Abstract A closed cavity rheometer was employed to assess the properties of concentrated protein materials before, during and after thermal treatment, using conditions that are relevant to the production of meat analogues. Pea and soy protein isolate and wheat gluten were used as model matrices. The analysis was done using Lissajous curves, both for small and large amplitude oscillatory shear deformation. The energy dissipation ratios based on the enclosed area inside the Lissajous curves characterize the plasticity of the materials. The results show that the modulus of wheat gluten increases during heating and remains elevated after cooling. In contrast, the moduli of pea and soy protein isolates decrease during heating. Subsequent cooling leads to properties that are similar to the rheological properties of unheated pea and soy protein isolates. Lissajous curves and energy dissipation ratios provide insight in the non-linear response. At 30 °C, pea and soy protein isolate have a higher dissipation ratio than wheat gluten. Upon a heat treatment and even after cooling, the dissipation ratio was smaller at similar strain amplitude compared with 30 °C. This indicates that heating induced more elasticity. Upon heating, pea protein isolate loses its elastic properties faster than soy protein isolate, while wheat gluten showed abrupt dissipation after extensive deformation. The observed characteristics are consistent with the behaviour during extrusion and shearing, in which wheat gluten forms extended filaments, while soy and pea protein isolates form a homogeneous matrix. Studying the large oscillatory shear behaviour during and after thermal treatment provides a more detailed picture of the rheological changes during processing, than one would obtain through classical rheology. The dissipation ratio summarizes the information in the Lissajous curves. These insights help to better identify material-structure-process relationships for concentrated plant protein materials during thermomechanical conversions, such as extrusion.

中文翻译：

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浓缩蛋白质的大小振荡剪切特性

摘要 使用闭腔流变仪评估浓缩蛋白质材料在热处理之前、之中和之后的特性，使用与肉类类似物生产相关的条件。豌豆和大豆分离蛋白以及小麦面筋用作模型基质。分析是使用 Lissajous 曲线完成的，包括小振幅和大振幅振荡剪切变形。基于 Lissajous 曲线内封闭区域的能量耗散率表征材料的塑性。结果表明，小麦面筋的模量在加热过程中增加，冷却后保持升高。相比之下，豌豆和大豆分离蛋白的模量在加热过程中会降低。随后的冷却导致与未加热豌豆和大豆分离蛋白的流变特性相似的特性。Lissajous 曲线和能量耗散比提供了非线性响应的洞察力。在 30 °C 时，豌豆和大豆分离蛋白的耗散率高于小麦面筋。在热处理后甚至冷却后，与 30°C 相比，在类似应变幅度下的耗散比更小。这表明加热会产生更大的弹性。加热后，豌豆分离蛋白比大豆分离蛋白失去弹性的速度更快，而小麦面筋在广泛变形后会突然消散。观察到的特征与挤压和剪切过程中的行为一致，其中小麦面筋形成延伸的细丝，而大豆和豌豆分离蛋白形成均匀的基质。研究热处理期间和之后的大振荡剪切行为提供了比通过经典流变学获得的更详细的加工过程流变学变化图。耗散比总结了 Lissajous 曲线中的信息。这些见解有助于在热机械转换（如挤压）过程中更好地识别浓缩植物蛋白材料的材料-结构-工艺关系。