干燥方式对蓝莓花青素降解特性及抗氧化能力的影响

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

目的:降低干燥过程中蓝莓花青素类物质的降解。方法:将远红外干燥应用于蓝莓的干燥中,并与传统热风干燥进行对比,探究不同干燥方式下蓝莓中主要花青素的降解特性、PPO酶活性及抗氧化能力变化。结果:远红外干燥下的蓝莓中两种主要花青素(D3G及C3G)保留率较高,二阶数学模型能够更好地模拟其降解过程。与热风干燥相比,远红外干燥蓝莓花青素的动力学速率常数k值及熵ΔS值更小,半衰期t1/2值、活化能Ea值及焓ΔH值更大。两种干燥方式对PPO酶活性产生了相似的影响,但干燥4 h后远红外干燥组酶活性总体低于热风干燥组。此外远红外60℃干燥条件下观察到了蓝莓干果最高的花青素保留率及自由基清除能力。结论:相同干燥温度条件下,远红外干燥相较于传统热风干燥能够减少蓝莓在干燥过程中花青素类物质的降解,提高干燥品质。

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.