Regular drinkers of green tea may be altering how they perceive flavors, a Cornell University food scientist reports in the January issue of the journal Food Quality and Preference. Karl Siebert blames polyphenol-rich drinks, such as green tea, with boosting astringent sensations and our sensitivity to acids. He stumbled on the finding while studying the relationship between polyphenols, the chemical compounds in plants, and protein chains in drinks such as beer and apple juice. He spent 18 years working in a brewery before becoming an academic, a news release from Cornell says.

Knowing that acids together with polyphenols taste more astringent than either alone, Siebert and colleagues asked a group of panelists to rate the intensity of astringency of several dilute solutions of acids. Most of the people reported a mild difference. Others had a more dramatic sensitivity. Siebert dug deeper to determine that the most sensitive were regular green tea drinkers.

He then measured the polyphenol levels in saliva of people on days before, during and after they consumed several cups of green tea. This showed that saliva normally contains polyphenols, and there are large differences among individuals. Regular green tea and red wine drinkers had the highest levels.

\”It appears that there is a metabolic pool of polyphenol that is influenced by dietary habits, and that the salivary polyphenol level influences perception of astringency caused by acids,\” Siebert says.