草鱼肌原纤维蛋白-葡萄糖糖基化产物的理化特性及乳化特性研究

Chemical Characterization and Emulsifying Properties of Grass Carp Myofibrillar Protein Glycated with Glucose

选取葡萄糖作为糖基供体对草鱼肌原纤维蛋白进行糖基化修饰,探讨糖基化产物理化性质及其乳化性能。草鱼肌原纤维蛋白与葡萄糖按质量比1∶2混合,在相对湿度为44%、50℃条件下进行糖基化反应,测定产物的糠氨酸含量、荧光强度、游离氨基含量、蛋白质二级结构以及乳化性和乳化稳定性。结果表明:随着加热时间的延长,糠氨酸含量和荧光强度呈现先增大后降低的趋势,游离氨基含量和褐变强度ΔE持续增加(p<0.05),其中在反应48 h时,糠氨酸含量达到最大值((4.09±0.07)mg/100 mg样品);二级结构分析表明,糖基化对草鱼肌原纤维蛋白的二级结构影响较小。此外,糖基化修饰显著提高了草鱼肌原纤维蛋白的乳化性能(p<0.05),且经过48 h制备的糖基化产物的乳化活性及乳化稳定性最高,分别为未反应草鱼肌原纤维蛋白的1.32倍(p<0.05)和1.53倍(p<0.05)。进一步通过相关性分析发现,草鱼肌原纤维蛋白的乳化性受糖基化反应程度的影响。

Glucose was used as a glycosyl donor to glycosylate the grass carp myofibrillar protein to investigate the physicochemical properties and emulsifying properties of glycosylation production. The reaction products of grass carp myofibrillar protein and glucose mixture（ 1∶ 2,w/w） were prepared by dry-heating at 50 ℃ and 44% relative humidity,and the content of furosine,free amino group,fluorescence intensity and secondary structure,and emulsifying property and emulsifying stability of the conjugates were further analyzed.Results showed that,as dry-heating time was prolonged,the content of furosine and the fluorescence intensity firstly increased and then decreased; and the total colour difference（ ΔE） increased（ p〈0.05）,and for 48 h of dry-heating,the content of furosine reached the maximum（（ 4.09 ± 0.07） mg/100 mg）. Structural analyses suggested that glycosylation had little effects on the secondary structure of myofibrillar protein. Moreover,the glycation significantly improved the emulsifying activity（ EAI） and emulsifying stability（ ESI） of grass carp myofibrillar protein（ p〈0.05）,and the conjugates prepared from 48 h of dry-heating showed the highest ability of EAI and ESI,which was 1.32 and1.53 times of original grass carp myofibrillar protein,respectively.Furthermore,the extent of glycation clearly affected the ability of EAI and ESI of grass carp myofibrillar protein based on the correlation analysis.