Zhang Xiaoqing, Hoobin Pam, Burgar Iko, Do My Dieu
CSIRO Manufacturing & Infrastructure Technology, Private Bag 33, Clayton South MDC, Clayton South, VIC 3169, Australia.
Biomacromolecules. 2006 Dec;7(12):3466-73. doi: 10.1021/bm0604698.
The mechanical properties, phase composition, and molecular motions of thermally processed wheat gluten- (WG-) based natural polymer materials were studied by mechanical testing, dynamic mechanical analysis (DMA), and solid-state NMR spectroscopy. The performance of the materials was mainly determined by the denaturization and cross-linking occurring in the thermal processing and the nature or amount of plasticizers used. The pH effect also played an important role in the materials when water was used as the only plasticizer (WG-w). Alkaline conditions modified the chemical structure of WG, possibly via deamidation; enhanced the thermal cross-linking of WG macromolecules to form a more stable aggregation structure; and promoted intermolecular interactions between water and all components in WG (proteins, starch, and lipid), resulting in a strong adhesion among different components and phases. The saponification of lipid under alkaline conditions also enhanced the hydrophilicity of lipid and the miscibility among lipid, water, and WG components. However, when glycerol was used with water as a plasticizer (WG-wg), the phase mobility and composition of the materials mainly depended on the content of glycerol when the water content was constant. During thermal processing under either acidic or alkaline conditions, glycerol was unlikely to thermally cross-link with WG as suggested previously. The advanced mechanical performance of the WG-wg materials was attributed to the nature of hydrogen-bonding interactions between glycerol and WG components in the materials. This caused the whole material to behave like a strengthened "cross-linked" structure at room temperature due to the low mobility of glycerol. The pH effect on phase mobility and compositions of WG-wg systems was not as significant as that for WG-w materials.
通过力学测试、动态力学分析（DMA）和固态核磁共振光谱法，研究了热加工小麦面筋（WG）基天然高分子材料的力学性能、相组成和分子运动。材料的性能主要取决于热加工过程中发生的变性和交联以及所用增塑剂的性质或用量。当水作为唯一的增塑剂（WG-w）时，pH值的影响在材料中也起着重要作用。碱性条件可能通过脱酰胺作用改变了WG的化学结构；增强了WG大分子的热交联，形成了更稳定的聚集结构；促进了水与WG中所有成分（蛋白质、淀粉和脂质）之间的分子间相互作用，导致不同成分和相之间具有很强的粘附力。碱性条件下脂质的皂化作用也增强了脂质的亲水性以及脂质、水和WG成分之间的混溶性。然而，当甘油与水一起用作增塑剂（WG-wg）时，在含水量恒定的情况下，材料的相迁移率和组成主要取决于甘油的含量。如前所述，在酸性或碱性条件下进行热加工时，甘油不太可能与WG发生热交联。WG-wg材料优异的力学性能归因于材料中甘油与WG成分之间氢键相互作用的性质。由于甘油的迁移率较低，这使得整个材料在室温下表现得像一个强化的“交联”结构。pH值对WG-wg体系相迁移率和组成影响不如对WG-w材料那么显著。
