Filter coffee, Extraction, and Pour-over Break Down
Let’s set the record straight about filter coffee. What is it? Filter coffee can most easily be defined as all brewed coffee except espresso. The main differences between espresso and filter methods are the amounts of pressure used for extraction and the coffee’s grind size. Unlike espresso, filter coffee uses gravity to push water through the ground bed. Because of this, the flow-rate of water through the ground bed is completely determined by the size of the coffee grounds. A bigger grind size allows water to pass through the coffee grounds faster and a smaller grind size slows the flow rate down. The time water spends with the coffee you’re brewing determines how much extraction you achieve. What is extraction…? Good question. Keep reading.
Essentially, extraction is a more scientific term for brewing coffee. Extraction refers to the combined concepts of thermodynamics, dilution, and dissolving soluble elements out of roasted coffee. These principles are complex and, in their depths, require a lot of chemistry and physics to truly understand. But, don’t be intimidated! You can still understand and make great coffee even if you didn’t do so great in your high school chemistry class. Let us simplify it for you. Coffee extraction occurs by using heat energy to dissolve soluble compounds into the water. This hot collects coffee soluble compounds that make up your cup of coffee. In coffee brewing (in filter coffee especially) we are looking for the perfect balance of these compounds.
Brewing coffee to its highest potential requires a ratio. Too much water can lead to an over-extraction resulting in a bitter cup. Too little water can result in an under-extraction which results in a sour and more vegetal flavor. The most commonly used filter coffee ratios fall between a 1:15 to 1:19 meaning one part coffee to fifteen parts water (i.e. a 1:16 ration using 25g of coffee would require 400g water [25x15=400]). Once your desired ratio has been determined, you must determine a grind size that accompanies your ratio. The best way to do this without making it too complicated is by trial and error. Learn to trust your pallet and find an extraction ratio that works for your taste. The coffee industry refers to aligning all these factors as “dialing in” a coffee.
Chemex: Mostly known for its iconic shape, this hourglass-shaped glass brewer utilizes thick-bonded filter paper that results in a very tea-like cup of coffee. We think it expresses the flavors of lighter-roasted, fruit-forward coffees the best.
V60: Like the Chemex, the V60 is conical brewer than comes in a glass, ceramic, and metal version. Its interior contains spiraled ridges that maximize the ground bed’s ability to expand in the brewer.
Kalita Wave: This brewer has a flat bottom unlike the v60 and Chemex which allows for a more even extraction by making the ground bed flat the flow rate more predictable. It also utilizes a filter with waved sides that act like the ridges on the V60.
Other Types of Filter Coffee
Automatic Coffee Maker: More commonly referred to as a “coffee pot” this filter brew method was the American standard before coffee-pod machines made it to the scene. They are making a comeback with companies like Moccamaster who make a very precise automatic brewer.
French Press: Another classic, the French press utilizes immersion extraction brewing. Once the coffee has reached the desired strength, you plunge the press and a wire mesh filter separates the coffee from the grounds. This produces a very heavy cup.
Aeropress: Shaped like a giant syringe, the Aeropress is another immersion brewer. Coffee and hot water are added to the center chamber and after the desired brew time has elapsed, the plunger is pushed and the coffee is separated by a filter at the bottom of the chamber.
Whether you're having a poor over in a coffee shop or starting your own hand-pour journey at home, the best way to become a master at making great filter coffee by doing it. Cheers!