How to Know if Your Coffee is Under or Over-Extracted?

You try your best daily to brew that perfect cup of coffee, striving for just the right amount of sweetness, acidity, boldness, and flavor. Simply put, you want a balanced cup of coffee. Well, understanding more about coffee extraction will help you achieve your goal.

First, we need to answer the question, “How do I know if my coffee is under or over-extracted?”

Your coffee is under-extracted if it tastes sour, salty, or soapy. Your coffee is over-extracted if it tastes burnt, bitter, or metallic. These unpleasant flavors can be solved by changing just a few things.

We all strive for a smooth-tasting cup of coffee and are dissatisfied when we taste anything but. Let’s dig a little deeper into each of the undesired tastes stated above and how to fix the extraction problem with each.

What is Coffee Extraction?

Before we get into how to know if your making coffee that is over or under-extraction, let’s be sure we all have a good understanding of what extraction is.

Extraction is the process of pulling the flavor out of the coffee bean through hot water. When hot water is combined with coffee grounds, a chemical reaction dissolves the flavor compounds. It’s essential to learn exactly how long your coffee grounds need to be extracted to avoid unwanted flavors.

During the brewing process, acids are the first to be extracted or taken from the coffee grounds. This explains why the first bit of coffee brewed will taste sour or salty. As the brewing comes to its completeness, the coveted oils, sugars, and other flavors will have had enough brewing time to be extracted from the coffee grounds. These final flavors balance out the initial flavors from the acids.

Under-Extraction

Under-extraction is when the coffee grounds are not given enough time to brew completely. As a result, not all of the beans’ oils, sugars, and wonderful flavors get a chance to be extracted and are still left in the grounds.

Different compounds in each bean are extracted at various times throughout the brewing process. Some are released early, and others need the entire length of the brew to be extracted. Sadly, if all these compounds cannot be extracted, you are left with an unbalanced cup of coffee.

To remedy under-extraction, ensure that the hot water going through the coffee grounds is given enough time to extract all those necessary flavors and compounds for a perfectly balanced cup.

Over-Extraction

Over-extraction occurs when too many soluble flavors are taken from the coffee beans and put into your cup. When the beans’ flavor is extracted too long, you will experience an unpleasant taste.

Over-extraction is easily done if your using a French press. If coffee is left in a French press after the plunger has been pushed down, the beans will continue to be extracted, thus producing a bitter cup of coffee. To avoid this, be sure to remove coffee immediately from the device. 

Although over-extraction dramatically impacts the taste of your coffee, the solution is relatively easy once you know exactly how to fix it.

Table comparing under and over extracted coffee. under extracted coffee tastes sour, salty, or soapy. Over extracted coffee tastes burnt, bitter, or metallic.

How to Know if Coffee is Under-Extracted and How to Fix it

Trial and error plus taste testing is the best way to determine if your coffee is under-extracted. Not everyone’s taste buds and preferences are going to be the same, so being able to experiment with your coffee is going to help you achieve that perfect tasting cup of coffee for you.

As mentioned in the introduction, some of the more common complaints of under-extracted coffee are sourness, saltiness, and sometimes a soapy-tasting drink.

Sour-Tasting Coffee

Coffee that tastes sour is typically the result of under-extraction. To fix this problem, you can try a couple of solutions.

First, let’s discuss the water used in the brewing process. You may need to use more water when brewing. If only using a small amount of water, the coffee is not allowed the entire time it needs for the full flavor to be extracted from the coffee grounds. For more details on the best coffee-to-water ratio, click here.

Another issue with your water, or possibly the coffee machine, is that the water is simply not hot enough. Warm water will have a hard time extracting all the good oils and flavors. What you end up getting is underdeveloped sour-tasting coffee. Read “Should I Brew Coffee with Boiling Water” for more details.

Now, on to grind size. If your grind size is too coarse, the hot water will pass through the grounds too fast and prevent the extraction of all the flavors, oils, and sugars.

Lastly, due to under-extraction, sour coffee could result from your coffee machine not functioning correctly. If the brew time is too short, the water does not have enough time to extract. You may be able to change the setting on the coffee pot, or you may have to consider purchasing a newer machine.

If you are tasting sourness when drinking your coffee, I suggest reading our full-length guide on What to do if Your Coffee Tastes Sour. 

Salty-Tasting Coffee

If you’re getting a salty taste when sipping your coffee, your coffee could be under-extracted. I say “could” because there are a couple of other things that may be the culprit.

Salty-tasting coffee may be due to using salty water, either from salt in your water lines or a faulty water softener system. You can read up on this more here.

If that salt taste is not due to the water your using, then it is most likely the result of under-extraction. Like the reasons for sourness, under-extraction is likely caused by insufficient water during brewing, the coffee grind being too coarse, or the coffee maker not functioning properly.

If your coffee is salty, I highly recommend reading our full article, “What to do if Your Coffee Tastes Salty.”

Soapy-Tasting Coffee

A possible culprit of soapy-tasting coffee is also under-extraction. Before we get into that, let’s take a quick look at other possible causes.

