How to Detect the Three Signs of Over-Extraction in Coffee by Taste? Where Does Astringency Come From and How to Solve Coffee Over-Extraction?

Overwhelming Bitterness

The first point is that coffee has overwhelming bitterness.

Bitterness is a misunderstood flavor realm.

The world's best coffees still carry a hint of bitterness, often expressed as dark chocolate, spices, or woody notes. These lower notes make the taste more rounded, balance sharper acidity, and are often pleasant in a full cup.

This is not the kind of bitterness we're talking about.

We're talking about harsh bitterness. It doesn't add depth or complexity to other flavors—it overshadows them.

This bitterness is caused by extracting a bunch of bitter chemical compounds from the grounds. Besides caffeine, these chemicals are usually extracted after everything else.

Coffee roasted very dark tends to contain more of these bitter chemical compounds from the start. So if you buy coffee beans from a super dark roasting company, your coffee will always be over-extracted.

Thin and Tasteless Sensation

The second point is the thin and tasteless sensation.

Over-extracted bitterness isn't just overwhelming. Sometimes it can completely kill other flavors, making your coffee taste lifeless, dull, and bland.

Have you ever taken a sip of coffee that you imagined would be great, only to find it particularly dull and bland? As long as your beans aren't stale and old, this might be the result of over-extraction.

Under-extracted coffee can also have a thin, dull taste, but this is another situation. In this case, strong acidity appears because other flavors that promote balance haven't been extracted from the grounds yet.

Dry Sandpaper Mouthfeel

The third point is the dry sandpaper mouthfeel when drinking.

Have you ever tasted coffee that makes your tongue feel dry and rough? Have you felt that the coffee completely sucks all the moisture from your mouth?

This is called astringency. This is the same thing that happens when drinking black tea or dry wine, but in coffee, it's a classic sign of over-extraction.

This sensation is usually caused by polyphenols, micronutrients common in all types of plants. These chemicals taste bitter and bind with saliva proteins, absorbing the tongue's natural lubricants and making it feel dry.

Sometimes it can be so strong that your tongue feels like sandpaper. Sometimes, when you swallow, you can almost feel something gently scraping the back of your tongue.

This isn't very pleasant, and it's a clear example of over-extraction.

FrontStreet Coffee's Solutions for Over-Extraction

For coffee over-extraction, FrontStreet Coffee here gives everyone three suggestions to solve it:

• Design the extraction time properly. Know that the length of extraction time is the main reason here. If you steep coffee too quickly, you can't extract enough sugars from the coffee beans. On the other hand, if the coffee steeps for too long, it will over-extract and cause the coffee to become bitter.
• Grind size occupies a very important position, and you need to try different grind sizes yourself to see what impact they have on the coffee, repeatedly refine, and find a balance point.
• Appropriately change the coffee-to-water ratio.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473