不同干燥方式对甘薯叶理化特性和抗氧化能力的影响

目的 探究三种不同干燥方式(微波干燥、热风干燥、冷冻干燥)对甘薯叶物化特性的影响。方法 以新鲜甘薯叶为原料,探究三种不同干燥方式对甘薯叶基本成分(水分、蛋白质、总膳食纤维、粗脂肪、可溶性糖、总酚、总黄酮和绿原酸含量)、物化特性(色度、微观结构、胆固醇吸附能力、持水力、持油力和葡萄糖吸附能力)和抗氧化活性(DPPH.清除率、ABTS法自由基抑制率、总还原力和.OH清除能力)以及酚类物质的组成等影响。结果 不同干燥方式对甘薯叶基本成分的影响中,利用热风干燥的甘薯叶水分含量最高,为7.96 g/100 g；冷冻干燥含水量最低,为7.29 g/100 g；冷冻干燥的蛋白质含量、粗脂肪、总酚、总黄酮以及绿原酸含量最高,分别为31.39 g/100 g、3.43 g/100 g、50.73 mg CAE/g DW、18.49 mg RE/g DW、7.05 mg/g DW；热风干燥的总纤维含量最高,为28.8 g/100 g。不同干燥方式对甘薯叶理化指标的影响中,利用冷冻干燥的甘薯叶色泽品质明显优于热风干燥和微波干燥；热风干燥的胆固醇吸附能力和持油力最强,分别为0.23 mg/mL,1.54 g/g；冷冻干燥的持水力和葡萄糖吸附能力最优,分别为7.33 g/g和12.00 mmol/g。抗氧化性上,不同方法测定的抗氧化能力都表现为冷冻干燥＞微波干燥＞热风干燥,冷冻干燥的总还原力、DPPH.清除能力、.OH清除能力、ABTS+^{清除率分别高达}83.34、41.28、9.17、27.21 mg Vc/g。结论 冷冻干燥最适合用来对甘薯叶进行干燥处理。

Effects of different drying methods on physicochemical properties and antioxidant capacity of sweet potato leaves

Objective To investigate the effects of three different drying methods (hot air drying, vacuum freeze drying, microwave drying)on physicochemical characteristics of sweet potato leaves. Methods Fresh sweet potato leaves were used as raw materials to explore the effects of three different drying methods on the basic components (moisture, protein, total dietary fiber, crude fat, soluble sugar, total phenol, total flavone and chlorogenic acid contents), physicochemical properties (chroma, microstructure, cholesterol adsorption capacity, water retention, oil retention and glucose adsorption capacity) and antioxidant activities (DPPH. scavenging rate, ABTS radical inhibition rate, Total reducing power and .OH scavenging capacity) and the composition of phenolic substances. Results Among the effects of different drying methods on the basic components of sweet potato leaves, the moisture content of sweet potato leaves using hot air drying was the highest, which was 7.96 g/100 g. While using freeze drying water content was the lowest, which was 7.29 g/100 g. The contents of protein, fat, total phenol, total flavonoids and chlorogenic acid in freeze-drying were the highest, which were 31.39 g/100 g, 3.43 g/100 g, 50.73 mg CAE/g DW, 18.49 mg RE/g DW and 7.05 mg/g DW, respectively. The total fiber content of hot air drying was the highest, which was 28.8 g/100 g. Among the effects of different drying methods on physical and chemical indexes of sweet potato leaves, the color and quality of sweet potato leaves powder using freeze drying was obviously better than using hot air drying and microwave drying. The adsorption capacity of cholesterol and unsaturated fatty acids using hot air drying were the highest which were 0.23 mg/mL and 1.54 g/g, respectively. The optimum hydraulic capacity and glucose adsorption capacity using freeze drying were best which were 7.33 g/g and 12.00 mmol/g, respectively. In terms of antioxidant capacity, the antioxidant capacity of the different determination methods showed freeze drying was the best and hot air drying was the worst. The total reducing power, DPPH. scavenging capacity, .OH scavenging capacity and ABTS+ ^{scavenging rate of freeze-drying} were 83.34, 41.28, 9.17 and 27.21 mg Vc/g, respectively. Conclusion Freeze drying which is most suitable for drying sweet potato leaves.