[关键词]
[摘要]
研究了在湿热条件下可食性有机酸(琥珀酸)对降解小麦面筋蛋白脱酰胺作用的特征。通过对改性小麦面筋蛋白(SDWG)的脱酰胺作用程度、氮溶指数、水解度等理化指标,以及热特性、分子量分布、蛋白质的二级结构表征湿热处理过程中SDWG分子聚集态变化特征。结果显示改性过程中小麦面筋蛋白分子的降解反应呈明显阶段性,在前10 min,当脱酰胺程度(从24.65%到64.79%),氮溶指数(从11.55%到91.31%),玻璃态转变温度(从50.70 ℃到61.80 ℃)和反应热焓[从1.73 J/(g?K)到2.35 J/(g?K)]均明显增加,但是小麦面筋蛋白水解度增加幅度仅小于1%,且SDS-PAGE和SE-HPLC检测到SDWG总体呈降解的反应趋势,然而红外光谱表示SDWG的分子柔性总体下降,特别反应第6 min,分子质量分布以及二级结构特征均呈现明显的改变。该数据表明在湿热条件下琥珀酸对小麦面筋蛋白的脱酰胺作用具有较高特异性,而小麦面筋蛋白解离特征呈现逐步降解和分阶段性。
[Key word]
[Abstract]
The aim of this study was to investigate the characteristics of the degradation of wheat gluten by deamidation using carboxylic acids (succinic acid). The changes in succinic acid deamidated wheat gluten (SDWG), during hydrothermal treatment, were characterized using physicochemical indexes such as the deamidation degree (DD), nitrogen soluble index (NSI), degree of hydrolysis (DH), thermal characteristics, molecular weight distribution (MWD), and secondary conformation of proteins. The results indicated that, during modification, the degradation of wheat gluten molecules occurred in a stepwise manner. During the first 10 mins, the DD (from 24.65% to 64.79%), NSI (from 11.55% to 91.31%), glass transition temperature (from 50.70 to 61.80 ℃), and enthalpy [from 1.73 to 2.35 J/(g?K)] all significantly increased, while the increase of DH was less than 1%. Additionally, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion-high-performance liquid chromatography (SE-HPLC) showed that SDWG had a tendency to degrade; infrared spectra indicated that the flexibility of SDWG generally decreased. In particular, significant changes in MWD and secondary conformation were observed at 6 min after the reaction started. These results indicate that succinic acid has a high specificity for the deamidation of wheat gluten upon hydrothermal treatment and that the degradation of wheat gluten is a stepwise process with different stages.
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[基金项目]
国家自然科学青年基金项目资助(31201287)