A clean coffee grinder is essential for good coffee. Cleaning is even faster than with the espresso machine. The grinder cleaning shown here can be applied to all types of coffee and espresso grinders. Nevertheless, the manufacturer's instructions should be observed. In rare cases, cheaper espresso grinders may have different recommendations.
In this text, we explain cleaning with cleaning powder. You can get good cleaning powder from us in the shop, or from many other roasteries or grinder shops.
The new cleaning video linked below also shows how you can clean the grinding discs and the retention directly and manually with a cloth by opening the grinder.
Removing deposits and coffee oils
Like with the espresso machine, it's the coffee oils that settle unpleasantly. All the crevices of the grinder are popular spots, but so is the bean hopper. The darker the coffee is roasted, the more oils remain behind. And oils become rancid under the influence of oxygen. The main goal of cleaning is to remove oils and deposits from the surfaces of the grinding discs and unwanted crevices. After cleaning the grinder, the coffee tastes noticeably better, clearer and cleaner.
Retention
But oils are not the only problem. In many grinders, there are gaps where old coffee gets stuck. These gaps are called retention. The English-speaking world uses the term retention to refer to the coffee powder that remains behind. The coffee is already ground, but then doesn't come out of the grinder. Typical locations are, for example, the area in front of the flapper, in the discharge chute or around the grinding discs. The flapper serves to free the ground coffee from lumps, but can also have a blocking effect.
We distinguish between permanent and temporary retention. Permanent retention is filled once with ground coffee powder, but then doesn't exchange with each grinding. So if the grinder is not occasionally opened and cleaned, it becomes old in the grinder. Temporary retention contains coffee powder that is carried out of the grinder with the next grinding.
Clogged coffee behind the flapper of a Quamar M80e.
Why is retention a problem at all?
The coffee lies in ground form in the grinder. This exposes it to oxygen and it oxidizes faster - in other words: it gets old faster and tastes different after 30 minutes and noticeably worse after an hour. Unground, the coffee bean itself acts like a protective layer for the coffee. Grinding increases the surface area, which also accelerates aging. Every small particle is exposed to interaction with oxygen (and possibly light).
The coffee in temporary retention is carried out with each new grinding. Whether this portion of coffee beans has a clear or strong influence on taste depends on the time of the last grinding and the size of the retention. In our large test of over 24 espresso grinders for home use, we therefore also investigated retention in particular.
As an example: 2 grams of retention on a double espresso made with 18 grams of coffee play a smaller role. If retention holds 9 grams, then the espresso is made with half old coffee.
Permanent retention plays a different role. Although the settled powder is not released with each shot or doesn't have a direct impact on extraction, here we have coffee powder reacting with the environment, aging away in the grinder. This affects the hygiene in the grinder. Coffee powder doesn't usually mold, but it does create a rancid "atmosphere". The freshly ground coffee comes into contact with it and essentially rubs past the old coffee.
Does coffee in permanent retention have a sensory impact? Yes, and quite significantly! You can do this test yourself. Pull 18 grams of coffee and then clean the grinder. Follow our video if you have a G-Iota/DF64 or Eureka Mignon. If you have a different grinder, follow the manual, search for a guide on Youtube or write to us so we can make a video for you. After cleaning, pull another 18 grams. And now brew two double espressos. And then compare the results.
By the way: the size of temporary retention often also affects the consistency of the espresso grinder or coffee grinder. With some shots, more powder remains behind and with the following shots, more is dispensed.
Cleaning
- Remove and empty the bean hopper.
- Grind all remaining beans in the chute. If necessary, reattach the bean hopper for this, because some grinders won't grind otherwise.
- Add one heaping tablespoon of cleaning powder to the bean chute. Yes, many manufacturers recommend significantly more. But they also want to sell their cleaning powder. We believe that one tablespoon is sufficient. In the case of our cleaning powder, that's 10 to 15 grams.
- Grind the cleaning powder.
- Put the bean hopper back on.
- Grind a portion of coffee to remove any traces of cleaning powder.
You can learn more about this in our coffee courses at www.kaffeemacher.ch/akademie
Frequently asked questions about cleaning coffee and espresso grinders
How often should a coffee grinder be cleaned?
We recommend cleaning with grinder cleaner every two weeks. If the grinder is used frequently in a shared apartment or office, increase the frequency. In gastronomy, we recommend including grinder cleaning twice a week in the cleaning schedule.
Is cleaning with grinder cleaner necessary if I disassemble and clean the grinder?
Manual cleaning by opening the grinder and removing the coffee powder in the retention is more thorough than cleaning with grinder cleaner. So it can be done as an alternative.
