Ask any chef, line-cook, or grill maestro and they’ll all tell you the same thing: your knife is the most important tool if you’re adding heat to food. And before you go clicking elsewhere, yes, you are looking at the article that tells you why a high-quality grinder is important. So how does this tie into that whole chef’s knife business from the top of the article?
When you sauté chopped onions, if you’ve cut most of the onion to a similar size (similar surface area) but some bits are smaller or thinner, I'm sure you've noticed those thinner cuts turn into shriveled bits of disappointment. Or if you’ve grilled steaks that are cut poorly (i.e. the cut leaves a larger surface area of meat compared to others), the larger steak cooks well but the smaller steak ends up dry and chewy.
In both cases, inconsistent surface area (be it an onion, a steak, or even coffee grounds) equals heat applied to the onions/steak/coffee inconsistently. If your goal is the kind of slow-sauteed onion in French onion soup, but your chop is off, your cup of soup has bits that are vegetal, sharp, and radically different from the rest of the dish. If you apply too much heat to the steak, you’ll get a dry, leathery bootstrap to chew on. If you let too much hot water pass through the coffee grounds, you’ll pull out more than just the desired solubles and end up with an over-extracted, acidic battery-licking experience.
Let’s turn our attention to the science of solubles available in coffee and why grind is important to achieve optimal flavor.
Depending on how long you’re going to let water be in contact with your grounds (and what temperature your water is as that extraction happens), you’ll want more or less surface area for those grounds. If you’re going for the low and slow method (think cold brew; low temp and longer extraction time) you’ll need less surface area. If you’re pulling some wicked ‘spro (brah) you’d best have some high surface area because you’ve got hot water and around 30 seconds to pull that shot.
In any case, that surface area had better be consistent . If it’s not, the water dosage you’ve used is inconsistently applied. Things get out of hand in a hurry if your grounds aren’t consistent.
In the world of coffee gear, it’s easy to go over-budget and buy every goose-neck, restricting water kettle or the fanciest scale and thermapen available. If you couldn’t tell by this point in the article, I’d highly suggest going all-in and maintain a high-quality grinder. That’s not to say that volume of water, temp, or extraction time aren’t important, but it is to say that the consistency of grind is paramount.
Put differently, you can have that golden ratio of 16g of water to every gram of coffee, but if you’ve ground your coffee with a blade grinder (or even a worn-down burr grinder) then your cup of coffee is going to be--at best--a balance of overly acidic and overwhelmingly basic sorrow (the bitterness your tasting comes from your tears of remorse as you wail, “Why, dear God, WHY?!”).
Put to a positive spin, when your grind is on-point then your water pulls out the the desired solubles, and each granule sings out the full-throated volume of its potential into the cup.
Having a great grinder is a beautiful thing, and you’ll be glad you made the update every morning.