title: Wine pH Prevails over Buffering Capacity of Human Saliva.
abstract: Wine is an acidic beverage; its pH (2.9-3.8) is critically important to its organoleptic properties. During degustation, wine interacts with <1 mL of mouth saliva, the pH of which is near 7.0. This is buffered predominantly by the carbonate/bicarbonate pair (pKa= 6.1). Few data are available on whether the buffering capacity of saliva may alter the pH of wine and thus its sensorial properties. In this study both in vitro and in vivo approaches were conducted to measure pH in mixtures of representative red and white wines with human saliva. Continuous additions of microvolumes of either wine to a definite volume (3 mL) of saliva in vitro resulted in a progressive and steep decline in the pH of the wine/saliva mixture. Thus, a few microliters of either wine (<0.27 mL) was sufficient to reduce the pH of saliva by 1 pH unit. Further additions of wine to saliva lowered the pH to that of the corresponding wine. In the in vivo assay, definite volumes (1.5-18 mL) of either wine were mixed for 15 s with the mouth saliva of individual healthy subjects before pH determination in the expectorated wine/saliva mixtures. Compared to saliva, pronounced decreases in pH were observed, thus approaching the pH of wine even with the smallest volume of wine in the assay. Altogether, these results demonstrate that the buffering capacity of wine prevails over that of saliva and that during degustation the pH of the wine/saliva mixture in the mouth is, at least temporarily, that of the corresponding wine.
authors.affiliation: Department of Agro-Industry and Enology, Faculty of Agronomical Sciences, University of Chile , P.O. Box 1004, Santiago, Chile.
authors.forename: Elías
authors.initials: E
authors.lastname: Obreque-Slier
authors.affiliation: Department of Agro-Industry and Enology, Faculty of Agronomical Sciences, University of Chile , P.O. Box 1004, Santiago, Chile.
authors.forename: Valeria
authors.initials: V
authors.lastname: Espínola-Espínola
authors.affiliation: Program of Cellular and Molecular Biology, Faculty of Medicine-ICBM, University of Chile , Independencia 1027, Santiago, Chile.
authors.forename: Remigio
authors.initials: R
authors.lastname: López-Solís
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D012463:Saliva / Q000737:chemistry*; D014920:Wine
keywords: buffering capacity; degustation; pH; saliva; titratable acidity; wine