莲藕多糖的碱法提取工艺优化与抗氧化活性评价

Optimization of alkaline extraction technology and evaluation of antioxidant activity of Nelumbo nucifera Gaertn. polysaccharide

目的 优化莲藕多糖的碱法提取工艺并评价其抗氧化活性。方法 以多糖提取率为指标,以料液比、NaOH浓度、提取时间和提取温度为考察因素进行单因素实验,结合响应面法对提取工艺进行优化,并分析所得莲藕多糖的纯度、相对分子质量和自由基清除能力。结果 响应面优化结果显示,除料液比以外,NaOH浓度、提取时间和提取温度对莲藕多糖提取率均具有显著影响(P<0.05)。确定最佳工艺条件为:料液比1:16(g/mL)、NaOH浓度0.04 mol/L、提取时间1.3 h、提取温度57℃,此条件下的多糖提取率达13.07%,与预测值13.52%相近。该碱法提取多糖的纯度达73.66%,平均相对分子质量为1.727×10^(5)Da。抗氧化活性评价结果显示,莲藕多糖具有清除1,1-二苯基-2-三硝基苯自由基和羟基自由基的能力,且清除率与多糖浓度成正比。结论 优化了碱提莲藕多糖的提取工艺,且提取得到的多糖具有较好的抗氧化活性,为莲藕资源的开发利用提供了理论依据。

Objective To optimize the alkaline extraction technology of Nelumbo nucifera Gaertn. polysaccharide and evaluate its antioxidant activity. Methods The extraction rate of polysaccharide was taken as the index,the single factor experiment was carried out with the ratio of solid to liquid,NaOH concentration,extraction time and extraction temperature as the factors. The response surface methodology was used to optimize the extraction process,and the purity,molecular weight and free radical scavenging ability of the obtained Nelumbo nucifera Gaertn. polysaccharide were analyzed. Results The results of response surface optimization showed that NaOH concentration,extraction time and extraction temperature had significant effects on the extraction yield of polysaccharides(P<0.05) except for ratio of solid to liquid. The optimal extraction conditions were as follows: The solid-liquid ratio of 1:16(g/mL),the NaOH concentration 0.04 mol/L,the extraction time of 1.3 h and the extraction temperature of 57℃. Under these conditions,the extraction rate of polysaccharide was the highest,up to 13.07%,which was close to the predicted value of 13.52%. The purity of the polysaccharide extracted by the alkali method reached 73.66%,and the average relative molecular mass was 1.727×10^(5) Da. The results of antioxidant activity evaluation showed that Nelumbo nucifera Gaertn. polysaccharide had the ability to scavenge 1,1-diphenyl-2-picryhydrazyl radical and hydroxyl radical,and the ability to scavenging rate was proportional to the concentration of polysaccharide. Conclusion The extraction process of Nelumbo nucifera Gaertn. polysaccharides is optimized,and it has good antioxidant activity,which provides a theoretical basis for the development and utilization of Nelumbo nucifera Gaertn. resources.