Effects of different drying methods on degradation characteristics of anthocyanins and antioxidant capacity in blueberries

Objective: Reducing the degradation of anthocyanins in blueberry during drying. Methods: The far infrared drying was applied to the drying of blueberries, and compared with traditional hot air drying to explore the degradation characteristics of major anthocyanins and the changes of PPO enzyme activity and antioxidant capacity of blueberries under different drying methods. Results: High retention of two major anthocyanins （D3G and C3G） in blueberries under far-infrared drying, and the second-order mathematical model could better simulate their degradation process. Compared with hot-air drying, the rate constants （k） and entropy values （ΔS） of far-infrared dried blueberry anthocyanins were smaller, and the half-life values （t1/2）, activation energy values （Ea） and enthalpy values （ΔH） were larger. The two drying methods produced similar effects on PPO enzyme activity, but the enzyme activity of the far-infrared drying group was generally lower than that of the hot-air drying group after 4 h. In addition, the highest anthocyanin retention and free radical scavenging ability of dried blueberry fruits were observed under far-infrared 60 ℃ drying conditions. Conclusion: Under the same drying temperature, far-infrared drying can reduce the degradation of anthocyanins and improve the drying quality of blueberries compared with traditional hot air drying.