Researchers are discovering that plant-based milks have unique physical properties that set them apart from traditional dairy. A recent study found that most plant-derived milks flow and drip in ways that are far more complex than cow or goat milk, a difference rooted in the ingredients that keep them shelf-stable and creamy.
The Science of Flow: Shear Thinning
The research team, led by Vivek Sharma at the University of Illinois Chicago, examined eight different milk types: cow, goat, pea, soy, oat, almond, coconut, and rice. They measured viscosity—how easily a liquid flows—and found that all the plant-based milks except rice milk exhibit shear thinning.
Shear thinning means the milk becomes less viscous (flows more easily) under pressure. This behavior is typical of non-Newtonian liquids like ketchup or shampoo. In contrast, dairy milks maintain a consistent viscosity regardless of pressure.
The Role of Gums
The key difference lies in the tiny amounts (often less than 0.1%) of gums added to plant milks. These gums, derived from legumes or bacteria, improve shelf life and create a smoother mouthfeel. They’re also the reason why plant milks behave so differently from dairy.
Everyday Implications
The non-Newtonian nature of these plant milks affects how they behave in real-world scenarios. For example:
- A spill of plant milk will spread more easily across a surface.
- A cookie dunked in plant milk will get a thinner coating.
These seemingly minor details matter because they influence the user experience and potentially even flavor perception.
The Future of Drink Design
Sharma believes that understanding the physics of milk composition could lead to designing new beverages with precisely tailored properties. While experienced food scientists rely on intuition, rigorous physical models and measurements can accelerate innovation in the beverage industry. The findings were presented on March 18 at the American Physical Society Global Physics Summit in Denver, Colorado.
By combining scientific rigor with practical knowledge, researchers and manufacturers can create plant-based milks that not only mimic dairy but also offer unique and improved sensory experiences.
