Red Wine’s Drying Sensation Linked to Tannins Blocking Water Channels in Mouth, Study Finds

A recent study has provided new insight into why red wine often leaves a drying, puckering sensation in the mouth. The research, published in the Journal of Agricultural and Food Chemistry, focused on the role of tannins—compounds found in red wine that have long been associated with astringency, the sensation described as drying or lip-puckering.

The study was conducted by a team of scientists in Australia who used both laboratory experiments and trained tasting panels to investigate how tannins interact with the human mouth. The researchers found that tannins act on aquaporin water channels located in the tongue and salivary glands. These channels are responsible for regulating water movement in and out of cells. According to the findings, tannins appear to block these channels, allowing more water to leave the cells than enter, which leads to the characteristic drying sensation.

To reach these conclusions, the team first confirmed that aquaporin channels—specifically AQP1, AQP2, and AQP5—are present in human tongue and salivary gland tissues. They used immunohistochemistry techniques on human tissue samples to identify where these channels are expressed. The results showed strong expression of AQP1 and AQP2 in tongue epithelial cells and high levels of AQP5 in salivary glands.

The researchers then used a combination of laboratory assays and sensory evaluations. In one set of experiments, they exposed frog oocytes engineered to express human aquaporin channels to red wine samples with varying tannin concentrations. They measured how quickly water could move through these channels under different conditions. The results showed that higher tannin concentrations led to greater inhibition of water movement through the channels.

At the same time, trained tasting panelists evaluated a range of red wines for astringency using established sensory analysis methods. Wines with higher tannin content were consistently rated as more astringent by the panelists. The researchers also measured how the addition of tannins affected the friction between saliva and wine using tribology—a technique that quantifies lubrication between surfaces. Higher tannin levels increased friction, which is consistent with a drier mouthfeel.

The study also tested isolated compounds such as tannic acid and aluminum sulfate (alum), both known for their astringent properties. These compounds produced similar effects on aquaporin channel activity and were rated as more astringent by human panelists as their concentrations increased.

One important finding was that dealcoholized red wine had similar effects on aquaporin channels as regular red wine, indicating that it is the non-alcoholic components—primarily tannins—that are responsible for blocking water movement and causing astringency.

The researchers propose that this mechanism—tannins acting as a “lid” on aquaporin channels—helps explain why red wine can feel so drying in the mouth. When these channels are blocked, water leaves oral cells more easily than it enters, leading to cell shrinkage and a sensation of dryness or puckering. This process may also reduce saliva production by affecting aquaporins in salivary glands, further intensifying the dry feeling.

The study’s authors say their findings help clarify longstanding debates about how astringency is perceived. While previous theories have focused on protein aggregation in saliva reducing lubrication, this research suggests that direct effects on water transport at the cellular level also play an important role.

This work adds to our understanding of how people experience beverages like red wine and could inform future research into food and drink design. It also opens up new questions about how other foods or drinks with high tannin content might affect mouthfeel through similar mechanisms.

The research was carried out with ethical approval for both human sensory testing and animal experiments. The study involved small sample sizes for some tests, such as saliva collection for tribology measurements, but provides pilot data for further investigation.

Overall, this study offers a molecular explanation for why red wine can make your mouth feel dry or puckered—a sensation familiar to many wine drinkers—and highlights the complex ways in which food and drink interact with our senses at both chemical and cellular levels.