Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
Int J Biol Macromol. 2013 Nov;62:387-96. doi: 10.1016/j.ijbiomac.2013.09.029. Epub 2013 Oct 1.
In this present study, an efficient complex enzyme-assisted extraction technology was developed and optimized to extract polysaccharides from alfalfa using four factors at five levels central composite rotatable response surface design (CCRD). The experimental data was fitted to a second order polynomial equation with high coefficient of determination values (R(2)>0.95). The results of statistical analysis showed that the linear and quadratic terms of these four variables had significant effects (P<0.05) on the yield of polysaccharides from alfalfa. The optimum conditions were as follows: enzyme concentration of 2.5%, 2.0%, 3.0% (weight of alfalfa) of cellulase, papain and pectase, extraction temperature 52.7 °C, extraction pH 3.87, ratio of water to raw material 78.92 mL/g and extraction time 2.73 h. Under the optimal conditions, the experimental extraction yield of alfalfa polysaccharides was 5.05 ± 0.02%, which was well matched with the value (5.09%) predicted by the CCRD model. Moreover, evaluation of the antioxidant activity of polysaccharides from alfalfa in vitro suggested that the polysaccharides had good antioxidant effect, especially scavenging activity for hydroxyl radical and DPPH radical, which indicated that the polysaccharides from alfalfa may be explored as a novel natural antioxidant.
在本研究中，采用四因素五水平的中心复合旋转响应面设计（CCRD）开发并优化了一种从紫花苜蓿中提取多糖的高效复合酶辅助提取技术。实验数据拟合到二次多项式方程，具有较高的决定系数值（R²>0.95）。统计分析结果表明，这四个变量的线性和二次项对紫花苜蓿多糖的得率有显著影响（P<0.05）。最佳条件如下：纤维素酶、木瓜蛋白酶和果胶酶的酶浓度分别为 2.5%、2.0%和 3.0%（紫花苜蓿重量的百分比），提取温度为 52.7°C，提取 pH 值为 3.87，水与原料的比例为 78.92 mL/g，提取时间为 2.73 h。在最佳条件下，紫花苜蓿多糖的实验提取率为 5.05±0.02%，与 CCRD 模型预测值（5.09%）吻合较好。此外，体外评价紫花苜蓿多糖的抗氧化活性表明，多糖具有良好的抗氧化作用，特别是对羟基自由基和 DPPH 自由基的清除活性，这表明紫花苜蓿多糖可能作为一种新型天然抗氧化剂进行探索。
