Posted by Matthew on 2/18/2022 to Coffee Education
Watching a barista grind, tamp, load and then let superheated water do its whistling work is something to look forward to. The rhythm, smell and sound of the espresso-making ritual forms a kind of dance that’s a pleasure to experience, as well as a lovely prelude to a delicious drink.
One thing most of us know is just how fine espresso grind is. And for those of us who like espresso-based beverages, coffee dust equals coffee gold. There’s a reason why the coffee for your café-bought cuppa is fresh-ground right before brewing: to get the most from its oils and aromatics. That’s because they evaporate quickly and are susceptible to oxidation, a process that accelerates when whole beans are ground into tiny pieces that present many times more surface area.
Grind for your brew
Aficionados know that grind affects flavour. While espresso is ground to the consistency of powder, French press and cold brewing call for coarse grinds that are closer in consistency to cornmeal. Because those coffee grounds are bigger, a quick jet of super-heated water isn’t enough; they need more brew time. French press grounds are steeped in piping hot water for around four minutes, while cold brew coffee is steeped overnight. Brewing takes longer, but because the grinds are coarser they slow down extraction and diminish the risk of over-brewing.
With filter-based brew methods, like the pour over, brew time depends on how long it takes for the water to filter through the grounds. A coarse grind won’t take long, but you’re sure to get a super-weak cup of coffee. Brew time is one reason why coffee-shop pour overs tend to cost more than an Americano: they use medium-fine grinds and take several minutes and lots of pouring to complete.
For most stovetop espresso pots as well as Chemex and drip coffee makers, a medium grind is what you’ll need. Match your grind size to your method and you’ll get a nice, balanced cup of coffee. Too fine a grind can make your coffee over-potent and bitter, while too coarse a grind yields a weak cup that’s more salty than sweet.
Not all grinders are made equal!
Unless you’re grinding your coffee with a mortar and pestle, , you’re almost definitely using either a blade grinder or a burr grinder. Blade grinders are prevalent since they’re fast and cheap, but they have a downside. As the blades whir around at high speed, they slash beans into uneven chunks. Even with a coarse grind, you’re bound to get some fines mixed in with larger chunks, or larger chunks mixed in with your fines in the case of espresso. That can result in a flavour that is a bit off-target. Blade grinders also heat the coffee as they grind, which accelerates the evaporation of aromatics.
Burr grinders (or at least sharp burr grinders) deliver a much more consistent grind. Think of two steel gears turning close to each other. What gets caught between them is broken up into consistent chunks. Shorten up the distance and you’ll get an espresso grind. Increase it and you can go right up to French press. The burrs turn much more slowly than blades, so they don’t heat your beans—another plus!
If you want to refine your brewing process to the point where you get a delicious cup of coffee every time, start with high-quality, freshly-roasted coffee. Then choose the right grind size for your brew method and, ideally, invest in a good burr grinder—either plug-in or manual. It will serve you well for years to come.