We've all asked this question before - why does my espresso taste so bitter? In fact, some people think espresso is just a bitter kind of coffee. Even worse, some people just think all coffee is bitter no matter what! We're happy to tell you this is not the case. While coffee can have a strong flavor with a hint of dark chocolatey bitterness, it shouldn't be overpowering. Espresso in particular should be more smooth and sweet than bitter. It's still a rich, strong flavor, but it should be pleasant to most palates. So what's up with your bitter shot? Well, it could be a few things.
Dirty Equipment
The first thing you need to keep in mind is that your espresso machine and grinder need to be kept cleaned and maintained. While you don't need to clean them daily, you do need to keep them clean based on your usage. If you are pulling 3-4 shots per day then you should be backflushing with a product like Cafiza once every week or so. You'll also need to use a brush to keep the shower cleaned up, use a clean portafilter, and keep up with an a descaling depending on your machine and usage. In some cases you may also need to replace your brew gasket or shower screen from time to time as well. On the grinder side, it's important to run a product like Grindz through every couple of months (or more depending on your usage). a cleaner like this will keep the chamber clean and help flush stale coffee. You'll also want to disassemble the grinder to clean the burrs once in a while, again depending on use. While dirty equipment usually results in a stale taste more than a bitter one, the oil build up can cause that bitterness, as can mineral build. By cleaning and maintaining your equipment properly you extend its life and eliminate poor maintenance as a factor when diagnosing flavor issues.
Over-Extraction
The primary cause of bitter espresso shots is over-extraction. Coffee and espresso extraction is a delicate balance. You want to bond the hot water being pressed through the puck of grounds to the coffee molecules, creating your delicious shot. This process is called extraction. Over-extraction happens when the water bonds "too much" with the coffee. There are multiple ways this can occur, but most commonly it's due to poor flow through the espresso puck. This usually happens because the grounds are too fine and restrictive. This restrictiveness can also come from a tamp that's too tight. You'll want to apply an even 30lbs of pressure to tamp your pucks, that way you don't get bitter over-extraction or sour under-extraction. You can also end up with over-extraction if your water is too hot. High water temperatures can also burn the coffee, leading to another cause of bitterness. Scorching coffee can also happen if it's left on a burner for too long or overheated.
How Do I Fix My Shots?
To fix a bitter shot the first thing you'll want to do is remove as many easily controlled variables as possible. Water temperature shouldn't be an issue on a decent espresso machine, but if you do have a PID controller then check to make sure it's set at 200 degrees Fahrenheit. Next, make sure you get your tamping right, you can get a calibrated tamper if you need extra help. Once you've done all of this you'll want to make sure your grinder is properly set. If your shots are on the bitter side, make a minor adjustment to a coarser setting. Try a shot like this, and aim for a shot time of 20-30 seconds. If the shot takes much longer than 30 seconds, it'll probably be bitter, and you'll want to make it a bit coarser. If the shot is too fast then it might be sour, which means you went too coarse. You'll likely need to perform this process when you change beans, but you'll get better at it! Different beans will need different settings to get the best results. Some beans can be harder to work with than others, which is why we recommend a balanced blend like Tony's Crew Brew to learn how dial in. By carefully dialing your grinder settings you can achieve that perfect tasting shot!