School of Food Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, China.
Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky, USA.
J Texture Stud. 2023 Apr;54(2):323-333. doi: 10.1111/jtxs.12743. Epub 2023 Mar 8.
The objective of this study was to investigate the effect of pH-shifting on the textural and microstructural properties of mung bean starch (MBS)-flaxseed protein (FP) composite gels. Results showed that different pH-shifting treatments caused changes in hydrogen bond interactions and secondary structures in composite gels, leading to the formation of loose or compact gel networks. The pH 2-shifting modified protein and starch molecules with shorter chains tended to form smaller intermolecular aggregates, resulting in the formation of a looser gel network. For pH 12-shifting treatment, conformational change of FP caused the unfolding of protein and the exposure of more hydrophobic groups, which enhanced the hydrogen bond and hydrophobic interactions between polymers, contributing to the formation of a compact gel network. Furthermore, pH 12-shifting improved the water-holding capacity (WHC), storage modulus, and strength of gels, while pH 2-treated gels exhibited lower WHC, hardness, and gumminess due to the degradation of MBS and denaturation of FP caused by extreme acid condition. These findings suggest that pH-shifting can alter the gel properties of bi-polymeric starch-protein composite systems by affecting the secondary structures of proteins and the hydrogen bonding between the polymers, and provide a promising way for a wide application of FP in soft gel-type food production.
本研究旨在探讨 pH 值变化对绿豆淀粉（MBS）-亚麻籽蛋白（FP）复合凝胶的质构和微观结构特性的影响。结果表明，不同的 pH 值变化处理导致复合凝胶中氢键相互作用和二级结构发生变化，形成疏松或致密的凝胶网络。pH 2 变化处理使短链的蛋白和淀粉分子改性，更容易形成较小的分子间聚集体，从而形成更疏松的凝胶网络。对于 pH 12 变化处理，FP 的构象变化导致蛋白展开，暴露出更多的疏水基团，增强了聚合物之间的氢键和疏水相互作用，有助于形成致密的凝胶网络。此外，pH 12 变化处理提高了凝胶的持水力（WHC）、储能模量和强度，而 pH 2 处理的凝胶由于极端酸性条件下 MBS 的降解和 FP 的变性，WHC、硬度和胶粘性较低。这些发现表明，pH 值变化可以通过影响蛋白质的二级结构和聚合物之间的氢键来改变双聚合物淀粉-蛋白复合体系的凝胶性质，为 FP 在软凝胶型食品生产中的广泛应用提供了一种有前途的方法。
