Abstract Processing, stability and sensorial perception of food foams are tightly related to their microstructure and flow behavior. Characterization of corresponding physical parameters is central for product development and quality control. An experimental setup enabling in-situ characterization of yield stress, gas volume fraction and bubble size distribution at different heights within a foam column created in a commercial whipping device is presented. Reliable determination of these quantities is shown. Foams made from regular and reconstituted milk have been investigated. Gas volume fraction and bubble size increase monotonically during free drainage. Related to the changes in these parameters, the yield stress increases strongly during initial drainage and weaker in mature foams. Gradients of the structural and rheological parameters along the direction of gravity increase over time. Yield stresses in these milk foams are significantly higher than predicted from phenomenological modelling including the above parameters and we attribute this to interfacial elasticity contributions.

中文翻译：

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商业发泡装置中牛奶泡沫的原位流变学和结构表征

摘要 食品泡沫的加工、稳定性和感官知觉与其微观结构和流动行为密切相关。相应物理参数的表征是产品开发和质量控制的核心。展示了一种实验装置，能够对商业搅打装置中创建的泡沫柱内不同高度的屈服应力、气体体积分数和气泡尺寸分布进行原位表征。显示了这些数量的可靠确定。已经研究了由普通牛奶和复原乳制成的泡沫。在自由排水过程中，气体体积分数和气泡尺寸单调增加。与这些参数的变化相关，屈服应力在初始排水过程中强烈增加，而在成熟泡沫中较弱。沿重力方向的结构和流变参数的梯度随时间增加。这些牛奶泡沫中的屈服应力明显高于包括上述参数在内的现象学模型的预测，我们将其归因于界面弹性贡献。