富含 Ca 和 β 酪蛋白的酪蛋白胶束的结构和成分表征,Food Hydrocolloids

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富含 Ca 和 β 酪蛋白的酪蛋白胶束的结构和成分表征
Food Hydrocolloids ( IF 11.0 ) Pub Date : 2024-01-23 , DOI: 10.1016/j.foodhyd.2024.109811
Thea Lykkegaard Møller , Søren Bang Nielsen , Jan Skov Pedersen , Milena Corredig

人们对了解改变酪蛋白胶束组成甚至创造它们的潜力越来越感兴趣。在这项研究中，通过从天然酪蛋白胶束中解离产生可溶性酪蛋白级分，并在将其添加到天然酪蛋白胶束后单独研究它们的特性。通过小角 X 射线散射 (SAXS) 研究这些富集酪蛋白胶束的结构，以评估富集是否导致其内部结构发生变化。天然酪蛋白胶束从 pH 6.8 酸化至 5.6 导致胶体磷酸钙解离，SAXS 数据显示强度在 = 0.08 Å 处下降，其中是散射矢量的模量。此外，天然酪蛋白胶束的酸化（pH 6.0）和在 4 °C 下的孵育导致中间区域（0.01-0.02 Å）的散射强度降低，这表明酪蛋白胶束中中间结构元素之间异质性的丧失。这种变化是由磷酸钙的胶束溶解和 4°C 下 β-酪蛋白的释放引起的。用富含 β-酪蛋白的血清重新悬浮酪蛋白胶束后，可溶性 β-酪蛋白的缺失表明大多数 β-酪蛋白在胶体部分中重新结合。SAXS 探测到的这些样品的结构特征没有变化。这项工作带来了新的证据，表明虽然小程度的解离可能会影响酪蛋白胶束的结构，但β-酪蛋白的富集会产生与天然胶束相似的结构。

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Structural and compositional characterization of Ca- and β-casein enriched casein micelles

There is an increased interest in understanding the potential of modifying casein micelles composition, or even creating them . In this study, soluble casein fractions were created by dissociation from native casein micelles, and their properties were studied in isolation, and after their addition to native casein micelles. The structure of these enriched casein micelles was investigated by small-angle X-ray scattering (SAXS) to evaluate if the enrichment caused changes in their internal structure. Acidification of native casein micelles from pH 6.8 to 5.6 caused colloidal calcium phosphate dissociation, and SAXS data showed a decrease in intensity at = 0.08 Å, where is the modulus of the scattering vector. Additionally, the acidification of native casein micelles (to pH 6.0) and incubation at 4 °C caused a decrease in scattering intensity at the intermediate region (0.01–0.02 Å), signifying a loss of heterogeneity among the intermediate structure elements in the casein micelle. This change was caused by micellar dissolution of calcium phosphate and the release of β-casein at 4 °C. After the resuspension of casein micelles with a β-casein enriched serum, the absence of soluble β-casein suggested that most β-casein was re-associated in the colloidal fraction. These samples showed no changes in the structural features probed by SAXS. The work brings new evidence that, while a small extent of dissociation may affect the structure of the casein micelles, the enrichment with β-casein results in similar structures as those of the native micelle.

更新日期：2024-01-23

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