School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China; Department of Food Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 1088477, Japan.
School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
Carbohydr Polym. 2022 Oct 15;294:119788. doi: 10.1016/j.carbpol.2022.119788. Epub 2022 Jun 28.
The present work investigates the calcium-induced gelation behavior and gel properties of alginate samples of lithium-, sodium-, and potassium-forms. It was found that the effect of the alkali metal counterions varied greatly with the calcium concentration regime, namely, the molar ratio of calcium to guluronate (R = Ca/G). Four different regions were identified, including R < 0.25, 0.25 < R < 0.55, 0.55 < R < 1.0, and R > 1.0. The counterion dependence was interpreted by the relative interaction strength of the monovalent cations with COO groups and their exchange reaction with Ca ions. A mechanistic model depicting the role of counterions was proposed in relation to different steps of the binding and gelation of alginate with calcium. The knowledge gained in the study would further advance the understanding of the gelation mechanism of the industrially important alginate and guide its specific utilizations.
本工作研究了锂、钠、钾形式的藻酸盐样品在钙离子诱导下的凝胶行为和凝胶性质。结果发现，碱金属反离子的作用随钙离子浓度（即钙与古洛糖醛酸的摩尔比 R=Ca/G） regime 变化很大。确定了四个不同的区域，包括 R<0.25、0.25<R<0.55、0.55<R<1.0 和 R>1.0。通过单价阳离子与 COO 基团的相对相互作用强度及其与 Ca 离子的交换反应来解释反离子依赖性。提出了一个描述反离子在藻酸盐与钙离子结合和凝胶化不同步骤中作用的机理模型。该研究获得的知识将进一步加深对工业上重要的藻酸盐凝胶化机制的理解，并指导其特定应用。
