Coffee Extraction Theory

At first glance, extraction may sound like some fancy piece of professional jargon that only baristas truly comprehend. FALSE. If coffee is your jam, whether you’re just getting started or you’ve been in the caffeination game for years, understanding the ins and outs of extraction is invaluable in achieving the ideal cup of coffee.

When we say extraction, we’re talking about the process of dissolving ground coffee in hot water. All that dissolved stuff creates the flavors that constitute the profile of your finished brew, and there are a whole bunch of contributing factors that can affect that profile. To learn how to harness the powers of extraction to produce a well-extracted cup, read on.

Extraction starts as soon as water makes that initial contact with the grounds. CO2 is released, which is a good thing; it produces an unpleasant sourness in your coffee (not to be confused with floral, fruity acidity). This degassing also pushes water away from the bean bits, temporarily disrupting extraction and ensuring you won’t get any inconsistent flavors.The oils and fats that make up the body of the coffee are the next compounds broken down, followed by the sugars, and finally the actual plant matter of your bean, which contributes a dry bitterness.

If you’re asking yourself why anyone would bother messing with any of this at all, beware over or under-extracted coffee. The over-extracted cup will be replete with an intense bitterness, accented by burnt notes, and a hollow body, On the other end of the spectrum, an under-extracted coffee will taste sour, overly acidic, and salty. Spending the time to learn the art of bean wrangling will guide you to that sweet spot--which varies from person to person--and you’ll be handsomely with a balanced, tasty cup of coffee.

extraction theory (over/under)
Illustrations by Courtney

 

Here’s where you can get in there and manipulate the flavor of your beverage to your liking. By understanding the brewing elements that affect extraction (incl. how to avoid over & under-extracting), you thereby become the master of the rate of extraction and garner yourself the golden opportunity to amp up or tone down certain aspects of your coffee. The factors that determine this magical rate (A.K.A brew time) include grind size, water temperature, agitation, and brew ratio. 

When contemplating grind size, one must consider surface area; more exposed area means more dissolved flavor stuff, and therefore a faster extraction. For example, for espresso, you’d want a finer grind, as the water passes through the grounds very quickly, while for cold brew, a coarser grind is ideal, as the grounds will be sitting in the water for an extended period of time. Let’s say your cup is tasting watery and overly acidic. You’re probably using too coarse a grind; those solids aren’t releasing enough flavor. On the other hand, an exceedingly bitter taste may indicate too fine a grind.

estaction theory grind

 

Water temperature directly impacts the rate of extraction; hotter water makes for faster extraction. The optimal range for brewing coffee is usually between 196℉ and 205℉; temperatures higher than than means a all that coffee stuff is getting dissolved too quickly, which leads to over-extraction (A.K.A untasty bitterness), and vice versa.

The ultimate goal is a nice, even extraction, so agitation between pours can help maintain a consistent extraction rate for all grounds. Water always takes the path of least resistance, which when it comes to brewing, means some grounds are left high and dry. Agitating or disturbing the bed of grounds ensures all the grounds get some love.

Brew ratio is pretty much exactly what it sounds like: the proportion of coffee to water. Most coffee preparations are made between 1:15 and 1:18 (A.K.A. the Golden Ratio), but a general rule of thumb to go by is 1 tablespoon of coffee for every 4oz of water. The idea is that you want enough water to allow all the grounds to have a chance to go through every stage of extraction, which is what will grant you that balanced cup you’re after.

extraction theory (factors)

 

The real name of the game here is experimentation. Play around with the aforementioned elements, increase or decrease your rate of extraction, and find what you like. As always, we’re here to answer any burning questions you may have, so feel free to give us a shout on instagram (@moderntimescoffee) or shoot us an email (coffee@moderntimesbeer.com).