Effect of freeze-hot air drying on the quality of dried mulberry

In order to improve the quality of dried mulberry， the effect of freeze drying， hot air drying and freeze-hot air drying on the quality of mulberry was investigated. The color， hardness， crispness， rehydration ratio， the content of total anthocyanins and individual phenolic compounds， and DPPH radical scavenging activity were determined. Results showed that the quality of freeze dried mulberry fruits was best. However， short time（ 18-24 h） freeze drying combined with high temperature（ 85℃） hot air drying could improve drying efficiency. The contents of total anthocyanins， chlorogenic acid and rutin in freeze-hot air drying mulberries were significantly higher than those in hot air drying fruits. Correlation analysis also showed that total phenolics， total anthocyanins， cyanidin- 3-glucoside， cyanidin-3-rutinoside， quercetin， chlorogenic acid content had significant positive correlation with antioxidant capacity.