Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology & Business University (BTBU), Beijing 100048, China; Glyn O. Phillips Hydrocolloid Research Centre, School of Food and Biological Engineering, Hubei University of Technology, Wuhan 430068, China.
Texture Design Laboratory, San-Ei Gen F.F.I. Inc., 1-1-11, Sanwa-cho, Toyonaka, Osaka 561-8588, Japan.
Food Res Int. 2019 Feb;116:232-240. doi: 10.1016/j.foodres.2018.08.020. Epub 2018 Aug 7.
Previous studies have demonstrated that oligoguluronate (guluronate block extracted from alginate, GB) was an efficient modulator of the gelation and gelling properties of macromolecular alginate in the presence of calcium. Here we report totally different modulatory effects of the oligomer when used to modify the gelation of low methoxyl pectin (LMP). GB was found to promote the gelation of LMP in the range of R ([Ca]/[guluronate + galacturonate]) < 0.25 and could make non-gelling systems gellable. This is significantly different from the case of alginate where no gelation could be induced at all. In the range of 0.25 < R < 0.60, the addition of GB was found to inhibit the gelation of LMP, whereas it had a negligible effect on the gelation of alginate as long as a fixed R was considered. In the range of R > 0.60, GB was found to promote the gelation of LMP again, which is similar to the case of alginate. The results were in consistence with microstructural observations by AFM. The different modulatory effects of GB were thought to arise from the different gelation mechanisms of LMP and alginate, that is, a progressive dotting growth of LMP dimers vs. a critical zippering growth of alginate dimers during Ca-induced crosslinking. The mechanism of GB modulating the gelation of LMP was proposed and compared to that for alginate.
先前的研究表明，寡聚古罗糖醛酸（从褐藻酸钠中提取的古罗糖醛酸嵌段，GB）是一种有效的调节剂，可以在钙离子存在的情况下调节高分子海藻酸钠的凝胶化和凝胶性质。在这里，我们报告了寡聚体在修饰低甲氧基果胶（LMP）凝胶化时完全不同的调节作用。研究发现，GB 可以促进 R（[Ca]/[古罗糖醛酸+半乳糖醛酸]）<0.25 范围内的 LMP 凝胶化，并且可以使非凝胶化体系凝胶化。这与海藻酸钠的情况明显不同，在海藻酸钠中，根本不可能诱导凝胶化。在 0.25<R<0.60 的范围内，发现添加 GB 会抑制 LMP 的凝胶化，而只要考虑到固定的 R，它对海藻酸钠的凝胶化几乎没有影响。在 R>0.60 的范围内，发现 GB 再次促进 LMP 的凝胶化，这与海藻酸钠的情况类似。结果与 AFM 的微观结构观察结果一致。GB 的不同调节作用被认为是由于 LMP 和海藻酸钠的不同凝胶化机制引起的，即 LMP 二聚体的渐进点生长与 Ca 诱导交联过程中海藻酸钠二聚体的关键拉链生长。提出了 GB 调节 LMP 凝胶化的机制，并与海藻酸钠的机制进行了比较。
