Why Your Espresso Tastes Bitter, Burnt or Sour

Brewing espresso is as much an art as it is a science, and sometimes just one simple mistake can ruin the experience. If your fresh espresso tastes bitter, burnt, or sour, you might be dealing with a brewing problem. In this article, you’ll learn what causes these unpleasant flavors and how to fix the problem.

What is Astringency?

Astringency describes bitterness and acidity, usually in a beverage such as coffee or tea. A cup of coffee’s astringency can be altered through various means, but a highly astringent cup will usually taste harsh and undesirable. Astringency also refers to the sensation of dryness in the mouth caused by drinking it.

The sensation of astringency in coffee, for example, is often desired in limited amounts. When you drink espresso, you want a little of that bitterness and strength for the bold flavor, but you don’t want it so astringent that you pucker your lips. Astringency is a completely natural property of coffee and can’t be totally avoided, but when it becomes overwhelming, it’s time to make a change.

Signs Your Espresso Isn’t Quite Right

There are some surefire methods to test if your espresso isn’t being brewed properly. The first thing you’ll want to watch out for is an unpleasant taste. This can take many forms, including bitterness, a burnt aftertaste, or sourness. There are several causes that could be responsible for this.

Quality of Grounds

Before anything else, check the quality of your coffee grounds. The term espresso actually refers to the roast itself, not the type of grounds – so you can use any grounds you like. That being said, buying higher quality coffee will naturally improve your brew.

If you tend to purchase whatever is affordable when it comes to coffee, consider changing it up and investing in some higher quality beans instead. Make sure you can identify their source – if you’re not sure where the coffee comes from, it’s probably poor quality.

Stale Coffee

Although many people don’t know this or take it into account, coffee can absolutely go stale. Coffee grounds stored in airtight container in a cool, dark location will last up to 3-5 months after opening the package. However, exposure to oxygen and other elements can shorten that lifespan.

If you brew espresso using stale grounds, you may notice a sour or otherwise unpleasant taste. The coffee may taste “flat” and lifeless, lacking its usual robust flavor profile. If you struggle with stale grounds in your pantry, it might be advisable to purchase your coffee in smaller amounts.


The ideal cup of espresso should be brewed at a temperature between 195-205℉. If you brew at a higher temperature than that, you risk breaking down the tannins present in your coffee, which creates a bitter taste.

You should also only drink your espresso when it’s hot and fresh. As soon as your coffee is finished brewing, there begins a “cooldown timer” where your coffee starts to slowly develop a duller taste. That’s why drinking old or reheated coffee is such a negative experience. For the best taste possible, you should aim to drink your espresso within ten minutes of brewing.

Over Extraction

Another potential cause for bitter espresso is over extraction of the grounds. If you’ve ever wondered why people don’t grind coffee into a fine powder to brew it, this is why. Coffee actually tastes best when it’s brewed at a balance between over and under extraction of its flavor.

When you brew espresso, the grounds don’t completely absorb every bit of water during the process. Coffee beans have a complex chemical structure, and when they’re fully saturated during the brewing process, you get what’s called over extraction. This means that too much of the coffee’s flavor has actually made it into your cup.

It sounds counter-intuitive, but over extraction does more harm than good for the flavor of your coffee. Over extraction produces a highly bitter, harsh tasting coffee. Nine times out of ten, over extraction is caused by brewing for too long. You want to be careful about extracting just the right amount of flavor.

Dirty Equipment

If your coffee tastes more burnt than bitter, your brewing equipment is likely the culprit. Check the temperature to ensure that you aren’t burning any residual coffee in your machine. Sometimes, when your equipment gets overheated, it can burn old coffee into the next batch.

If you use a moka pot to brew your espresso, make sure you’re properly maintaining it. Moka pots are notorious for accumulating burnt coffee residue along their interior. Descaling your machine properly can also prevent that buildup.

How to Fix It

If you’re left with a bitter tasting cup of espresso, you have a few options left that might be able to save it. Firstly, adding extras such as cream and sugar can do a lot to bring the flavor back. Try adding more cream than usual if you notice the flavor is particularly rough.

Despite how it sounds, adding a pinch of salt to your coffee can actually counteract its bitterness. When you drink coffee, your taste buds react chemically with the structure of your beverage. The addition of a tiny bit of salt actually stimulates your taste buds in a unique way and takes the edge off that bitter flavor.

If you still end up brewing flat, bitter, or burnt coffee, you might want to consider simply changing your brewing method. There are many ways you can make espresso at home, including:

  • French press
  • Aeropress
  • Moka pot
  • Manual pull machines

Sometimes you just have to explore different options and find what works best for you and your own personal preferences.

Better Espresso

Espresso should taste strong, bold, and intense, but not harsh or bitter. Although repeated bad batches can become discouraging, don’t give up! If you find yourself struggling to brew it the way you like, take the time to explore different methods and expert tips. There’s an espresso style out there for everyone, and you just have to find yours.