Soapiness can result from insufficient rinsing out the mug or brewing device, poorly roasted beans, low-quality water, or stale coffee beans. For more details on these possible causes, check out “What to do if Your Coffee Tastes Like Soap.”

If you don’t suspect any of those items caused your soapy-tasting coffee, then under-extraction is likely your problem.

How to Know if Coffee is Over-Extracted and How to Fix it

If your coffee is over-extracted, it will produce some harsher flavors, such as burnt, bitter, or even metallic. As you’ll see, there are other possible reasons why you may be experiencing these unfavorable tastes other than over-extraction. We’ll go over those briefly here as well.

Once again, this process will most likely take some trial and error.

Burnt-Tasting Coffee

Coffee that tastes burnt can be the result of several different things.

Probably the most common cause of burnt coffee are overly roasted beans. The darker the roast, the higher likelihood of those toasty, smoky flavors emerging, which increases the possibility of getting a burnt taste. Other issues include stale/old coffee beans or grounds, and your brewing device may need a good cleaning, tune-up, or replacement.

Okay, now that we got those out of the way, let’s talk about over-extraction and how that can produce burnt-tasting coffee. Over-extracted coffee occurs when the hot water runs through the coffee grounds too slowly, pulling out excess compounds and flavors, thus creating a not-so-pleasant taste.

Over-extraction is due to either the water being too hot, steeping for too long or the grind size you use being too fine. Experiment with your grind size. Refer to the chart below as a guide.

Table showing how fine you should grind your coffee beans. If your grind is too coarse, your coffee will be under extracted and if the grind is too fine, the coffee will be over-extracted.

If your coffee tastes burnt, read our complete guide on why this occurs and how to remedy the problem. 

Bitter-Tasting Coffee

Coffee bitterness typically comes down to using inferior coffee beans, or your brewing methods are flawed. Using high-quality arabica beans and ensuring that your grounded coffee is not over-extracted will prevent any bitterness in your coffee. 

If you are already using high-quality 100% arabica beans, like the ones we sell here at Taste The Latte, and still getting bitter coffee, then there’s an issue with how they are being extracted.

Here are some tips and tricks to avoid over-extraction.

  • Ensure your water isn’t too hot: Water between 195 and 205 degrees is perfect. You don’t want your water overboiling when pouring over the grounds. Let it sit for thirty to forty-five seconds to cool off.
  • Don’t steep coffee for too long for the bitter flavors to come through.
  • Experiment with the grind size you use. Depending on the brewing method, your grinds may be too coarse or too fine. If grounds are too coarse, it can lead to under-extraction, and if they are too fine, it can lead to over-extraction and bitterness. Read more on “How Fine Should I Grind My Coffee Beans?”
  • Don’t use too much water. When brewing, too much water can lead to bitterness because the excess water extracted from the coffee grounds is past the desired point. Read more on “What is the Best Coffee to Water Ratio?”
  • One last tip that doesn’t involve the extraction process is to ensure your brewing equipment is clean. If left unclean, old coffee residue or limescale buildup can produce bitterness or astringent flavors. Using a coffee maker cleaner or descaler is a great way to keep your devices clean and brew delicious tasting coffee every time. 

For further details on bitter-tasting coffee, check out “What to do if Your Coffee Tastes Bitter.”

Metallic-Tasting Coffee

There are a handful of reasons why your coffee tastes like metal, one of them being over-extraction. Before we get into that, let’s briefly touch on the other possible culprits.

This unpleasant taste could be caused by the water you are using. Unfortunately, not all water is equal in purity and taste. Tap water has extra minerals and dissolved solids that affect its taste, especially chlorine. Click here for more information on what type of water you should use. 

Other issues could be that the beans you are using are poorly roasted, your coffee machine has limescale buildup, or your machine is releasing various metals into your coffee (cited from a 2015 study). If you don’t suspect any of these issues are the cause, over-extraction is likely.

As with the other over-extraction problems, the same solutions will also be true here.

  1. Never use boiling water. Between 195 degrees and 205 degrees is just right.
  2. Don’t steep for too long. This is a common mistake when using a French Press.
  3. Adjust grind size to be a bit more coarse. Below is a table to help with grind size.
  4. Don’t use too much water. When brewing, using too much water can lead to bitterness because the excess water extracted from the coffee grounds is past the desired point. Read more on “What is the Best Coffee to Water Ratio?”

If your coffee tastes like metal, I highly suggest you read “What to do if Your Coffee Tastes Like Metal” to further explain the various solutions.

Final Thoughts

Under and over-extraction of coffee is a common issue in the coffee world. As a recap, under-extracted coffee will taste sour, salty, or soapy, and over-extracted coffee will taste burnt, bitter, or metallic. Now that you know what to look for, or should I say taste, you are that much closer to getting a perfectly smooth cup of coffee every time.

Brewing that perfect cup of coffee starts with having high-quality beans roasted to perfection every time. If you want the smoothest coffee, consider trying our coffee flavors. Click here to take a closer look at why our coffee is so unique!

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