The hidden rheology of wine: viscosity, astringency, and reduced oral states

Abstract

Wine is commonly described through aroma, taste, grape variety, terroir, ageing, and quality, but it is also a liquid experienced tactually in the mouth. This Perspective is a conceptual contribution rather than a report of new rheological experiments. Its purpose is to organize established knowledge on wine viscosity, oral tribology, astringency, and sensory texture into a compact rheological interpretation of wine mouthfeel. Typical dry table wines are low-viscosity liquids that behave nearly as Newtonian fluids, and their bulk viscosities are only slightly higher than that of water. Bulk viscosity is therefore a necessary baseline, but it cannot by itself explain descriptors such as body, smoothness, dryness, roughness, warmth, prickling, and astringency. These impressions arise from coupled physicochemical, tribological, trigeminal, and perceptual processes involving wine composition, temperature, ageing state, saliva, oral surfaces, friction, lubrication, tannin-salivary protein interactions, and sensory descriptor assignment. The central contribution of this article is to express these processes using a reduced oral-state framework. In this view, different wines can generate similar mouthfeel when they produce comparable oral rheological or tribological states, whereas wines with similar bulk viscosities can be perceived differently when their lubrication, frictional, or salivary interaction states diverge. This framework also explains why trained and untrained tasters may encounter partially common oral stimuli while assigning different sensory language. Wine mouthfeel is therefore not reducible to viscosity alone, but neither is it merely subjective; it is a mapped response from material properties to oral state, perception, language, and judgment.

Graphical abstract