Rheological and microstructural investigation of oat β-glucan isolates varying in molecular weight
Rheological and microstructural investigation of oat β-glucan isolates varying in molecular weight
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DOI：
10.1016/j.ijbiomac.2011.05.014
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发表时间：
2011-10-01
影响因子：
8.2
通讯作者：
Tosh, Susan M.
中科院分区：
文献类型：
--
作者：
Agbenorhevi, Jacob K.;Kontogiorgos, Vassilis;Tosh, Susan M.
研究了不同相对分子质量燕麦β-葡聚糖水溶液的流变性和微观结构。用~(13)C核磁共振波谱和高效尺寸排阻色谱(HPSEC)对产物的结构和相对分子质量进行了表征。用原子力显微镜(AFM)研究了β-葡聚糖分散体的微观结构。以干重计，β-葡聚糖含量在78-86%之间，其相对分子质量、特性粘度和临界浓度分别为142-2800×10(3)g/mol、1.7-7.2dl/g和0.25-1.10g/dl。流动和粘弹性行为高度依赖于相对分子质量和β-葡聚糖分散体的浓度。在高浓度下表现出假塑性行为，在低浓度下表现出明显的牛顿行为。在相同浓度下，相对分子质量越高，粘度越高。COX-Merz规则适用于较高浓度下的低相对分子质量样品，而较高相对分子质量样品在大于1.0%w/v的浓度下偏离。力学谱随相对分子质量和浓度的变化是典型的缠绕生物聚合物溶液。AFM图像显示，通过分散在整个系统中的单个聚合物链连接形成的簇或聚集体。聚集体的尺寸随着所研究样品的相对分子质量的增加而增加，并与样品的流变学行为有关。皇冠版权所有(C)2011由爱思唯尔出版。保留所有权利。
The theological properties and microstructure of aqueous oat beta-glucan solutions varying in molecular weight were investigated. The structural features and molecular weights (MW) were characterized by C-13 NMR spectroscopy and high performance size-exclusion chromatography (HPSEC), respectively. The microstructure of the beta-glucans dispersions was also examined by atomic force microscopy (AFM). The samples with beta-glucan content between 78 and 86% on a dry weight basis had MW, intrinsic viscosity ([eta]) and critical concentration (c*) in the range of 142-2800 x 10(3) g/mol, 1.7-7.2 dl/g and 0.25-1.10 g/dl, respectively. The flow and viscoelastic behaviour was highly dependent on MW and on the concentration of the beta-glucans dispersions. Pseudoplastic behaviour was exhibited at high concentrations and Newtonian behaviour was evident at low concentrations. At the same concentration, the viscosity was higher for higher MW samples. The Cox-Merz rule was applicable for the lower molecular weight samples at higher concentrations whereas the high molecular weight sample deviated at concentrations greater than 1.0%, w/v. The mechanical spectra with variation of both MW and concentration were typical of entangled biopolymer solutions. AFM images revealed the formation of clusters or aggregates linked via individual polymer chains scattered heterogeneously throughout the system. The aggregate size increased with the molecular weight of the samples investigated and has been linked to the theological behaviour of the samples. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.