We’ve all been there, you weigh your beans, dose and grind, then flip on your espresso machine, then what you get is a sour mess. So what’s causing this? We’re here to help!

The Dose

The first place that your espresso shot can go wrong is the dose. Using too few beans can result in a weak, thin, and easy to under-extract shot, which can give you that sour taste.

For this reason we recommend starting with a 2:1 ratio of water to beans. This will set you up for a successful shot.

The Grind

The next key point in the brewing process is a proper grind setting. If your coffee is sour is suggests that it’s being under-extracted. The best way to counteract this is by tightening up your grind. This will restrict water flow and help improve extraction.

Just remember that going too fine can over-constrict water flow and lead to a bitter shot instead of sour, which is a similar, if flipped issue. This is why we recommend small adjustments as you make changes to your grind settings.

The Tamp

Tamping is one of the trickier parts of the process to get right. You need to apply around 25 lbs of pressure to the tamper to get a proper tamp, but this is a really hard thing to judge. To help, you can use a calibrated tamper or a tamper like the Eureka Easy Tamper.

Before you tamp, you should also ensure the grounds are properly distributed in your portafilter. This can be done with some light taps on the edge of the portafilter, or with a more precise distribution tool (some of which even double as adjustable tampers).

By getting the proper tamp you help to provide that restriction of water flow needed for proper extraction, with a light tamp and uneven grounds you can cause channeling and under-extraction, whereas to heavy of a tamp can lead to a bitter, over-extracted shot.

The Pull

The last piece of the puzzle is pulling your water through the portafilter, but this involves a few different factors. For starters, you need to make sure your water is the correct temperature. Your espresso machine should regulate this, but if you have a cheap machine it’s possible that its heating element won’t be up to the task of brewing a proper shot.

You also need to ensure that the machine’s pump is pushing water through at a proper rate, which is also down to machine performance. It’s rare that temp/pump flow are the causes of a sour shot and you should be able to easily address it if it’s the machine.

You’ll want to measure both the volume of your shot (either with a scale or a demarked shot glass) to make sure you’re pulling the right amount of water, and you’ll also want to make sure that your shot time is in the 20-30 second range. If your shot “dumps” into the shot glass in under 20 seconds then you likely need to tighten up your grind or tamp, as it will result in a sour shot.

Pressurized Portafilters

You may find that you just can’t get your grinder to grind fine enough to produce a proper shot in an unpressurized portafilter. Many machines also come with pressurized baskets that help provide the additional flow restriction needed to ensure proper extraction. If your grinder can’t grind tight enough for a good shot then you should consider using a pressurized basket if you have one!

If you're looking for more details and to see this advice in action be sure to check out the video below! Let us know in the comments if you found this article helpful too!