干燥方式对香蕉片总多酚含量及其抗氧化性的影响

Effects of Different Drying Methods on the Content and Antioxidant Activity of Total Polyphenol from Banana Slices

目的:比较热风干燥、真空干燥、真空冷冻干燥对香蕉片中总多酚含量及其抗氧化活性的影响。方法:采用福林酚比色法分别测定3种干燥方式下的香蕉片的总酚含量,并比较其1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力、羟自由基(OH)清除能力、超氧阴离子自由基(O2-)清除能力和还原能力(FRAP法)。结果:真空冷冻干燥、真空干燥、热风干燥后香蕉片的总酚含量分别为2.33、7.16、2.68mg/g;DPPH自由基清除能力和·OH清除能力大小依次为真空冷冻干燥>真空干燥>热风干燥;O2-清除能力为热风干燥最弱,在低质量浓度时为真空冷冻干燥最强,较高质量浓度时为真空干燥最强;还原能力为真空冷冻干燥最强,真空干燥与热风干燥无明显差异。结论:经过综合比较发现,3种干燥方式中真空冷冻干燥对香蕉片总多酚含量及其抗氧化性影响最小。

Objective： To compare the effects of hot-air drying, vacuum drying and vacuum freeze drying on total polyphenol content in banana slices and its antioxidant activity. Methods： Banana slices were dried by hot-air drying, vacuum drying and vacuum freeze drying, respectively. The content of total polyphenol was determined by Folin-Ciocalteu method. The DPPH, hydroxyl, superoxide anion radical scavenging capacities and total reducing power of total polyphenols in dried banana slices were determined and compared. Results： The contents of total polyphenol in banana slices dried by freeze drying, vacuum drying and hot-air drying were 2.33, 7.16 mg/g and 2.68 mg/g, respectively. The DPPH and hydroxyl scavenging capacities of total polyphenols from banana slices dried by different methods followed the decreasing order： vacuum freeze drying 〉 vacuum drying 〉 hot air drying. The superoxide anion radical scavenging capacity of total polyphenol from hot air dried banana slices was the lowest, those from freeze dried banana slices had the highest capacity at lower concentration and those from vacuum dried banana slices had the highest capacity at higher concentration. The reducing power of total polyphenol from vacuum freeze dried banana slices was also superior to that of those obtained from the other two methods, and no significant difference between vacuum drying and hot air drying was observed. Conclusion： Compared with hot-air drying and vacuum drying, freeze drying has less influence on the content of total polyphenol and the antioxidant activity of the extracted total polyphenol from banana slices.