Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, Canada L2S 3A1.
Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, Canada L2S 3A1.
Food Chem. 2011 Aug 1;127(3):1023-30. doi: 10.1016/j.foodchem.2011.01.075. Epub 2011 Jan 26.
Size-exclusion chromatography (SEC) and activity-guided fractionation of honeys allowed the isolation of high molecular weight brown compounds, ranging in size from 66 to 235kDa that exhibited peroxyl radical-scavenging activity. Their concentrations, antioxidant activity and degree of browning increased after heat-treatment of honeys, suggesting that they represent melanoidins. Chemical analysis of melanoidins demonstrated the presence of proteins, polyphenols and oligosaccharides. Heat-treatment caused an increased incorporation of phenolics into high molecular weight melanoidins and drastically decreased the protein content in these fractions with a concomitant appearance of high molecular weight protein-polyphenol complexes of reduced solubility. LC-ESI-MS demonstrated the presence of oligosaccharide moieties, supporting the postulated origin of melanoidins. The changes in the phenolic content of melanoidins from heated honeys were strongly correlated with their oxygen radical absorbance capacity (ORAC) values (R=0.75, p<0.0001), indicating that polyphenols contribute to the antioxidant activity of melanoidins. In summary, honey melanoidins are multi-component polymers consisting of protein-polyphenol-oligosaccharide complexes. A direct interaction between polyphenols and melanoidins resulted in a loss or gain of function for melanoidin antioxidant activity.
采用排阻色谱（SEC）和活性导向分离法对蜂蜜进行分离，得到了具有清除过氧自由基活性的高分子量棕色化合物，其分子量大小分布在 66 至 235kDa 之间。这些化合物的浓度、抗氧化活性和褐变程度在蜂蜜热处理后增加，表明它们代表了类黑精。类黑精的化学分析表明，它们含有蛋白质、多酚和低聚糖。热处理导致酚类物质更多地结合到高分子量的类黑精中，同时这些部分的蛋白质含量急剧下降，伴随出现的是高分子量、低溶解度的蛋白质-多酚复合物。LC-ESI-MS 表明存在寡糖部分，支持了类黑精的假定来源。热处理蜂蜜中类黑精的酚类物质含量的变化与它们的氧自由基吸收能力（ORAC）值呈强相关性（R=0.75，p<0.0001），表明多酚类物质对类黑精的抗氧化活性有贡献。总之，蜂蜜类黑精是由蛋白质-多酚-低聚糖复合物组成的多组分聚合物。多酚类物质与类黑精的直接相互作用导致了类黑精抗氧化活性的丧失或获得。
