Signs That Your Coffee Is Over-Extracted: What To Do

Signs That Your Coffee Is Over-Extracted: What To Do

Coffee extraction process

Coffee extraction is essential and is the least understood part of coffee making. The extraction process will determine the flavors, the acidity of the coffee, and the aromas as well. Most coffee drinkers don't understand the extraction process, so the coffee may not come out right. 

We know you want to have all the rich flavors and aromas from your coffee, so you have to continue reading to uncover all these. You’ll learn what extraction is, why some changes in the brewing process affect the flavor. Finally, how you can harness the process extraction to greatly improve your morning brew. We’ll walk you through all of it. By the time you are done reading this post, you’d have the power to improve the flavor of your coffee

Overview Of Extraction

Coffee brewing involves grinding coffee grounds and mixing them with hot water to bring out acid, flavors, and aromatic compounds from the coffee grounds. When we say coffee science, it is not science that cannot be comprehended, it is just hot water, sucking different flavors from the coffee beans.

When the grounds dissolve, it will transform the water poured into it into a coffee drink. Some things extract faster than the others, like the sugar in the coffee while the other things like the aromatic oils may take more time. The bitter flavors take longer to show.

Having balanced extraction means getting a morning brew with rich flavors, crisp but with more balanced acidity and little bitterness. Over extraction on the other hand happens when the coffee brewing goes beyond the usual sweet spot, resulting in a bitter coffee.

Note that over-extraction doesn't happen so fast, it happens slowly, so a cup of coffee today may be slightly over-extracted from another cup you brew tomorrow.  Over extraction of coffee can be avoided. We'd tell you what causes over-extraction of coffee, and 3 signs that your coffee is over-extracted.

What is over-extraction?

Over-extraction of coffee beans is a process of extracting beans too much, or too rapidly, in a coffee mill. It reduces the quality of the coffee. Over extraction destroys the delicate taste of coffee beans. It can cause your coffee to turn bitter and bitter after you drink it. It is time for you to stop over-extraction of coffee! But first, get to know the signs


As we previously mentioned, the coffee will get bitter and bitter the more you drink it. Note that bitterness in coffee is mostly misunderstood. Even the best coffee beans when brewed still have a hint of bitterness in them, but they will mostly be under flavors like woody, spicy and dark chocolate. These somewhat bitter tastes will balance the acids in the coffee. But all we just described is not the type of bitterness we are referring to. 

We are talking about coffee that is so bitter, the bitterness overshadows all the sweet flavors like chocolate and fruity. The bitter taste comes out after different chemicals from the grounds have been extracted, and it happens after every other thing has been extracted.

Coffees that are over roasted tend to have more of these bitter tastes. So we advise that you buy beans from reputable roasters. You don't want coffee that is over-extracted and so bitter. Gross


The bitterness will not just overpower some flavors, it can completely kill them. In other words, over-extracted coffee may taste so dull and bland. Have you ever experienced something like this? You finished brewing coffee, sat on your cushion, took one sip only to find out that the coffee is dull, bland, and unexciting? You may think it's the beans, that they are stale and old but most times, it is as a result of over-extraction.

Under extracted coffee may have a sour and dull taste, and it is different. The coffee's intense soured taste is a result of the fact that other flavors have not yet been extracted from the coffee. But in the case of over-extraction, the bitter and sour taste will overshadow the main flavors that were extracted in the first place.


Have you ever brewed coffee, and it tasted so dry and a bit scratchy on your tongue? Did the coffee suck out all the moisture in your mouth? What happened to you is called astringency. It is almost the same mouthfeel you get when you drink some kind of wine or black tea. But it is not a good taste in coffee it is a sign of over-extraction.

Let's get a bit into biology here, this astringent taste is caused by some micronutrients that are very common in plants. The chemicals have a bitter taste so when they meet with your saliva proteins, they will suck up the natural lubricants in your tongue, hence the dry sensation. 

The taste can be so intense sometimes that your tongue may feel like it is sandpaper. It is just coffee you wanted, not this unpleasant taste. We’d tell you the common mistakes that lead to brewing over-extracted coffee.

Causes of Over-Extraction

Using The Wrong Coffee Grinder

Often it's caused by a poorly designed grinder, too much power from your grinder, or maybe your grinder wasn't built to the specifications required by the coffee bean processing industry. But occasionally, over-extraction can be caused by how you're brewing the coffee.

This is how the coffee grinder can cause over-extraction: When you use a too-small coffee grinder. Coffee grinders designed for espresso/coffee-brewing are designed to accommodate beans about ½" in diameter and larger, or up to ¾", depending on the grinder you're using.

However, more often than not, they will grind coffee beans just barely small enough to produce a watery coffee that lacks that "Roastiness' and dries out the coffee. So when you use it like that to brew, the coffee will over-extract because the grinds are uneven.

Brewing for a longer time

Brewing longer than the required time will make over-extracted coffee. The grounds will originally release all the delicious flavors, but if you continue brewing after then, the grounds will begin to release bitter chemicals. For example, if you make coffee with a French press for more than 6 or 7 minutes, you may have over-extracted coffee because the ideal time for brewing with a French Press is 4 or 5 minutes. 

You disturb the brewing process if the brewing recipe involves you stirring the coffee grounds in water. You may overdo, and the coffee may over-extract. Shaking and swirling vigorously is a rough brewing method, and it can lead to accidental over-extraction.

You grind the grounds too fine

We previously mentioned that the type of coffee grinder used has a role to play in over-extraction, but the type of grounds used is part of it. Using finer grounds means the water will extract the compounds faster. The grind size pairs with the brewing method. That means, the finer the grinds, the less time you’d need for brewing.

Related: How To Grind Coffee

You don't remove the filter after brewing

Leaving the filter over the cup after using any pour-over method will over-extract the coffee. The bitter flavors will begin to enter the cup. When the pour-over dripper is drained, quickly remove the filter.

How To Prevent Over Extraction

  • Make sure you have a good grind: Most grinders are good for a cup of coffee. A bad grind will give you a burnt taste in the coffee, and reduce the coffee's strength.  Look for a good grinder that grinds lightly like the burr grinder.
  • Lubricate the grinder head: Coffee presses the grounds at the bottom of the mill, which is where it is easiest to press. Make sure you grease the grinder head, for a smooth grinding experience.
  • Watch the water temperature. Coffee beans are very sensitive to high temperatures, so you may need to adjust the water temperature. Using water that is too hot will burn the coffee and leave it with a bitter taste. 


This post is not about avoiding coffee at all. It is about avoiding over-extracted coffee. You have to try to escape the bitterness and dry mouthfeel. Now that you know the signs of over-extracted coffee and how to avoid it, you can fix the problem when brewing tomorrow. 

However, bear in mind that all this information will not work if you are brewing with over-roasted coffee beans (bitter beans). If you want to brew better coffee, you have to brew with specialty-grade freshly roasted beans. 

At Coffee Hero, we roast our beans every day and ship them a few hours after they have been roasted, so you won't have to bother about brewing with over-roasted beans. If you love to explore coffees with different flavors like floral, strawberry, and chocolatey, check out our site.

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