Microstructure and rheological behaviour of particulate β-lactoglobulin gels
Microstructure and rheological behaviour of particulate β-lactoglobulin gels
复制标题
颗粒β-乳球蛋白凝胶的微观结构和流变行为
DOI：
10.1016/s0268-005x(09)80172-0
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发表时间：
1993
影响因子：
10.7
通讯作者：
A. Hermansson
中科院分区：
文献类型：
--
作者：
M. Stading;M. Langton;A. Hermansson
网络的微观结构以及在 pH 5.3 下形成的颗粒 β-乳球蛋白凝胶链已通过显微镜进行了表征。测量了小变形和大变形时微观结构对流变性能的影响。结果表明，微观结构取决于所使用的加热速率。以快速加热速率 (5–10°C/min) 形成的凝胶由孔径为 20–30 μm 的均匀网络组成。这些线由大小均匀的球形颗粒连接而成，就像一串灵活的珠子一样。在缓慢的加热速率（0.1–1°C/分钟）下，网络具有较大的孔隙，约 100–150 μm。以 0.1°C/min 形成的网络是不均匀的，具有小孔和大孔区域。在缓慢的加热速率下，粒度分布更宽，并且由多个颗粒熔合在一起形成的线更粗。断裂性能的拉伸测量表明，由于网络结构，在快速加热速率下形成的凝胶在断裂时具有更高的应力和应变。网络最弱元素的尺寸是根据缺口敏感性测量推导出来的，并且与孔径密切相关，即断裂从最大的孔隙开始。粘弹性测量表明，缓慢加热速率下形成的凝胶具有较高的储能模量 G'，这可以通过线束的微观结构来解释。熔合在一起的粗颗粒线更硬，因此比在快速加热速率下形成的柔性线具有更高的储能模量。测量了 G' 的浓度依赖性，并将假设簇聚类的模型应用于结果。该模型表明，颗粒凝胶在测量的浓度范围内是自相似的，分形维数约为 2.5。
The microstructure of the network as well as the strands of particulate β-lactoglobulin gels formed at pH 5.3 have been characterized by microscopy. The microstructural influence on the rheological properties both at small and large deformations has been measured. It was shown that the microstructure depends on the heating rate used. Gels formed at a fast heating rate (5–10°C/min) consisted of a homogeneous network with pore sizes of 20–30 μm. The strands were formed by evenly sized spherical particles linked like a flexible string of beads. At a slow heating rate (0.1–1°C/ min) the network had larger pores, ~100–150 μm. The network formed at 0.1°C/min was inhomogeneous, with regions of small and large pores. The particle size distribution was broader at a slow heating rate and the strands, formed by several particles fused together, were thicker. Tensile measurements of fracture properties showed that the gels formed at a fast heating rate had higher stress and strain at fracture due to the network structure. The size of the weakest element of the network was deduced from notch sensitivity measurements and correlated well with the pore size, i.e. the fracture starts at the largest pores. Viscoelastic measurements showed that the gels formed at a slow heating rate had a higher storage modulus, G′, which was explained by the microstructure of the strands. The thick strands of particles fused together were stiffer, thus causing a higher storage modulus than the flexible strands formed at a fast heating rate. The concentration dependence of G′ was measured, and a model assuming clustering of clusters was applied to the results. The model shows that the particulate gels are self-similar within the region of concentration measured, with a fractal dimension of ~2.5.