香蕉茎秆单宁酸提取纯化及其抗氧化性

Extraction and Purification of Tannins from Banana Pseudostem and Its Antioxidant Properties

以香蕉茎秆为原料,采用溶剂提取法进行单宁酸提取,在单因素试验设计的基础上,通过正交试验优化香蕉茎秆单宁酸提取工艺,采用大孔树脂吸附技术对粗提物进行分离纯化。纯化物采用傅里叶红外光谱（FTIR）测定其官能团,通过凝胶渗透色谱（GPC）测定纯化物的分子量及分子量分布。通过测定其清除1,1-二苯基-2-三硝基苯肼（DPPH）自由基的能力,考察香蕉茎秆单宁酸的抗氧化性。结果表明：香蕉茎秆单宁酸最佳提取工艺为：乙醇浓度50%,提取时间90 min,料液比1∶11,提取温度50℃,在此条件下单宁酸提取量为17.9 mg/g。纯化工艺为：5 mg/m L上样,流速为1.5 m L/min过AB-8型大孔树脂柱,最后用60%乙醇洗脱。FTIR结果表明,该纯化物为多羟基酚酯类化合物;GPC结果显示香蕉茎秆单宁酸分子质量在3.43×10^4~4.43×10^4之间。经过DPPH法测出样品浓度达到0.6 mg/m L时,其DPPH自由基清除率为86.59%。

In this paper, tannins were extracted from banana pseudostem by solvent the extraction method. On the basis of single factor experiment design, the banana pseudostem tannins extraction process was optimized by the orthogonal test. The extracts were purified by macroporous resin adsorption. The purified samples were characterized by Fourier transform infrared spectroscopy （FTIR） and Gel Permeation Chromatography （GPC）. The antioxidant properties of the banana pseudostem tannins were measured by their capacity of clearing free radical of DPPH. The results showed that the optimized condition were the ethanol concentration 50 wt.%, the extraction time 90 min, solid- liquid ratio 1：11, the extracting temperature 50 ~C. Under this condition, the highest amount of extraction of banana pseudostem tannins was 17.9 mg/g. The purification process indicated that the sampling concentration was 5 mg/ml, and the current speed was 1.5 ml/min through macroporous resin column AB-8, and finally eluted with 60 wt.% ethanol solution. FTIR results indicated that the purified banana pseudostem tannins was a muhi-hydroxy phenolic exter compound. The GPC results showed that the molecular weight of the banana pseudostem tannins was between 3.43×10^4--4.43×10^4. The DPPH free radical scavening rate was 86.59% when the concentration of sample was 0.6 mg/mL.