Tribology and QCM-D approaches provide mechanistic insights into red wine mouthfeel, astringency sub-qualities and the role of saliva

Abstract

Wine mouthfeel and astringency play an important role in shaping the organoleptic quality and have been associated with tannin-salivary protein colloidal interactions. The mechanistic drivers of wine mouthfeel, especially those creating distinct astringency sub-qualities percepts, are yet to be fully realised due to the lack of appropriate measures. This study researched the friction behaviours of saliva-wine interactions, that allow inference of insights into the physicochemical origins of several important wine mouthfeel attributes. The red wine sample sets were created by doctoring various levels of ethanol, tannin, pH and mannoprotein on a Malbec. Samples were profiled sensorily and chemically. The friction behaviours of wine-saliva interaction and salivary viscoelasticity were investigated by soft-tribological protocols plus quartz crystal microbalance with dissipation. The sensory scores of mouthfeel attributes were modelled by physicochemical parameters using partial least squares regression. Results suggested that burning and resalivation are non-frictional-derived sensations driven by ethanol and acidity, respectively. Drying, grippy and rough are driven by tannin's adsorption on salivary film, which cause poor lubricity and a film strip-off thus exhibit as high boundary friction in tribology. Pucker is not directly driven by tannin but the weak viscoelasticity of salivary film, which is exhibited as the fast rate of friction increase in tribology. Smoothness is driven by less salivary protein precipitation, a highly viscoelastic salivary film, or the viscosity effects from mannoprotein. Fullness is driven by high viscosity by high ethanol. These models support the theory that wine mouthfeel attributes have dissimilar physicochemical origins that lead to distinct sensory experiences.