We investigate changes in the molecular structures of whey proteins (WPI) caused by heat-induced interaction and reaction with varying concentrations of sugar beet pectin (SBP) in aqueous solution at neutral pH. The resulting complexes were examined using circular dichroism (CD) and steady-state and time-resolved fluorescence spectroscopic techniques. Far-UV CD spectroscopy combined with spectral deconvolution revealed noticeable reduction (up to 5%) in the amount of antiparallel β-sheet element of WPI upon interacting with SBP. Analyses from the UV-VIS and steady-state fluorescence spectroscopies showed changes in the molecular electronic states of both WPI and the feruloyl moieties of SBP upon heat-induced interaction and conjugation. The tertiary structural contacts in WPI, studied by the intrinsic Trp fluorescence, were also disrupted in the presence of SBP in the form of FRET (Fluorescence Resonance Energy Transfer) complexes, most noticeably at a high level of SBP (3%), contrasting to the results from dry-heating. The thermal stability of WPI, at both secondary and tertiary structural levels, did not increase considerably by interacting and conjugating with SBP, especially at an equal concentration of SBP (3%). However, the stability of feruloyl groups of SBP saw moderate improvement and was less pronounced than that of the dry-state reactions.

我们调查在中性pH值下，水溶液中不同浓度的甜菜果胶（SBP）的热诱导的相互作用和反应引起的乳清蛋白（WPI）分子结构的变化。使用圆二色性（CD）以及稳态和时间分辨荧光光谱技术检查所得复合物。远紫外CD光谱结合光谱去卷积显示，与SBP相互作用后，WPI的反平行β-折叠元素的数量显着减少（最多5％）。从UV-VIS和稳态荧光光谱学分析表明，在热诱导的相互作用和结合后，WPI和SBP的阿魏酰基部分的分子电子态均发生了变化。通过固有Trp荧光研究了WPI中的三级结构接触，在SBP形式的FRET（荧光共振能量转移）复合物的存在下，它们的破坏也被破坏了，最明显的是在SBP的高水平（3％）下，与干热的结果相反。通过与SBP相互作用和结合，WPI在二级和三级结构水平上的热稳定性都没有显着提高，尤其是在等浓度的SBP（3％）下。但是，SBP的阿魏酰基基团的稳定性得到中等程度的改善，并且比干态反应的稳定性不那么明显。通过与SBP相互作用和结合而不会显着增加，特别是在SBP浓度相同（3％）的情况下。但是，SBP的阿魏酰基基团的稳定性得到中等程度的改善，并且不如干态反应明显。通过与SBP相互作用和结合而不会显着增加，特别是在SBP浓度相同（3％）的情况下。但是，SBP的阿魏酰基基团的稳定性得到中等程度的改善，并且不如干态反应明显。