Wu Chun-Lin, Liao Jin-Song, Wang Jin-Mei, Qi Jun-Ru
National Engineering Research Center of Wheat and Corn Further Processing, School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China.
School of Life Sciences, South China Normal University, Guangzhou 510640, PR China; Lemon (Guangzhou City) Biotechnology Co. Ltd., Guangzhou 510640, PR China.
Int J Biol Macromol. 2024 Jun;271(Pt 1):132261. doi: 10.1016/j.ijbiomac.2024.132261. Epub 2024 May 12.
Co-solutes such as sucrose and sugar alcohol play a significant part in low methoxyl pectin (LMP) gelation. To explore their gelation mechanism, we investigated the gelation behavior of LMP in the presence of erythritol and sucrose with Ca. Results revealed that the introduction of erythritol and sucrose improved the hardness of the gels, fixed more free water, accelerated the rate of gel structuring, and enhanced the gel strength. FT-IR confirmed the reinforced hydrogen bonding and hydrophobic forces between the pectin chains after introducing co-solutes. And it could be observed clearly by SEM that the cross-linking density of gel network enhanced with co-solutes. Furthermore, gel disruption experiments suggested the presence of ionic interaction, hydrogen bonding, and hydrophobic forces in LMP gels. Finally, we concluded that the egg-box regions cross-linked only by LMP and Ca were too weak to form a stable gel network structure. Adding co-solutes could increase the amount of cross-linking between pectin chains and enlarge the cross-linking zones, which favored the formation of a dense gel network by more hydrogen bonding and hydrophobic forces. Sucrose gels had superior physicochemical properties and microstructure than erythritol gels due to sucrose's excellent hydration capacity and chemical structure characteristics.
蔗糖和糖醇等共溶质在低甲氧基果胶（LMP）凝胶化过程中起着重要作用。为了探究其凝胶化机制，我们研究了LMP在赤藓糖醇和蔗糖存在下与钙的凝胶化行为。结果表明，赤藓糖醇和蔗糖的引入提高了凝胶的硬度，固定了更多的自由水，加速了凝胶结构形成的速率，并增强了凝胶强度。傅里叶变换红外光谱（FT-IR）证实了引入共溶质后果胶链之间增强的氢键和疏水作用力。通过扫描电子显微镜（SEM）可以清楚地观察到，共溶质使凝胶网络的交联密度增加。此外，凝胶破坏实验表明LMP凝胶中存在离子相互作用、氢键和疏水作用力。最后，我们得出结论，仅由LMP和钙交联的“蛋盒”区域太弱，无法形成稳定的凝胶网络结构。添加共溶质可以增加果胶链之间的交联量并扩大交联区域，这有利于通过更多的氢键和疏水作用力形成致密的凝胶网络。由于蔗糖具有出色的水合能力和化学结构特征，蔗糖凝胶比赤藓糖醇凝胶具有更优异的物理化学性质和微观结构。
