Dynamic viscoelastic and tensile properties of gluten and glutenin gels of common wheats of different strength.
Dynamic viscoelastic and tensile properties of gluten and glutenin gels of common wheats of different strength.
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DOI：
10.1021/jf020719l
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发表时间：
2003-03
影响因子：
6.1
通讯作者：
Chia-Chien Lee;S. Mulvaney
中科院分区：
文献类型：
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作者：
Chia-Chien Lee;S. Mulvaney
以不同强度的加拿大普通小麦为原料，研究了谷蛋白和谷蛋白凝胶在25℃下的动态粘弹性特性。弛豫谱在特征弛豫时间（tau）处显示出最大强度。与此最大值相关的松弛模量作为谷蛋白或谷蛋白凝胶瞬态网络的强度（G(tau)）。同一品种的谷蛋白和谷蛋白凝胶的G（tau）比值从特强型品种的5.6到软质小麦的51.1不等。这提供了间接证据，表明麦胶蛋白组分在较弱的品种中更能削弱谷蛋白凝胶网络。此外，谷蛋白和谷蛋白凝胶均表现出广泛的应力松弛，加上加入l-半胱氨酸使谷蛋白凝胶在25℃时消除了网络结构，并产生幂律应力松弛谱，这表明谷蛋白中的瞬时网络是一个可逆的网络。这种幂律松弛模式在纠缠的聚合物熔体（聚二甲基硅氧烷）中没有看到。我们还发现，在单轴拉伸试验中，谷蛋白凝胶的黏度（G(tau) x tau）随拉伸应力的增加趋势最好。总之，这些结果表明，在表征水合谷物蛋白的线性粘弹性特性时，应同时考虑网络强度和松弛时间。
Dynamic viscoelastic properties at 25 degrees C of gluten and glutenin gels were obtained from Canadian common wheats of different strengths. The relaxation spectra showed a maximum intensity at a characteristic relaxation time (tau). The relaxation modulus associated with this maximum was taken as the strength of the glutenin or gluten gel transient network (G(tau)). The ratio of G(tau) for glutenin and gluten gels from the same cultivar ranged from 5.6 for an extra strong cultivar to 51.1 for a soft wheat. This gives indirect evidence that the gliadin fraction weakens the glutenin gel network more in weaker cultivars. In addition, the fact that both glutenin and gluten gels showed extensive stress relaxation coupled with the fact that addition of l-cysteine to a gluten gel eliminated the network structure at 25 degrees C and resulted in a power law stress relaxation spectrum suggests that the transient network in gluten is a reversible network. This power law relaxation pattern was not seen here for an entangled polymer melt (poly(dimethylsiloxane)). It was also found here that the viscosity of the gluten gel (G(tau) x tau) trended best with the tensile stress build-up in a uniaxial tensile test of gluten gels. Together, these results indicate that both network strength and relaxation times should be considered in characterizing the linear viscoelastic properties of hydrated cereal proteins.