There’s no doubt about it, we live in a sensual world. As consumers, we spread, we squeeze and we scoop; we manipulate in our mouths and we swallow; how a product feels can make or break it in the experience-driven marketplace.
From the “stiff peaks” of meringue to the creamy smoothness of a skin treatment, from the soothing lubrication of eye drops to the mouth-watering string of hot mozzarella on our pizza - rheology, arguably, plays the dominant role in sensory and texture appeal for many products. Stiffness, smoothness, fluidity, pliability and slipperiness are typical qualities of interest - just watch a cookery show or a cosmetics ad and you’ll see these and other attributes aplenty – and here’s the thing: they all have rheological analogues - properties that can be measured and correlated to those critical consumer qualities we look for.
Using rheological techniques we can simulate the actions of or hands, our mouths or any other body part for that matter, in contact with our product:
Stress ramps can “feel” the rigidity and ultimate breaking point of a delicate soft-solid.
Shear rate steps and ramps can mimic application of a material to the skin.
Oscillatory frequency sweeps and creep tests can probe the compliance and deformability of a material over long-lived and short-lived stress applications.
Normal stress measurements can identify the ability for a material to form a lubricating layer between surfaces in contact.
Slip and pull-off tests tell us about the adhesive qualities and interaction of products with various surfaces.