Shear and extensional rheology of animal and plant-based milks*

Climate change, lactose intolerance, growing population are among many reasons to seek plant-based alternatives to animal milks. The color, texture, mouthfeel, and rheology of animal milk depends largely on the size, density, and concentration of the fat droplets and proteins (and their aggregates) within the dispersed phase. In this study, we characterize commercial animal and plant-based milk formulations using shear and extensional rheometry. We highlight the challenges due to interfacial viscoelasticity, microstructural changes and thixotropy involved in characterizing and emulating the rheological properties of such low viscosity fluids. Comparison of commercial samples of plant-based milks to bovine and goat milk show distinct response in steady shear viscosity characterized by torsional rheometry and extensional response evaluated using dripping-onto-substrate (DoS) protocols.