It’s all in the grind-Coffee extraction explained
9 May 2016
Grinder adjustment is one of the key elements in getting a good coffee extraction in espresso coffee and needs constant attention and focus. How fine or how coarse you set your grinder will be the main determinant of your extraction quality. A good extraction time is to get around 30 mls of coffee in around 30 seconds. Measure your extraction time from the moment you start your coffee extraction to the time the shot finishes. Less than 15 seconds and your coffee will taste thin and bitter. For most coffee once you get out over 35 seconds a burnt taint can run through your cup.
I have seen heated debate over extraction times amongst coffee enthusiasts and keep in mind the ideal extraction time will vary with coffee types but as a rule of thumb 30mls in 30 seconds is a good one.
Steps for grinder adjustment.
Step 1. Time your current shot using a stopwatch.
Step 2. Determine if you need to slow the shot down (by adjusting finer) or speed the shot up (by adjusting coarser). Remember to check the dosage (how much coffee you put in the filter basket of the group handle) as this will also slow down or speed up the extraction time if it is over or under dosed.
Step 3. Adjust your grinder
Most grinders go finer if you turn the adjusting ring anti clockwise and coarser if you clockwise.
Step 4. Wait.
There is always a lag between adjusting your grinder and seeing the full effect of the change. On bigger commercial grinders this can be as much as 6-8 shots of coffee.
Step 5. Retime the shot.
Get your stop watch out and time the shot again. If it is still running faster or slower than you would like then go back to step 3 and adjust your grinder. Small changes are best.
Mastering grinder adjustment can take some time but the rewards for those that get it are in the cup!
Once you have this worked out you can move up to weighing shot, dose and yield, as well as monitoring shot times.