What Causes Coffee's Aftertaste? Where Are Taste Buds Distributed on the Tongue? Why Does Water Taste Sweeter After Drinking Coffee?

"It's~not~an~exaggeration~try it yourself: after drinking coffee, drink some water - the water will really taste very sweet!"

That was a comment from a customer at FrontStreet Coffee yesterday, and we found it interesting enough to unpack today. Sometimes, before tasting certain intense coffees (espresso, strong single origin), we take a sip of ice water first - rinsing the palate helps us read the flavors of such a concentrated cup. Drinking water after finishing the coffee plays the same role, and as the customer described, plain water suddenly emerges with a striking "sweetness."

Even if it is the very same water you used for that first "rinse," it tastes sweeter after the coffee than before. So why does this happen?

Why does water taste sweeter after drinking coffee?

That leads us to one of our five senses: taste. Sour, sweet, bitter, salty, and umami are the five flavors our taste buds can detect, and the organ doing the detecting is the taste buds on our tongue - tiny sensory structures made of taste cells, also called taste receptors. When the flavors of food and drink touch the taste buds, the cells are stimulated and send electrical signals to the brain, and only then do we perceive the taste.

Water tasting sweeter after coffee comes down to two mechanisms: the "taste contrast effect" and our "oral physiological functions." The taste contrast effect is the way one flavor shapes our perception of the next. When you experience one taste and then another, the first affects how the second registers - amplifying it, dampening it, even changing it. For example, eat something very sweet and then something bland: although the bland food contains no bitterness, the preceding sweetness suppresses the activity of bitter receptors and lowers their sensitivity, which makes the bland food taste faintly bitter.

"Oral physiological functions" refers to the way our salivary glands ramp up saliva production when stimulated. Saliva contains enzymes such as amylase, which bind to or break down certain components in food and drink, generating sweetness in the process. In short, water tasting sweeter after coffee is the combined work of these two factors - and the same principle underlies aftertaste!

When we drink coffee, it stimulates the mouth into secreting more saliva, and the enzymes in that saliva break down certain coffee components into sweet substances - hence the sweetness that follows. Meanwhile, coffee's bitter compounds form a sharp contrast against that sweetness, so when it arrives, the sweetness stands out all the more.

Under the combined effect of these two factors, our sensitivity to sweetness rises after drinking coffee, and the surge of saliva sweetens what it touches. Take a sip of water at that moment, and the water will indeed taste remarkably sweet.

FrontStreet Coffee Recommendation

Want to try this experiment with a proper espresso? FrontStreet Coffee suggests these beans:

• FrontStreet Classic Blend - built for espresso and moka pots, with an outstanding, dense crema that even a beginner on a home machine can pull. The traditional Mandheling-Brazil recipe gives a mellow, rounded cup that suits lattes, cappuccinos, and Dirty alike - the reliable first choice for home and shop alike.
• FrontStreet Signature Blend - our shop's longest-running espresso, nearly ten years on the front line of Americanos and lattes. Cerrado Brazil meets Huila Colombia for nut, chocolate, and caramel aromas with a comfortable acidity - the most familiar "classic espresso" flavor there is.
• FrontStreet Natural Huakui SOE - an Ethiopian single origin from Guji's Hambella highlands (up to 2300 meters), natural-processed and medium roasted. As an Americano or latte it brings creamy strawberry, cocoa, berries, a light floral note, and black tea - a SOE that shows just how sweet "contrast" can get.