Grind Retention (and why you should care).
Your alarm goes off. You get up, walk downstairs and turn on the kettle. You weigh your beans and place them in your grinder. You flick "on" and your grinder starts humming it's morning tune. All your beans are ground and you turn off your grinder. Time to brew. Each coffee bean you placed in your grinder is now sitting in your brewer freshly ground.
Or are they?
Grind retention is a conversation that gets any coffee enthusiast intrigued. The science and engineering behind a grinder to dispense the same (or close to the same) amount of coffee that you put into the grinder is fascinating!
So what is Grind Retention?
Grind retention is a phrase that is used when discussing the merits of different grinders. As coffee is ground, there are spaces in the burr chamber where your ground coffee can rest without making it out of the grinder.
Why does it happen?
Every grinder has a unique design. Each manufacture creates a grinder with a few goals in mind. Things like grind quality, static, speed and noise are large factors in creating a quality grinder. All of these features can lead to designs with nooks and spaces in the grind path of a grinder where coffee can get stuck until more coffee is ground.
Some grinders even have an intentional design to retain grounds and have grind retention. This can ultimately reduce static and improve flow. There is nothing worse than static coffee flying across your counter. And in a cafe, this is a convenient feature.
But at home this is not always the best idea. A Cafe may create hundreds of drinks in a short amount of time. At home you may be drinking just a few.
Why should I care?
As coffee sits in the burr chamber it looses freshness, aromatics and overall flavour. Secondly, this retention also means that an adjustment in grind size does not have an immediate effect, with some coffee from the previous setting making their way into your current dose.
If you're reading this you probably want the best flavour in your cup of coffee. Grind retention is something you should care about!
So what do I do?
The issue of grind retention can be solved by a quick purge before your first shot of the day. If your grinder is sitting for more than thirty minutes between grinds, give it a quick purge! A little tap of the button and you're good to go! The greater the grinders retention, the greater the need to purge more grounds.
What if you want to single dose? Well, then you're in the right place! Single dosing is most often the way to go in a home brewing setting. We'll save that conversation for another time.
But for grinders, this is where the conversation becomes very tricky. For those that wish to single-dose their beans, some grinders work exceptionally well, however, grind retention can be challenging in certain models. If you aim to single dose then a grinder’s retention is likely among the greatest determining factors in whether or not it will suit your needs.
Regardless of if you are brewing filter coffee or Espresso, get in the habit of purging the grinder of old grounds before grinding your dose. Even for grinders like the Baratza Encore, it's a good habit to run a few beans through before grinding your dose.
I've listed a few great options for low grind retention for espresso below. For all your other home brewing needs, be sure to check out Brewathome.ca.
Brew At Home,
Low Retention Grinder Recommendations:
Baratta Sette 270
The Sette 270 has almost no space between it's burrs and the portafilter for coffee grounds to hide. It has a unique straight-thru design that makes it one of the best espresso grinders for retention. It's also one the best bang for buck espresso grinders out there.
Eureka Mignon Specialita
As you can see in the photos shown, the Specialita’s small and neatly designed burr chamber leaves little room for grounds to collect. This makes it a very low retention grinder considering it uses flat burrs. According to Clive Coffee, it retains about 1.5g of grounds.
The Niche Zero is another conical burr grinder, but a great one at that. It uses massive 63mm conical burrs to grind straight thru to its convenient metal catcher. Its design has zero retention in it's focus, with its name, "Niche Zero", proving this point. The fact that this grinder ditched the conventional hopper for a modern lid with a bean dish is something I find fantastic. Though, its price is the highest of the three. Regardless, this is one worth looking at.