南瓜籽蛋白酶解液的超滤分离及其抗氧化活性研究

采用超滤技术分离南瓜籽蛋白酶解液,通过研究操作压力、料液浓度、pH和时间四个因素对膜通量和膜效能的影响,依次得到截留分子量分别为10、4ku两次超滤的最佳工艺条件,并比较超滤前后酶解液的抗氧化活性。结果表明,截留分子量为10ku的超滤膜的操作压力为0.25MPa、料液浓度为3.0%、料液pH为7,操作时间为60min;截留分子量为4ku的超滤膜的操作压力为0.20MPa、料液浓度为2.0%、料液pH为7,操作时间为60min。经过超滤以后分子量小于4ku的组分具有更强的清除自由基的能力,其中清除50%DPPH自由基所需的多肽浓度即半抑制浓度IC50值为2.76mg/mL、清除羟基自由基（·OH）的IC50值为2.91mg/mL、清除超氧阴离子自由基（O2-·）的IC50值为23.58mg/mL,同时对铁离子还具有显著的还原能力,吸光度为0.5时所需的多肽浓度为9.43mg/mL。 

Study on separation of the enzymatic hydrolysates derived from pumpkin seed protein with ultrafiltration technology and its antioxidative activity

Enzymatic hydrolysates derived from pumpkin seed protein was separated through ultrafiltration membranes of which the cut-off molecular weight were 10, 4ku.Optimum conditions of the two separation processes were obtained from the study of the effect of pressure, concentration of hydrolysate, pH and time on ultrafiltration permeate flux and membrane efficiency, and the antioxidant activity of hydrolysates before and after ultrafiltration also was studied.The result showed that the optimum conditions of the cut-off molecular weight of 10ku were pressure 0.25MPa, concentration of hydrolysate 3.0%, pH7 and time 60min.And the optimum conditions of the cut-off molecular weight of 4ku were pressure 0.20MPa, concentration of hydrolysate 2.0%, pH7 and time 60min.After ultrafiltration components with a molecular weight below 4ku had stronger free radical scavenging capacity, and reducing power, the IC 50 value of diphenyl picryl-hydrazyl radical (DPPH.) , hydroxyl radical (.OH) , and superoxide anion radical (O 2.) respectively was 2.76, 2.91, 23.58mg/mL, and the concentration of the components was 9.43mg/mL when the absorbance was 0.5.