What Can Cause Espresso To Taste Bitter, Sour, or Burnt?

If you have ever been severely disappointed with how your espresso tasted, you must have immediately wondered what could have possibly gone wrong. As the cause of disappointment can range from your espresso tasting too sour, all the way to your espresso tasting bitter or even burnt, it’s not exactly easy to pinpoint the issue at first look.

Especially considering that the brewing process of an espresso shot is largely automated, consistency between brews should be present for the most part. While it’s easy to blame your espresso machine for this at first, let’s not forget that there is also a small amount of manual work involved, which is more than likely the actual part of the process where things went wrong as the chance of your espresso maker failing is quite slim.

So, what can cause your espresso to taste bitter, sour, or burnt?

Espresso tasting sour is caused by under-extraction of coffee, whereas espresso tasting bitter or burnt is caused by over-extraction. While there is a multitude of reasons behind the under or over-extraction of coffee grounds, we can narrow the reasons down to a certain few in the case of espresso.

As factors such as brewing time and brewing temperature are automatically adjusted by the espresso maker, the reasons that immediately come to mind are related to the coffee-to-water ratio, grind size of the coffee grounds, and the amount of force that is used for tamping the coffee.

Why Does My Espresso Taste Sour?

To start, let’s talk about the reasons that can cause your espresso to taste sour.

You’re Tamping Too Lightly

Let’s start with the factor that is overlooked most of the time, which is the force that is used to tamp coffee grounds. It’s not mentioned often, but tamping your coffee grounds too lightly can easily under-extraction, causing your coffee to taste sour.

As lightly tamped coffee grounds will have plenty of space between them for water to flow through, coffee grounds won’t be staying in contact with water for the required amount of time before the coffee makes its way out of the portafilter into your cup.

You’re Grinding Too Coarse

We can’t stress the importance of grind size enough. This is another factor that isn’t thought about much, but it does have quite an impact on the extraction level of your coffee grounds. When the grind size is too coarse, the surface area of the coffee grounds is decreased, and the gaps between them are increased.

This causes grinds to be under-extracted as water finds ways of going through the filter without coming into contact with all of the coffee grounds for the required amount of time.

You’re Adding Too Much Coffee

While this is one of the less-faced problems due to the portafilter only being able to take in so much coffee, you can indeed overfill your portafilter if you aren’t careful. 

Considering that your espresso maker brews your espresso with a set amount of water, adding too much coffee will throw the coffee-to-water ratio off. While you may think that adding too much coffee should cause your espresso to taste bitter instead, it’s actually the opposite due to how extraction works.

Since the amount of water stays the same and the number of coffee increases, the extraction level of every single coffee ground drops, causing only the sour components of the coffee to be extracted.

Why Does My Espresso Taste Bitter?

Now that we have gone over the reasons that can cause your espresso to turn sour, it’s time to dive into the opposite side of the spectrum.

You’re Tamping Too Hard

It’s easy to believe that there is no such thing as tamping too hard, as most of us who are new to brewing espresso use a high amount of force for the tamping process to ensure that the coffee grounds stay tightly in the portafilter.

In reality, what this does is pack the coffee grounds so tight that water has a hard time making its way through the filter, effectively causing coffee grounds to stay in contact with water for way too long.

When water stays in coffee grounds for too long, over-extraction of the grounds occurs where the unwanted components of coffee start being extracted, giving a bitter taste to your espresso.

You’re Grinding Too Fine

A lot of people fall into the trap of grinding their coffee beans as much as they can due to espresso requiring one of the finest grind sizes, thinking that it’s practically impossible for a certain grind size to be too fine for espresso.

While the grind size that is required for espresso is indeed quite fine, it’s possible to grind coffee in a way that’s even finer than what is required for espresso. This grind size is often used for Turkish coffee, where coffee grounds look similar to confectioner’s sugar.

Using a grind size that is too fine increases the surface area of your coffee grounds way too much, once again causing water to stay in contact with the coffee grounds for way longer than necessary. As you can imagine, this causes over-extraction of the coffee grounds, where bitter components find their way into your cup.

You’re Not Adding Enough Coffee

While you should be getting the coffee amount right most of the time with the size of the portafilter acting as a guide, it wouldn’t hurt to measure your coffee the next time you’re brewing.

Not adding enough coffee will automatically cause your coffee grounds to be over-extracted due to the amount of water being overwhelming and turn your espresso into a bitter mess. 

By simply using a kitchen scale next time you’re brewing, try comparing the amount of coffee you usually use to the amount you have just measured. This way, you should be able to see whether you’re using too little coffee.

Why Does My Espresso Taste Burnt?

Espresso tasting burnt is also a result of over-extraction, similar to espresso tasting bitter. 

As there are levels to how over-extracted coffee grounds can be, a drastic amount of over-extraction can indeed cause your espresso to taste completely burnt.

Since we have already listed the reasons behind over-extraction in the previous section, you can simply refer to that section to find out what you should be doing to prevent over-extraction the next time you are brewing espresso.

Why Is There No Crema on My Espresso?

While the primary reason for the lack of crema on your espresso is stale coffee beans, factors such as grind size are also known to cause problems in this department.

Our first recommendation would be to ensure that you’re using fresh coffee beans that are freshly ground to brew. As improper storage can cause coffee beans to go stale quite easily, it’s a good idea to factor freshness out of the equation before moving on to other things.

If the problem still persists, ensure that you’re using the correct grind size. Since this may not be apparent at first, a good way of checking is to buy pre-ground coffee and see if the problem is still happening. If it’s not, you’re most likely facing a grinder-related problem.

In the case that the problem is still going on, check the other factors that may affect the quality of your brews, such as the amount of coffee and the force you use to tamp your coffee.


As the reasons behind your espresso tasting sour, bitter, or burnt are mostly caused in the preparation phase of the brewing process, you should be able to find the root of the issue by paying close attention to things such as grind size, coffee-to-water ratio, and how hard you tamp.

Remember that each of these factors can have an impact on your espresso, and show them an equal amount of care to ensure that everything goes smoothly.

Have a great day, and enjoy your coffee!