As many of you probably know from experience, sometimes when you drink a red wine you notice that your mouth gets very dry. This is usually attributed to the tannin levels in the wine—the “bigger” the tannins, the more it seems moisture is wicked away from your mouth and you’re left with something akin to the Sahara happening on your tongue.
So, what is really going on here? Is it the tannins? Why do they make your mouth feel so dry after sipping?
A study published in January in the Open Journal of Stomatology aimed to address a very similar question. In essence, what is the effect of tannic acid in different beverages on glandular function in the mouths of mice?
First, the salivary glands in the mouth are basically made up of two different types of parts: those that produce a sort of “preliminary saliva”, and those that absorb salt, and add potassium and bicarbonate to create the final hypotonic saliva. Having this hypotonic property allows the flavors of the food to better pass through the saliva into the taste buds so we can actually taste what it is we are eating or drinking.
It is during the transport of fluids as well as salt, potassium, and bicarbonate that problems with salivary secretions can arise. If something is preventing these processes from occurring, one could be left with excess saliva or alternatively dry mouth.
It is thought that tannic acid (TA) might mucks with this process thus often leaving the feeling of dry mouth after drinking some red wines. Specifically, TA might inhibit the calcium-activated transport channels that allow for diffusion of the necessary compounds needed to create the final saliva, resulting in decreased saliva production and observed dry mouth.