稳定化方法对米糠过氧化物酶活力和抗氧化活性的影响

研究微波加热、干热和盐酸处理三种方法稳定米糠的效果以及对米糠抗氧化活性的影响.实验结果表明,以过氧化物酶残余活力为指标,微波加热稳定米糠效果最好,其过氧化物酶残余活力为新鲜米糠的0.7％,而干热和盐酸处理的米糠的过氧化物酶残余活力分别为新鲜米糠的1.6％和7.8％.三种方法对米糠多酚类物质和抗氧化活性均造成一定破坏,其中干热稳定、微波稳定和酸化米糠的总酚含量分别为新鲜米糠的98.8％、79.0％和60.4％,它们对DPPH自由基的清除率分别为89.0％、79.4％和63.5％,干热稳定米糠和微波稳定米糠的还原能力和抑制亚油酸过氧化活性均相似,均小于新鲜米糠而大于酸化米糠.提高米糠提取物浓度可有效提高其抗氧化活性.

EFFECTS OF STABILIZING METHODS ON PEROXIDASE ACTIVITY AND ANTIOXIDANT ACTIVITY OF RICE BRAN

Effects of such three methods as microwave heating,oven heating and treatment with HCl on stabilization and antioxidant activity of rice bran were investigated.Results showed that according to the residual peroxidase activity of rice bran,microwave heating was the best method.The residual peroxidase activity of rice bran stabilized by microwave heating was only 0.7% of fresh bran,compared with 1.6% and 7.8% for oven heating bran and acidified bran.Polyphenol content and antioxidant activity of bran were decreased to some extent by stabilization with three methods.The polyphenol content of bran stabilized by oven heating,microwave heating and acidification were 98.8%、79.0% and 60.4% of that of fresh bran,and DPPH radical scavenging rates were 89.0%、79.4% and 63.5% respectively.Rice bran stabilized by microwave heating and oven heating had similar inhibition of linoleic acid peroxidation and reducing power,both lower than fresh bran and higher than acidified bran.The antioxidant activity of rice bran extracts could be increased effectively by increasing the concentration of extracts.