What is Extraction?
Coffee extraction is the process by which water-soluble particulates are dissolved and “extracted” from the grinds into water. Or, in plain English, “extraction is everything that water takes from the coffee beans” (thanks Matt Perger).
When a green coffee bean is roasted, the naturally occurring nutrients in it break down into sugars, minerals, and oils, all while the bean’s cellulous structure expands to accommodate the gas being released by the chemical reactions inside. But because the bean’s structure is so rigid, it still holds on tightly to all of the flavor and caffeine pent up inside. We grind our coffee to break down this structure (, increasing the surface area, relative to mass, so that water may pass through the coffee more easily) so that we can then extract all of the goodness that nature (and your local craft roaster) have so generously given to us.
Why does Extraction Matter?
*Extraction is everything.* Say it out loud to make sure that it sticks. “Extraction. Is. Everything.” Extraction is the single most important factor in creating a cup of coffee that someone will actually want to drink. A balanced and precise extraction will make a cup of Folgers Country Roast taste downright palatable, and an uneven extraction will make even Counter Culture’s Gesha taste like a Chinese take-out box full of last night’s alley cat anus.
When brewing coffee there are two extremes, “over-extraction” and “under-extraction”, that you must ride the line between. By weight, 28% of a roasted coffee bean is water-soluble. If you extract too much of this your coffee will be over-extracted, if you take too little of it your cup will be under-extracted.
Lucky for us, both over and under-extracted coffees have distinct flavor indicators that will let us know where we went wrong and how to troubleshoot for our next brew. When you brew to over-extraction, you take all of the good stuff from the coffee that you want, but if the extraction doesn’t stop after the good stuff is gone, you will start to break down and dissolve the fibrous structure that supports the coffee bean. This fibrous structure is exactly what you *don’t want* in your cup because it will mask any nuance and sweetness present with a harsh, bitter, and hollow flavor. Conversely, if the brewing is stopped before we have gotten everything we want from the grinds, we will be left with an unbalanced, under-extracted cup that tastes characteristically sour, acidic, and lacking in sweetness. The ideal cup, one that is sweet, complex, and just downright pleasant to drink, is found in the balance between these two extremes.
How to Achieve Ideal Extraction…
An ideally extracted cup of coffee may seem like a daunting and insurmountable task. When it comes to brewing a delectable cup of of joe, there are a million and one more ways to get it wrong than to get it right. But when one breaks down the principles of brew science, there are a surprisingly small number of variables that can be controlled to dial into exactly what you want in a coffee…
With most brew-methods, grind size is the single largest factor you can influence to improve your brew. The finer you grind your coffee, the quicker it will be to release its water solubles, and the the faster it will extract. The converse is also true. The courser you grind your coffee, the more fibrous material there will be for the water to soak through, and the longer it will take to dissolve and release everything that you want from the coffee.
Conceptually, brew time is pretty straight forward. The longer that water is in contact with your grind, the longer that the grinds will extract. Increase brew time to increase extraction, decrease brew time to decrease extraction.
This variable is best controlled in “Immersion” style (French Press, Clever Dripper, Cold Brew) brews, but can also be tweaked in the length of your pour-over’s bloom.
Just like sugar and salt dissolve faster in hot water, the water-soluble flavor particulates in coffee will extract more quickly in hotter water. Ideal water temperature ranges from 180 F- 206 F, depending on your method of brewing.
I hope this cleared up any confusion you might have had in regards to making yourself a great cup of coffee. If you are still lost and don’t know where to start, check out our Brewmaster's Guides in the Blog Archives. We have done all of the legwork to bring you clear, step by step directions that will take you straight to your best brew to date.