紫花苜蓿叶蛋白抗氧化产物的制备及其抗氧化活性的研究

Study on preparation and antioxidant activity of alfalfa leaf protein antioxidant products

以紫花苜蓿叶蛋白为原料,葡萄糖为改性物,以总还原能力,DPPH·清除率与HO·清除率为指标,湿热美拉德反应为改性方法,在单因素试验基础下探究反应体系pH值、反应底物配比、温度及时间对紫花苜蓿叶蛋白抗氧化活性的影响。结果表明在pH=9,底物配比(m紫花苜蓿叶蛋白∶m葡萄糖)为2∶1,反应温度为80℃,反应时间为60 min时美拉德产物(改性之后的紫花苜蓿叶蛋白)的抗氧化活性最显著。在最优单因素条件下未改性的紫花苜蓿叶蛋白总还原能力为0.84,DPPH·清除率为1.45%,HO·清除率为2.18%。在最优单因素条件下改性之后的紫花苜蓿叶蛋白总还原能力达到1.10,DPPH·清除率达到75.10%,HO·清除率达到39.70%,与未改性的蛋白相比总还原能力提高了0.31,DPPH·清除率提高了50.80%,HO·清除率提高了17.21%。通过测定在不同单因素条件下美拉德产物的褐变程度、中间产物、接枝度等,表明紫花苜蓿叶蛋白与葡萄糖之间发生了美拉德反应。

Using alfalfa leaf protein as raw material,glucose as modifier,total reduction capacity,DPPH free radical scavenging rate and OH free radical scavenging rate as index,and wet-hot Maillard reaction as modification methods,the effects of pH value,substrate ratio,temperature and time on the antioxidant activity of alfalfa leaf protein were explored by single factor experiment.The results showed that the antioxidant activity of Maillard product was the most significant at pH=9,substrate ratio(m-alfalfa leaf protein∶m-glucose)of 2∶1,reaction temperature of 80℃ and reaction time of 60 min.Under the optimum single factor conditions,the total reduction capacity of unmodified alfalfa leaf protein was 0.84,DPPH scavenging rate was 1.45%,HO scavenging rate was 2.18%.Under the optimum single factor conditions,the total reduction capacity of alfalfa leaf protein was 1.10,DPPH scavenging rate was 75.10%,HO scavenging rate was 39.70%.Compared with the single protein,the total reduction power of the modified protein increased by 0.31,the DPPH free radical scavenging rate increased by 50.80%,and the OH freeradical scavenging rate by 17.2%.Maillard reaction between alfalfa leaf protein and glucose was observed by determining the degree of browning,intermediate products and grafting degree of Maillard products under different single factor conditions.