Why Does Coffee Dry Your Mouth?

There is a common misconception that coffee causes dry mouth because caffeine dehydrates the body. However, this is not true in moderate amounts because caffeine does not affect the water-salt balance. In addition, coffee has the same hydrating properties as water when consumed in moderation.

The dryness in the mouth that some people experience after drinking coffee is actually caused by the astringent properties of the beverage rather than dehydration. It’s worth noting that dry mouth can also be caused by other beverages and products, such as wine, various teas, or berries.

Astringency of coffee

The astringency of coffee is caused by a group of polyphenols called tannins. Similar to tea, coffee is the main source of tannins in our diet. When we consume coffee, the tannins react with our saliva, causing it to lose its lubricating properties and form deposits on the tongue. It is worth noting that caffeine tends to reduce the production of saliva. This results in a feeling of dryness or astringency.

In moderate amounts, astringency adds a unique flavor to the drink. However, many people prefer coffee with less astringency. Fortunately, there are several ways to reduce the astringency of coffee.

What affects astringency?

If you want to make your coffee less astringent, there are a few things you can do. Adding milk to your coffee can help reduce astringency. In addition, how long you brew your coffee can also affect the level of astringency. For example, cold brew coffee tends to be more astringent than pour-over coffee.

Controlling the extraction time is key to limiting the amount of tannin in your coffee. A simple rule to keep in mind is that the longer the extraction time, the more astringent your coffee will be. This is because many tannins do not dissolve well in water and therefore only affect the taste of the coffee when the extraction is high. In fact, most of the tannins will not make it into your cup until the coffee has been extracted to about 30%. So over-extracted coffee will have more tannins, making it more astringent than under-extracted coffee.

In addition to extraction time, there are other factors that can affect the perception and taste of astringency in your coffee:

• The acidity and saltiness levels in your drink can make it feel more astringent. 
• The less sugar you add to your coffee, the stronger the astringency will be.
• The finer the coffee beans, the more astringent the resulting beverage.
• The temperature of your beverage can also affect its astringency. Cold coffee tends to be more astringent, so adding sugar can help balance the taste.
• The amount of fat and oil in your coffee can also affect the level of astringency.