adjusting your grinder

Fine Tuning Your Espresso Extraction

Getting your espresso extracting just right is an ongoing battle, one that all baristas know well. As you know, there are more than a handful of variables to take into account when troubleshooting. We have put together a comprehensive list of extraction problems you’re likely to run into and some of the reasons why they occur to help you get on the way to perfect coffee every time.

 

Thin and watery extraction 

If you’re extraction is lacking that luscious thick viscosity that you see in photos there may be a few things to double check before adjusting your grind consistency.

  • Ensure that your coffee is fresh, typically your coffee beans are best used several days after roasting for the best flavor, but remember they will go stale about three weeks after their roasting date.
  • Make sure that you are pulling the correct volume of liquid for your coffee shots. Depending on whether you use automatically programmed volumetric buttons or pull your shots manually you will want to check that you’re getting 30mls of liquid for each shot. Running more water through the same amount of coffee will result in a thin and watery shot of espresso.
  • Check the temperature and pressure of your coffee machine, this is more common in smaller home machines that share a boiler for coffee brewing as well as steam/hot water. You’ll need the water heat to be around 95C to extract the coffee oils from your grind.
  • Finally, it may be that you’re coffee grind is too coarse and the water is running through it too quickly to pick up the oils from the coffee.

 

Bubbly extraction and no crema

You may notice that your extraction is very bubbly and that the crema dissipates very quickly, this is likely due to excess carbon dioxide.

  • Be sure that you’re not using coffee that has only just been roasted. When coffee beans are roasted they produce carbon dioxide as part of the process, give them a few days to de-gas and reach their optimum flavor.
  • Freshly roasted coffee (first few days after roasting) can lead to an odd sour taste.
  • Consider where you are storing your coffee, remember that it must be kept as air tight as possible and stored in a cool, dry place. Coffee kept in the sun, an open container or in the refrigerator will cause your coffee to break down.

 

Water channeling and cracks in the coffee puck

Channeling can cause all sorts of problems with your espresso extraction, channeling occurs when your tamp is uneven, when the coffee puck has come away from the portafilter basket, or if the basket gets knocked and causes cracks or fissures in the puck.

  • Make it a habit NOT to tap your portafilter with your coffee tamp, the harsh knock of metal on metal is more than enough to shake the coffee puck away from the basket or cause channels to appear.
  • Tamping unevenly will cause water to pool predominantly in one area and take the path of least resistance, causing uneven shots and disrupting the taste where some of the coffee grind has been over extracted and some not at all.

 

Harsh, bitter and burnt coffee

It can be very frustrating when your coffee shot looks fine but is bitter to the taste, and its always embarrassing when a customer comes back to you with a complaint about your coffee tasting burnt!

  • Make sure throughout the day you are timing your coffee shots, aim to extract your coffee between 25 and 30 seconds as a guide.
  • We encourage you to taste test your shots to get the most out of the particular blend of coffee you are using, light roasts usually taste smoother with a slightly longer extraction to eliminate the extra acidity where as medium and dark roasts can be extracted a little quicker.
  • If your shots are starting to run for too long the water is running through spent coffee and starts to take on the bitter roasted flavour of the husk of the coffee bean.
  • The ambient temperature around the coffee grinder also causes the beans to expand or contract slightly which will change the consistency of the coffee grind so keep an eye on your shots when temperatures are changing!

 

Many of these common problems can be avoided by a little bit of diligence and observation on your part, just make sure you use good quality, fresh coffee beans, correct technique when preparing the basket and checking your extractions over the course of the day.

If there are any particularly difficult problems you’re facing, its worth asking your technician or supplier to take a look or shoot us through an email, we’re always happy to help!

About The Author

Luke is a barista trainer at HG Coffee School and is passionate about training new students in the art of coffee!

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