College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, Gansu, People's Republic of China.
College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, Gansu, People's Republic of China.
Food Res Int. 2023 Jan;163:112220. doi: 10.1016/j.foodres.2022.112220. Epub 2022 Nov 24.
pH-responsive in situ gelling properties of thiolated citrus high-methoxyl pectin (TCHMP) were investigated in this study. The gelation capacity results revealed that the in situ gelation behavior of TCHMP only occurred when the pH value was higher than 6.25. The gel strength increased from 26.63 g to 42.77 g as the pH value increased from 7.4 to 8.9. Rheological measurements confirmed that the apparent viscosity and viscoelasticity of TCHMP were highly dependent on pH value and dialysis time. Compared with the control group, the apparent viscosity of TCHMP dialyzed in phosphate-buffered saline (PBS) of pH 8.9 for 180 min increased 695-fold. During the dialysis process of TCHMP at different pH values (7.4-8.9), the final thiol groups content decreased and the final disulfide bonds content increased with the increase in pH value. This illustrates that the mechanism of in situ gelation is mainly the oxidation of thiol-thiol groups to form disulfide bonds. These results can put forward new insights into the pH-responsive in situ gelling properties of TCHMP and provide a theoretical basis for the application of TCHMP in neutral and alkaline gel systems.
本研究考察了巯基化柑橘高甲氧基果胶（TCHMP）的 pH 响应原位凝胶特性。凝胶形成能力的结果表明，TCHMP 的原位凝胶化行为仅在 pH 值高于 6.25 时发生。当 pH 值从 7.4 增加到 8.9 时，凝胶强度从 26.63 g 增加到 42.77 g。流变学测量证实，TCHMP 的表观粘度和粘弹性高度依赖于 pH 值和透析时间。与对照组相比，在 pH 值为 8.9 的磷酸盐缓冲盐水（PBS）中透析 180 分钟的 TCHMP 的表观粘度增加了 695 倍。在不同 pH 值（7.4-8.9）下对 TCHMP 进行透析的过程中，随着 pH 值的升高，最终巯基含量减少，最终二硫键含量增加。这表明原位凝胶化的机制主要是巯基-巯基基团的氧化形成二硫键。这些结果可以为 TCHMP 的 pH 响应原位凝胶特性提供新的见解，并为 TCHMP 在中性和碱性凝胶系统中的应用提供理论基础。
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