How do pH, titratable acidity and acid composition impact the temporal profile of wine mouthfeel?

Abstract

Acid composition is an important quality indicator of wine. The ratios and concentrations of various acids existing in wine result in differences in pH and titratable acidity (TA), as well as distinct sensory characteristics. Previous studies observed the correlation between wine sourness perception and TA but not pH. However, few studies had investigated whether the wine mouthfeel attributes are also influenced by acid composition. This study investigated whether pH and TA, contributed by distinct wine acid composition, play different roles in influencing wine mouthfeel attributes. The study evaluated changes of malic acid, tartaric acid in a model wine system and lactic acid into a hydroalcoholic matrix. Then two model wine sample sets were created by controlling pH at two constant levels while allowing varying TA; and controlling TA at two constant levels while allowing varying pH. Samples were sensorily evaluated by a progressive profiling method and instrumentally tested by a soft-tribology approach looking at friction change of salivary pellicle upon contacting the samples. Results suggested that during the oral process of evaluation, the maximum sensory strength of pucker was dependent on pH, and the sensory decaying rate of pucker was dependent on TA. By comparison, the sensory decaying rate of drying, chalkiness and roughness were significantly dependent on pH. At constant pH or TA, the salivary tribology responses of wines with different acid composition were also distinct. It appears that wine temporal mouthfeel profiles were impacted by both pH and TA, while wine acid composition also plays a role.