紫甘薯膳食纤维的提取及对自由基的清除作用

Dietary fiber extracation from purple sweet potato and its ability of removing free radicals

以紫甘薯为材料,设计4因素3水平的正交实验,酶法提取膳食纤维.结果表明紫甘薯粉中膳食纤维提取的最佳工艺参数为0.7％的混合酶（其中α-淀粉酶∶糖化酶为6∶1）,酶解温度70℃,处理时间80 min,0.6％蛋白酶.以体外实验研究不同质量浓度（20～140 mg/mL）的膳食纤维鲜样对1,1—二苯基—2—苦味酰基自由基（DPPH）、超氧阴离子自由基（O2^-·）、羟自由基（·OH）的清除效果.结果表明紫薯膳食纤维对DPPH O2^-·、·OH都有明显的清除效果,在20～140 mg/mL的膳食纤维的浓度范围内,其清除自由基的效果随着膳食纤维的浓度增大而增强,但当浓度增加到一定程度后,对DPPH、超氧阴离子自由基的清除能力趋于平缓,对·OH的清除效果呈直线上升;其清除能力顺序为：DPPH自由基＞超氧阴离子自由基＞羟自由基.

The dietary fiber was extracted from fresh purple sweet potato by enzymatic hydrolysis and tested by orthogonal experiment.The results indicated that the optimal extraction processing conditions were：0.7％ mixed enzyme （α-amylase and glucoamylase at the ratio of 6 ∶ 1）,hydrolysis temperature 70 ℃ hydrolysis time 80 min,and 0.6％ protease at 60 ℃ for 60 min.The scavenging effects of fresh dietary fiber with various concentrations（20～140 mg/mL） on DPPH,superoxide anion and hydroxyl free radical were also investigated in vitro.The results showed that the dietary fiber had strong scavenging capability on the 3 kinds of free radicals.With the increase of concentration of dietary fiber,its ability of removing free radicals was strengthened.But within the scope of 20～ 140 mg/mL,when the concentration increases to a certain extent,its ability of removing free radicals begins to flatten out on DPPH and superoxide anion free radical,the hydroxyl radical scavenging ability in a straight line up.With a radical scavenging ability size order as DPPH ＞superoxide anion＞hydroxyl free radical.