Effect of hybrid drying methods on physicochemical, nutritional and antioxidant properties of dried black mulberry

The effect of hot air drying (HAD), freeze drying (FD), hot air-explosion puffing drying (HA-EPD) and freeze-explosion puffing drying (F-EPD) on the physicochemical, nutritional and antioxidant properties of black mulberries were investigated. F-EPD products showed the best texture attributes (hardness 29.46 N, crispness 30, rehydration ratio 1.65 g/g), better colour (hue angle of 0.03) and the highest overall score of sensory evaluation. Although the highest retention of anthocyanin contents and antioxidant activities were found in FD samples, the products had the lowest crispness (3). Compared to HA-EPD and HAD, higher content of anthocyanin (12.38 mg/g), cyanidin-3-glucoside (8.60 mg/g) and cyanidin-3-rutinoside (2.62 mg/g) remained in F-EPD products, as well as DPPH scavenging ability and ferric reducing power (91.53 and 120.59 mg trolox equivalent/g, respectively). Hence, F-EPD could be a more promising technique to develop the dried products of black mulberries. Correlation analysis results showed that cyanidin-3-glucoside content had significant positive correlation with antioxidant capacity.