淡色啤酒类黑精的分离及抗氧化活性评价

Separation and Antioxidant Activity Evaluation of Melanoidins from Lager Beer

摘要:

本文采用超滤结合大孔吸附树脂分离啤酒中的类黑精，并采用ABTS自由基阳离子清除活性和还原力评价其抗氧化活性。研究结果表明：大分子超滤组分（>10 ku）得率和类黑精含量低，抗氧化活性弱，而小分子超滤组分（<10 ku）呈现出分子量越小，得率、类黑精含量和抗氧化活性越高的趋势，其中分子量<3 ku的UF4组分得率、类黑精含量和抗氧化活性均最高。UF4组分经大孔吸附树脂富集后洗脱为三个不同极性组分（D1>D2>D3），其中D1组分得率最高，约占UF4的94%，虽然D3组分得率不足1%，但其类黑精相对含量最高。D2组分ABTS清除活性和还原能力均最高，而D1组分抗氧化活性极弱。因此，啤酒中抗氧化活性最高的类黑精主要集中在分子量小于3 ku的组分中，经大孔树脂层析后，20%乙醇洗脱部分具有最强的抗氧化活性。

Abstract:

The antioxidant activity of melanoidins isolated from beer by ultrafiltration and macroporous resin chromatography was evaluated by measuring their 2,2‘-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and reducing power. The results showed that fraction with high molecular weight (>10 ku) exhibited low yield and melanoidins content as well as weak antioxidant activity, while the lower molecular weight of fractions possessed the higher yield, melanoidins content and antioxidant activity. The UF4 fraction (<3 ku) had the highest yield, melanoidins content and antioxidant activity. The UF4 fraction was separated into 3 fractions with different polarity (D1>D2>D3) by macroporous resin chromatography. The D1 fraction which had the highest yield accounted for almost 94% of the UF4, while the D3 fraction represented less than 1% but showed the highest melanoidins content. The D2 fraction had the strongest ABTS radical scavenging activity and reducing power, whereas D1 showed very weak antioxidant activity. Therefore, the present results indicated that melanoidins with the strongest antioxidant activity existed in UF4 fraction (<3 ku), and could be isolated from beer by macroporous resin chromatography with 20% ethanol elution.