Abstract This paper investigates the physical mechanisms of structure formation during high-moisture extrusion of vegetable proteins. Our model starts from the observation that extrudates with fibrous, meat-like structures exhibit water-rich and protein-rich domains. The origin and structure of these domains is attributed to a spinodal phase-separation process which occurs upon cooling of the extrudate. We investigate the process using continuum-mechanics simulations, considering the combined effects of viscous flow, thermal diffusivity, and the mixing thermodynamics of water and protein. This multi-physics problem is numerically solved using an unconventional mesh-free approach, the material point method (MPM), combined with the Cahn- Hilliard model of phase separation. The method incorporates both Eulerian and Lagrangian aspects, and is well suited to model multicomponent flows of history-dependent materials. Our simulations show that fiber-like structures are obtained when the ratio of phase separation rate, heat conduction rate, and flow rate are matched within a narrow window. Our results predict that the shape of the temperature profile within the cooling channel determines the structure of the phase-separated state. These findings suggest that the physical mechanism which causes fibrous structure formation is given by spinodal phase separation under the influence of a temperature gradient.

中文翻译：

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了解肉类替代品高水分挤压过程中纤维质地形成的机制

摘要 本文研究了植物蛋白高水分挤压过程中结构形成的物理机制。我们的模型从观察到具有纤维状肉状结构的挤出物表现出富含水和富含蛋白质的结构域开始。这些域的起源和结构归因于在挤出物冷却时发生的旋节线相分离过程。我们使用连续介质力学模拟来研究该过程，同时考虑粘性流动、热扩散率以及水和蛋白质的混合热力学的综合影响。这个多物理场问题使用非常规的无网格方法，即材料点法 (MPM)，结合 Cahn-Hilliard 相分离模型进行数值求解。该方法结合了欧拉和拉格朗日方面，并且非常适合模拟历史相关材料的多组分流动。我们的模拟表明，当相分离率、热传导率和流速的比率在窄窗口内匹配时，可以获得纤维状结构。我们的结果预测，冷却通道内温度分布的形状决定了相分离状态的结构。这些发现表明，导致纤维结构形成的物理机制是由温度梯度影响下的旋节线相分离给出的。我们的结果预测，冷却通道内温度分布的形状决定了相分离状态的结构。这些发现表明，导致纤维结构形成的物理机制是由温度梯度影响下的旋节线相分离给出的。我们的结果预测，冷却通道内温度分布的形状决定了相分离状态的结构。这些发现表明，导致纤维结构形成的物理机制是由温度梯度影响下的旋节线相分离给出的。