Regular consumption of the polyphenol-rich drinks, such as green tea and red wine, can boost astringent sensations and our sensitivity to acids, report Karl Siebert and colleagues, Cornell University, USA.

Regular red wine and green tea drinkers had the highest levels of polyphenols expressed in their saliva. Green tea was shown to directly elevate polyphenol levels. Polyphenol levels returned to an individual’s baseline level within half an hour of consuming the tea, but the underlying baseline level gradually rose with prolonged consumption of tea.

Panelists were given acidic solutions before, during and after a period of tea drinking and rated them for astringency and sourness. Astringency and sourness intensity ratings increased significantly during the period of tea drinking, showing that salivary polyphenol level influences perception of astringency.

• The effects of green tea drinking on salivary polyphenol concentration and perception of acid astringency
  K. J. Siebert, A. A. Maekawa, P.Y. Lynna,
  Food Quality and Preference, 2011, 22(1), 157-164.
  DOI: 10.1016/j.foodqual.2010.09.004