Why is My Coffee Bitter?

Mistobox Coffee Roasters with coffee beans varying in roast level

It’s impossible to burn your coffee. Coffee is roasted at extremely high temperatures, and 200-degree water isn't going to cook it further. If you’re complaining of burnt-tasting, bitter coffee, we’ve got a few tricks up our sleeve to fix the problem. Let’s explore why your coffee tastes so bad as we look at roast level, extraction, grind size, brew temperature, and machine upkeep. 

Dark Roasts

First, coffee is naturally bitter. Just because a coffee tastes ashy, smokey, or burnt doesn’t mean it’s a bad coffee. It could mean that you just don’t like that coffee. These richer notes stand out in some coffees more than others depending on the varietal, where it’s grown, how it’s processed and how it’s roasted. Typically coffees with these notes will be roasted darker to accentuate these flavors as they are desired by many. 

As a coffee is roasted and heat continues to break down sugars, those sugars eventually carbonize and start to move into that bitter/burnt region, which for some is a good thing. At this point in the roasting process, sometimes that can look like a black, oily bean, and others can be a milk chocolate color. The longer a coffee is roasted, the less dense and more soluble they become, making them at higher risk of over-extracting while brewing which is another reason why coffee can taste bitter. 


As you introduce water to coffee, extraction occurs. Different compounds in the coffee extract more easily than others. As a shot pulls, the acids and fats are the first to extract. These give your shot juiciness, body, and clarity. Sugars will pull next, softening the coffee and rounding it out. Lastly, plant fibers will extract from the coffee, which can cause it to taste astringent and bitter. Shorten or lengthen your brew time to adjust how much you extract. The longer a shot runs, the more bitterness will come through. This is often why shorter, ristretto-type shots are recommended for darker roasted coffee. Another helpful tip is to dilute your espresso in some hot water when tasting — sort of like an Americano. Our palates perceive strength as bitterness. It’s possible your shot may be too strong and reading as bitter. 

Grind Size

Your grind size plays a role in extraction. The finer the grind, the more surface area, the easier it is for water to access the coffee and extract things from it. So, finer grinds will extract more than coarser grinds if brewed for the same amount of time. As we discussed earlier, dark roasts are more soluble, so you may need them coarser to not over-extract. 


If your machine allows, adjusting your brew temperature can help you tremendously. The hotter the water, the more you will extract. If your coffee is tasting bitter, try lowering the temperature to extract less. A good temperature range for espresso is between 195-205 degrees Fahrenheit. If you’re using a darker roast, the 195-200 range might be a good place to start. 


Lastly, cleaning. If you’ve tried everything above and your coffee still isn’t tasting great, make sure your machine is clean, and there isn’t any coffee oil or grounds coating the portafilter, basket, or group head. Run a backflush cycle with detergent, use hot water and a rag and make sure things are clean! 

How to clean your espresso machine

If your espresso isn’t tasting quite right and you’ve tried all the tips above, switch up coffees and try something new. We are here if you have any questions! Leave your thoughts and comments below or email us at hello@clivecoffee.com