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Espresso Shot Troubleshooting

Five Senses CoffeeMitchell Fink 21 March 2011

Whether you’re working with coffee as a barista in a commercial setting or are a home enthusiast looking to start your day right, searching for that perfect shot is an elusive, ongoing challenge.

Here we’ll take a look at some common espresso-related problems and consider how to troubleshoot them.

Getting Started
Firstly, make sure your machine is dialed in to a solid espresso recipe. This is the single most important thing you can do to ensure consistent, delicious espresso. Find out how to dial in here: The Art of the Dial.

We like to start dialing in a coffee using a basic recipe of 22g of coffee in our portafilter, and extracting 44g out of our espresso machine.

Adjust the grind coarser or finer as necessary to have your shots pulling within 27-31 seconds. Make sure you use scales when dialing in!

Now that we’ve done that, on to the real troubleshooting!

Are my portafilter baskets actually designed to hold 22g of coffee? And how can I tell?
Upgrading to precision baskets is one of the best things you can do for your espresso, dollar for dollar. We recommend upgrading to a set of VST or Pullman Precision Baskets. These baskets are built to a tighter design standard, the holes in the bottom of these baskets are cut by lasers (so they are more evenly spaced) and the baskets are a more consistent size. This all translates to a better tasting espresso.

But I have 18g / 20g baskets? Will they work?
Many stock baskets are designed to hold 19 or 20g as standard, but baskets do come in a variety of sizes and you’re best off experimenting with a variety of doses to find what’s appropriate for your basket. You want your dose to be low enough that if you inserted the portafilter into the group head and removed it straight away, there would be no impression of the shower screen on the surface of the tamped coffee.

My puck turned into a coffee brick!
Once you’ve finished brewing a shot of coffee, the removed puck shouldn’t resemble a hard brick. If it does, then you’ve overfilled your basket. Remember that as we add water to coffee in the portafilter, it expands. The coffee needs enough room to expand without coming in to contact with the shower screen. Overfilled baskets are prone to causing channels and cause group heads to become dirtier. The coffee also runs through much faster which in turn leads to a bitter-tasting brew. Avoid this by dropping your dose a couple of grams and test the results.

My puck was all sloppy!
The other extreme of this problem is ‘the sloppy coffee puck’. With this issue, the dose is too small for the basket. When you brew the shot, the coffee expands with the addition of water, but the headroom between the tamped coffee in the portafilter and the group head shower screen is too great and the coffee never swells to an even shape, resulting in wet mush in place of the puck. This is far less of an issue than people think. But regardless, try increasing your dose to mitigate this issue.

Ok, so the ideal dose range for my basked is not 22g. What recipe do I use?
The size dose that is suitable for your portafilter basket will dictate what yield of espresso will be most appropriate in your brew recipe. We like espresso that follows a brew ratio of 1 part coffee to 2 parts water (i.e. 1:2).

So our 22g dose should have a 44g beverage weight, whilst a 19g dose would only have a 38g beverage weight. Same strength espresso, just different amounts of it. Easy!

My coffee is thin and weak with a fast-dissipating crema.
First check the roast date of your coffee. When coffee is roasted, it produces carbon dioxide as a byproduct of the roasting process. When your coffee is very fresh, you will see a lot of bubbles in the crema and a faster crema breakdown. Allow the beans a couple of days to rest and de-gas to obtain a more stable crema. However, keep in mind that coffee will become flatter and staler from 15 days past the roast date onwards. In addition, the longer you allow your coffee to de-gas, the more the flavour will change as well. As a starting point for better quality and a more stable crema, try brewing with coffee that’s between day seven and day 21 past roasting.

Shot Channelling.
Channelling is when the water from the espresso machine finds the path of least resistance through the puck of coffee. Several things can cause this, so it can be hard to diagnose exactly what is going wrong. The best way to observe if a shot is channelled is by using a naked portafilter but you can usually spot them regardless when a shot runs weak and watery at the very start of the pour, and has dramatically less crema than the other shots you’ve been pulling with the same coffee. You may sometimes also see the thin pour spiraling as it leaves the spouts.

To avoid this pesky issue, check on the following:

  • Ensure that the basket is not wet; a wet basket will encourage all the water to go around the puck rather than through it.
  • Distribute your coffee evenly prior to tamping, using our tamp distribution method.
  • Your tamp needs to be level. Otherwise, the water will take the path of least resistance which is through the thinnest part of your puck.
  • Don’t tap on the side of your portafilter after tamping. Tapping makes your puck look pretty, but risks breaking the seal of coffee with the edge of the basket.

Sour Tasting Coffee.
This can be caused by three key factors:

  1. Coffee that is a little too fresh. Try aging your coffee for a couple of extra days (never longer than three weeks though) to de-gas your coffee.
  2. You’re under extracting your coffee. Try grinding finer to slow down shot times.
  3. The brew water is a little cool. Make sure the temperature of your machine is above 94 degrees Celsius.

Bitter Tasting Coffee.
Overly bitter coffee can also be caused by three main factors:

  1. Dirty equipment! Check that your portafilters and group heads aren’t dirty. Clean everything and wipe down the insides so they’re clean of any coffee residue. We recommend doing this every 30-60 minutes during service.
  2. You’re over-extracting your coffee. Try grinding coarser to speed up shot times.
  3. The brew temperature is too hot. Make sure the temperature of your machine is below 96 degrees Celsius.

As you can see, most of these problems can be easily avoided by following a brew recipe, using fresh coffee and employing the appropriate technique when preparing your espresso.

If you’re still struggling, come and visit us at one of our Barista Academies. Our classes cover all the content mentioned here (but in far greater detail), with plenty of time for practical demonstrations, exercises and guidance.

If all else fails, give us or your local technician a call. When the problem goes beyond general troubleshooting, your technician will be able to make a more detailed assessment of things such as your pressure gauge and grinder burrs. It’s all in the pursuit of great coffee!

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