陕北狗头红枣可溶性膳食纤维提取工艺优化及其理化特性与抗氧化活性研究

Study on extraction process optimization,physicochemical properties and antioxidant activity of soluble dietary fiber from goutou jujube in Northern Shaanxi

膳食纤维(Dietary Fiber,DF)具有多种生理活性功能,应用前景广阔,其中水溶性膳食纤维(Soluble Dietary Fiber,SDF)功能优于水不溶性膳食纤维(Insoluble Dietary Fiber,IDF).为提高陕北狗头红枣SDF得率,采用超声波-酶耦合法,在单因素试验基础上通过响应面优化提取工艺,并对提取的红枣SDF的结构表征、理化性质及抗氧化特性进行分析.结果显示,最佳提取工艺关键参数为纤维素酶添加量1 300 U/g,酶解pH 7.0,酶解温度60℃,超声功率100 W,此条件下红枣SDF得率为21.37±0.35%.红枣SDF的持水力为4.8±0.8 g/g、持油力为1.48±0.1 g/g、膨胀力为2.3±0.1 mL/g、阳离子交换能力为1.23±0.1 mmol/g、葡萄糖吸附率为16.8±0.15 mmol/g、胆固醇吸附率为8.12±0.18 mg/g(pH=2)和10.35±0.19 mg/g(pH=7).红枣SDF具有类似蜂巢的疏松多孔网状结构特征,推测含有糖类、木聚糖、半纤维素、纤维素、木质素等成分,符合膳食纤维结构特征.红枣SDF在1~7 mg/mL范围内,抗氧化活性与浓度正相关,DPPH和ABTS自由基清除率均达到90%以上.研究结果提高了红枣SDF得率,并揭示红枣SDF具有较好的理化性质及抗氧化活性,为陕北狗头红枣膳食纤维制备和产业化应用提供了参考.

Dietary Fiber(DF) has a variety of physiological functions and has broad application prospects.The function of soluble dietary fiber(SDF) is better than that of insoluble dietary fiber(IDF).In order to improve the yield of SDF from goutou jujube in Northern Shaanxi,the ultrasonic-enzyme coupled method was used to optimize the extraction process based on single factor test combined with response surface methodology.The structure characterization,physicochemical properties and antioxidant properties of SDF were analyzed.The results showed that the key parameters of the optimal extraction process were as follows:cellulase dosage of 1 300 U/g,enzymolysis pH of 7.0,enzymolysis temperature of 60 ℃ and ultrasonic power of 100 W.Under these conditions,the yield of SDF was 21.37±0.35%.The water holding capacity of SDF was 4.8±0.8 g/g,oil holding capacity was 1.48±0.1 g/g,swelling capacity was 2.3±0.1 mL/g,cation exchange capacity was 1.23±0.1 mmol/g,glucose adsorption rate was 16.8±0.15 mmol/g,cholesterol adsorption rate was 8.12±0.18 mg/g(pH=2) and 10.35 ± 0.19 mg/g(pH=7).It was found that SDFo f jujube had a loose porous network structure similar to that of honeycomb,and it was speculated that it contained carbohydrates,xylan,hemicellulose,cellulose,lignin and other components.The antioxidant activity was positively correlated with the concentration of SDF in the range of 1~7 mg/mL,and the DPPH and ABTS free radical scavenging rates were more than 90%.The results showed that jujube SDF had good physical and chemical properties and antioxidant activity,which provided a reference for the preparation and industrial application of dietary fiber of jujube from Northern Shaanxi.