紫甘薯膳食纤维的提取及对自由基的清除作用

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80min,0.6%蛋白酶。以体外实验研究不同质量浓度(20~140mg/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(O-2·)、羟自由基(·OH)的清除效果。结果表明紫薯膳食纤维对DPPH O-2·、·OH都有明显的清除效果,在20~140mg/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。

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

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.