Abstract Partially denatured whey protein products (PDWPC's) can be classified based on the viscoelastic properties of their solutions. Strain sweeps show that PDWPC-A and –B and microparticulated WPC (MPWPC) with compact, spherical aggregated particles exhibit a strong strain overshoot. PDWPC-C and –D, on the other hand, which have open, elongated porous particles show a weak strain overshoot. The concentration dependence of the elastic modulus G′ in the linear viscoelastic region has a biphasic power law dependence with concentration for all protein products studied, except for WPC where G′ is independent of protein concentration. Frequency sweeps suggest that MPWC solutions form a strong physical gel at all concentrations above 14% (w/w). PDWPC-A and –B form weak gels over the same concentration range. PDWPC-C and –D also form weak gels at 14% protein (w/w) but strong physical gels at higher concentrations. The frequency dependence of G′ and G″ for all aggregated proteins show a power law dependence indicating fractal type structures. For all solutions above a critical concentration, the fractal dimensions span the range 1.6–2.3, indicating a range of gel network structures from open and diffuse to compact and dense. Adherence to the empirical Cox-Merz rule was observed in PDWPC-A, -C and –D at concentrations of 14 and 16% (w/w) protein, suggesting liquid-like behaviour. At higher protein concentrations the deviations from the Cox-Merz rule suggest more pronounced elasticity in the structure. For PDWPC-B, the behaviour is complex, with deviation from the Cox-Merz rule at low frequencies/shear rates, but correspondence at higher frequencies/shear rates at all concentrations. This indicates a frequency-dependent change from liquid-like behaviour over long timescale deformations, to a solid-like behaviour at short timescale deformations. MPWPC solutions of all concentrations do not follow the Cox-Merz rule, suggesting solid-like behaviour. The PDWPCs exhibit a complex rheological behaviour which suggests they could be versatile thickening, texturizing and fat replacement ingredients that will offer food manufacturers greater control over the texture of formulated fluid foods.

中文翻译：

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部分变性乳清蛋白产品的特性：粘弹性

摘要 部分变性乳清蛋白产品 (PDWPC) 可根据其溶液的粘弹性进行分类。应变扫描显示 PDWPC-A 和 -B 以及具有致密球形聚集颗粒的微粒 WPC (MPWPC) 表现出强烈的应变超调。另一方面，PDWPC-C 和 -D 具有开放的细长多孔颗粒，显示出微弱的应变超调。线性粘弹性区域中弹性模量 G' 的浓度依赖性对于所有研究的蛋白质产品具有双相幂律依赖性，但 WPC 除外，其中 G' 与蛋白质浓度无关。频率扫描表明 MPWC 溶液在所有浓度高于 14% (w/w) 时都会形成强物理凝胶。PDWPC-A 和 –B 在相同浓度范围内形成弱凝胶。PDWPC-C 和 –D 在 14% 蛋白质 (w/w) 时也形成弱凝胶，但在较高浓度时形成强物理凝胶。所有聚集蛋白质的 G' 和 G'' 的频率依赖性显示出幂律依赖性，表明分形类型结构。对于高于临界浓度的所有溶液，分形维数的范围为 1.6-2.3，表明凝胶网络结构从开放和扩散到紧密和密集的范围。在 14% 和 16% (w/w) 蛋白质浓度下，在 PDWPC-A、-C 和 -D 中观察到对经验 Cox-Merz 规则的遵守，表明其具有类似液体的行为。在较高的蛋白质浓度下，与 Cox-Merz 规则的偏差表明结构具有更明显的弹性。对于 PDWPC-B，行为很复杂，在低频率/剪切速率下偏离 Cox-Merz 规则，但在所有浓度下在更高频率/剪切率下的对应关系。这表明从长时间尺度变形的类液体行为到短时间尺度变形的类固体行为的频率相关变化。所有浓度的 MPWPC 溶液都不遵循 Cox-Merz 规则，表明具有类似固体的行为。PDWPC 表现出复杂的流变行为，这表明它们可以作为多功能增稠、增稠和脂肪替代成分，使食品制造商能够更好地控制配制流体食品的质地。暗示类似固体的行为。PDWPC 表现出复杂的流变行为，这表明它们可以作为多功能增稠、增稠和脂肪替代成分，使食品制造商能够更好地控制配制流体食品的质地。暗示类似固体的行为。PDWPC 表现出复杂的流变行为，这表明它们可以作为多功能增稠、增稠和脂肪替代成分，使食品制造商能够更好地控制配制流体食品的质地。