Why Does Coffee Dry Your Mouth?

There’s a common belief that coffee causes dry mouth because caffeine dehydrates the body. However, this isn’t true when consumed in moderate amounts, as caffeine doesn’t significantly affect the body’s water-salt balance. In fact, coffee can be just as hydrating as water when consumed in moderation.

The Real Cause of Dry Mouth After Drinking Coffee

The dryness some people feel after drinking coffee isn’t due to dehydration, but rather to the astringent properties of the beverage. Other drinks and foods, such as wine, teas, or certain berries, can also cause a similar dry sensation.

What Causes Astringency in Coffee?

Coffee’s astringency comes from tannins, a group of polyphenols also found in tea. When we drink coffee, these tannins interact with our saliva, reducing its lubricating properties and causing it to form deposits on the tongue. This reaction leads to the feeling of dryness or astringency.

Caffeine itself can also reduce saliva production, contributing to the sensation of dry mouth.

In moderate amounts, astringency adds complexity to coffee’s flavor. However, many people prefer their coffee to be less astringent, and fortunately, there are ways to reduce this effect.

Factors That Affect Astringency in Coffee

If you want to make your coffee less astringent, you can adjust several factors:

• Milk or cream can help reduce the astringency by coating the tannins and softening their impact.
• The length of time you brew your coffee affects its astringency. For example, cold brew coffee tends to be more astringent than pour-over coffee. This is because longer extraction times result in more tannins being dissolved into the coffee. Tannins don’t easily dissolve in water, so most of them only affect the flavor when the coffee is highly extracted—typically after 30% extraction.
• Over-extracted coffee (when brewed too long) will have more tannins and be more astringent, while under-extracted coffee will have less.

Other factors that influence coffee astringency include:

• Higher acidity and saltiness in coffee can enhance the perception of astringency.
• The less sugar you add to your coffee, the stronger the astringency will taste.
• Finely ground coffee beans tend to produce a more astringent brew.
• Cold coffee is usually more astringent than hot coffee. Adding sugar can help balance the taste and reduce astringency.
• The amount of fat or oil in your coffee, such as those naturally present in the beans or added through milk or cream, can also influence the level of astringency.

Conclusion

Coffee doesn’t dry your mouth due to dehydration, but rather due to the astringent properties of tannins interacting with saliva. By adjusting factors like brew time, grind size, or adding milk, you can reduce the astringency and enjoy a smoother cup of coffee that suits your taste.