve quality of black edamame puffed product. Microwave drying characteristics of black edamame at different microwave power per unit mass were studied. The effects of the water content rate at transformation point, pressure difference, puffing temperature, dwell time and vacuum drying time on the water content, hardness, brittleness and color of puffed product were investigated. The results showed that when microwave power per unit mass were 5 W/g, the high drying rate and relative short drying time were obtained. The water content rate at transformation point, puffing temperature and vacuum drying time had significant effects on the quality indexes of puffed product, while pressure difference and dwell time had little effects. The optimal processing parameters during combination drying were microwave power per unit mass of 5 W/g, the water content rate of 31% at transformation point, pressure difference of 0.124 MPa, puffing temperature of 100℃, dwell time of 10 min and vacuum drying time of 90 min. The results can provide references for industrialized production of black edamame drying.