Interfacial rheology of interfaces stabilized by food ingredients has been studied extensively within the limits of small and slow deformations, within the linear viscoelastic regime (LVR). However, in practice, products such as foams or emulsions undergo fast and large deformations during food processes such as chewing. emulsifying, or foaming. In this study, we used capillary break-up and droplet formation to observe and quantify large and fast deformations of such interfaces, in the presence of surface viscoelasticity. We studied the inertial thinning of the liquid neck during drop formation using high-speed imaging. We tested solutions of several surface active molecules, including two low molecular weight surfactants (SDS and Tween 20), two milk proteins (β-Lactoglobulin, Bovine Serum Albumin) and the saponin Escin. Escin showed the most significant effect on the shape of the neck and neck thinning dynamics. Interfacial shear rheology measurements indicated that the unusual breakup observation of Escin solutions was related to the high viscoelastic surface shear moduli. These high moduli, and the resulting more symmetric and shorter neck shape observed for the proteins and Escin, are associated with the formation of solid-like interfacial structures. However, the presence of a viscoelastic interface did not affect the inertial thinning regime, which indicates that the solid structures were broken down locally at the area of minimum radius (Rmin), and affected only the shape outside this region. The results of this work therefore, show that interfacial measurements within the LVR are not entirely representative for fast and large deformations well beyond linearity.

中文翻译：

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界面粘弹性和老化对液滴形成和破裂的影响

由食品成分稳定的界面的界面流变学已在线性粘弹性状态 (LVR) 内小而缓慢的变形范围内进行了广泛的研究。然而，在实践中，泡沫或乳液等产品在咀嚼等食品加工过程中会发生快速而大的变形。乳化或起泡。在这项研究中，我们使用毛细管破裂和液滴形成来观察和量化这种界面在存在表面粘弹性的情况下的大而快速的变形。我们使用高速成像研究了液滴形成过程中液体颈部的惯性变薄。我们测试了几种表面活性分子的溶液，包括两种低分子量表面活性剂（SDS 和吐温 20）、两种牛奶蛋白（β-乳球蛋白、牛血清白蛋白）和皂苷七叶素。七叶树素对颈部形状和颈部变薄动力学的影响最为显着。界面剪切流变学测量表明，七叶素溶液的异常破裂观察与高粘弹性表面剪切模量有关。这些高模量以及由此观察到的蛋白质和七叶树素的更对称和更短的颈部形状与固体状界面结构的形成有关。然而，粘弹性界面的存在不影响惯性减薄机制，这表明固体结构在最小半径 (Rmin) 区域局部分解，仅影响该区域外的形状。因此，这项工作的结果，