A micro- and macro-scale approach to probe the dynamics of sol-gel transition in cereal β-glucan solutions varying in molecular characteristics
A micro- and macro-scale approach to probe the dynamics of sol-gel transition in cereal β-glucan solutions varying in molecular characteristics
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DOI：
10.1016/j.foodhyd.2014.01.025
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发表时间：
2014-12-15
影响因子：
10.7
通讯作者：
Biliaderis, Costas G.
中科院分区：
文献类型：
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作者：
Moschakis, Thomas;Lazaridou, Athina;Biliaderis, Costas G.
众所周知，谷物β-葡聚糖具有对健康有益的功能特性，例如降低人类和动物的血浆胆固醇和餐后血糖水平；最近，这种效应被归因于这些水溶性纤维的粘度和凝胶化潜力。研究了分子大小和三聚体与四聚体 (DP3/DP4) 链段摩尔比不同的 β-葡聚糖溶液在老化时发生凝胶化的局部动力学。共焦显微镜、颗粒跟踪微观流变学和传统的整体剪切流变学测量已被用来研究不同长度尺度上多糖网络的微观结构和机械性能。 β-葡聚糖的结构特征，例如分子量和 DP3/DP4 比例，被发现是其胶凝特性和微观结构的重要决定因素。对于在 25°C 固化的 β-葡聚糖凝胶，微观流变学和本体流变学都表明，随着分子量的降低和 DP3/DP4 摩尔比的增加，胶凝时间减少，而胶凝速率随着储能模量增加。在所有研究的样品中，生成的β-葡聚糖组装体的颗粒簇的尺寸类似于1-15μm，并且簇最终相互连接以在可用空间上扩展以形成弹性网络。发现孔径和结构实体的尺寸在较低的 DP3/DP4 摩尔比值和高分子量的制剂中增加。结构实体的尺寸和致密性似乎在网络加固中发挥着重要作用。发现嵌入的示踪颗粒在 DP3/DP4 处经历与 2.1 类似的相对均匀的微环境，反映出链聚集体结构的速率相当慢。微观水平上的多糖网络动力学行为似乎并不总是与总体宏观响应相匹配。 (C) 2014 Elsevier Ltd. 保留所有权利。
Cereal beta-glucans are known to display functional properties with health benefits, such as reduction of plasma cholesterol and of postprandial serum glucose levels in humans and animals; such effects have been lately attributed to viscosity and gelation potential of these water soluble fibres. The local dynamics of beta-glucan solutions differing in molecular size and the molar ratio of trimers to tetramers (DP3/DP4) chain segments, which undergo gelation upon ageing, was investigated. Confocal microscopy, particle tracking microrheology and conventional bulk shear rheological measurements have been employed to study the microstructure and mechanical properties of the polysaccharide networks on various length scales. The structural features of beta-glucans, such as molecular weight and ratio of DP3/DP4, were found to be important determinants of their gelling properties and microstructure. For the beta-glucan gels cured at 25 degrees C both the microrheology and the bulk rheology revealed that with decreasing molecular weight and increasing DP3/DP4 molar ratio the gelation time decreased, while the gelation rate increased along with the storage modulus. In all samples studied, particulate clusters of beta-glucan assemblies were generated with size similar to 1-15 mu m and the clusters were eventually interconnected to expand over the available space to form an elastic network. The pore size and the structural entities were found to increase in size at lower values of the DP3/DP4 molar ratio and with preparations of high molecular weight. The size and the compactness of the structural entities seem to play an important role in the network reinforcement. The embedded tracer particles were found to experience relatively homogeneous microenvironments at DP3/DP4 similar to 2.1, reflecting a rather slow rate of chain aggregates structuring. The behaviour of the polysaccharide network dynamics at a microscopic level does not always seem to match the overall bulk macroscopic response. (C) 2014 Elsevier Ltd. All rights reserved.