L-赖氨酸与3种还原糖美拉德反应产物的理化特性及抗氧化活性

Physico-chemical Properties and Antioxidant Activity of Maillard Reaction Products from L-lysine and Reducing Sugar Model System

研究还原糖种类和反应时间对美拉德反应产物(Maillard reaction products,MRPs)理化特性和抗氧化活性的影响,采用L-赖氨酸与3种还原糖(D-葡萄糖、D-果糖、D-半乳糖)按浓度比1:1、95℃加热条件进行反应,分别得到0～6h的MRPs,测定MRPs的pH值、吸光度(A294nm和A420nm)、荧光强度、游离氨基含量以及还原能力和ABTS+.清除能力。结果表明:随着加热时间的延长,3个体系的pH值逐渐降低(P<0.05);无荧光中间产物(A294nm)和褐变产物(A420nm)显著增加(P<0.05);荧光强度在加热开始1h内急剧增加随后减小(P<0.05);游离氨基的含量逐渐降低(P<0.05);同时,MRPs的还原能力和ABTS+.清除活性显著增加(P<0.05)。在3种反应体系中,L-赖氨酸与D-半乳糖反应产生的MRPs具有最多的中间产物和最大程度的褐变,以及最强的还原能力和ABTS+.清除能力。由于L-赖氨酸与还原糖反应产生的MRPs具有一定的抗氧化活性和自由基清除能力,所以可以作为一种有效的抗氧化剂应用于食品工业中。

In this study, the effect of reducing sugar type and reaction time on physicochemical properties and antioxidant activity of Maillard reaction products （MRPs） prepared by heating the mixture of L-lysine and reducing sugars （D-glucose, D-fructose and D-galactose） at the molar ratio of 1：1 for 0--6 h in 95 ℃ water bath was investigated. The pH, absorbance （A294nm and A420nm）, fluorescence intensity, free amino group content, reducing power and ABTS＋ scavenging activity of MRPs were also determined. The results showed that as the increase of heating time, the pH of the model system revealed a significant decrease （P〈0.05）; non-fluorescent intermediate products （A294nm） and browning products （A420nm） revealed a significant increase （P〈0.05）; fluorescence intensity revealed a sharp increase within 1 h and a subsequent decrease （P〈0.05）; free amino group content exhibited a gradual decrease （P〈0.05）; and the antioxidant activity of MRPs revealed a significant increase （P〈0.05） evaluated by reducing power and ABTS＋ scavenging activity. MRPs derived from L-lysine and D-galactose model system provided the largest amount of intermediate and browning products, and also possessed higher reducing power and ABTS radical scavenging activity among three systems. Because of its antioxidant activity and radical scavenging activity, MRPs from L-lysine and reducing sugar model system could be a potent antioxidant in food industry.