In this study, the relationships between structure and rheology (at small and large deformations) of amidated low-methoxyl (LMA) citrus and apple pectin gels were investigated considering how does these relationships can be modulated by soluble solids (sucrose), pectin types and characteristics. For that purpose, various LMA pectins with varying degrees of methyl esterification (DE) and amidation (DA), processed from citrus peels and apple pomace, were used. Scaling models of biopolymer gels have been critically discussed in respect to pectin critical gelling concentration (C0) and their structural variabilities. It was demonstrated that, whatever the types of LMA pectins and their structural variabilities, scalar percolation and quadratic models can be efficiently used for the prediction of the storage modulus G′ and C0 as other biopolymer gels. Fractal approach reveals that the origin of the LMA pectin gel elasticity is more in harmony with an enthalpic network of rod-like filaments with bending rigidity ruling the network's elasticity. The addition of sucrose induced an anticipation of the gelation temperature and an important improvement of the viscoelastic properties of the resulting gels. It was also shown that the most tough gels are obtained for citrus pectins due to the higher level of neutral sugar side chains in apple pectins that can hinder preponderant ca-bridging sites unlike citrus pectins. Finally, it was shown that unlike the firmness and hardness of the gels which appear to be more driven by the amide groups, the deformability of the gels is rather governed by the methyl ester groups.

中文翻译：

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了解酰胺化低甲氧基柑橘和苹果果胶凝胶的结构/流变学关系：蔗糖、果胶类型和特性的影响


在这项研究中，研究了酰胺化低甲氧基 （LMA） 柑橘和苹果果胶凝胶的结构与流变学（在小变形和大变形时）之间的关系，考虑了可溶性固体（蔗糖）、果胶类型和特性如何调节这些关系。为此，使用了由柑橘皮和苹果渣加工而成的各种具有不同程度甲酯化 （DE） 和酰胺化 （DA） 的 LMA 果胶。生物聚合物凝胶的缩放模型在果胶临界胶凝浓度 （C0） 及其结构变化方面得到了批判性的讨论。结果表明，无论 LMA 果胶的类型及其结构变化如何，标量渗流和二次模型都可以像其他生物聚合物凝胶一样有效地用于预测储能模量 G′ 和 C0。分形方法表明，LMA 果胶凝胶弹性的来源与棒状细丝的焓网络更协调，弯曲刚度支配网络的弹性。蔗糖的添加诱导了对凝胶温度的预期，并显着改善了所得凝胶的粘弹性。研究还表明，由于苹果果胶中高水平的中性糖侧链会阻碍与柑橘果胶不同，柑橘果胶可以获得最坚韧的凝胶。最后，结果表明，与凝胶的硬度和硬度不同，凝胶的硬度似乎更多地由酰胺基团驱动，而凝胶的变形性则受甲酯基团的控制。