Rheological properties in fatty acid salt-induced p-lactoglobulin gel and the changes of secondary structure during the gelation

在本研究中，我们发现β-乳球蛋白（P-LG）的透明凝胶仅通过在室温下向蛋白质溶液中添加脂肪酸盐（FAS）（如癸酸钠）形成。通过动态粘弹性分析研究了FAS诱导凝胶的流变学性质。此外，我们分析了在凝胶化过程中的蛋白质的二级结构的变化，通过傅立叶变换红外光谱（FT-IR）。在β-LG蛋白中，当β-折叠占主导地位时，随着β-折叠含量的减少，分子间β-折叠带逐渐增多。FAS诱导的凝胶形成后，在80℃下加热30 min，观察到热处理使分子间β折叠带明显增加。这些结果表明，FAS诱导的β-LG凝胶形成的蛋白质构象变化比热诱导凝胶中的蛋白质构象变化小。

In this study, we found that transparent gels of β-lactoglobulin (P-LG) were formed only by the addition of fatty acid salts (FAS), such as sodium caprate, to the protein solutions at ambient temperature. We investigated the Theological properties of the FAS-induced gel by the analyses of dynamic viscoelasticity. Furthermore we analysed the changes in the secondary structure of proteins during the gelation step by Fourier transform infrared (FT-IR) spectroscopy. In β-LG protein in which the original contents are predominant β-sheet, intermolecular β-sheet bands increased with the decrease in the content of intramolecular β-sheet. FAS-induced gel was heated at 80℃ for 30 min after the gel was formed, and much increment of the intermolecular β-sheet bands by heat treatment was observed. These results suggest that the formation of FAS-induced gels of β-LG were accompanied by less marked changes in the protein conformation than those in heat-induced gels.