RATIO:
Ratio describes how much fresh ground coffee you’re using and how much water you’re applying to it. Common vernacular is a simple ratio like 1:17 (one part coffee to 17 parts water) for filter coffee, 1:2 for espresso, etc.
Ratio has a significant effect on your coffee but is easy to pin down ahead of time so that you can focus on other variables while brewing.
WATER:
Water is 98% of a cup of brewed coffee, so it’s important to take it seriously. Good quality water is a big step in quality coffee, so we recommend using filtered water. Common household water filters are a cheap and easy way to get quality brewing water in the home.
Also, important to consider is the temperature of your water. The Specialty Coffee Association recommends using water between 195 and 205 degrees Fahrenheit for making coffee. A great tool for this is an electric kettle with temperature control, but it’s not necessary to get you water to the right temperature range. Just boil your brewing water and remove it from heat. After 30 seconds, you water should be in the ideal temperature range!
TURBULENCE:
This term describes the way your water and your coffee grinds interact. A gentle, slow trickle of water provides low turbulence, while a vigorous pour provides high turbulence. Different brewing methods will require different levels of turbulence, including physically stirring your brew bed in some cases. As a general rule, it’s best to keep turbulence fairly low in order to stay repeatable from brew to brew, and also to void kicking up excessive fines, which can settle all together and create a clogging effect on water as it passes through your brew bed.
CONTACT TIME:
Making coffee involves a process called extraction: water makes contact with coffee and “extracts” material from the grinds. This process requires contact between water and coffee, but also requires time. The longer these two are in contact, the more extraction will take place – generally speaking. You can control contact time, to an extent, by pouring more slowly or more quickly. The level of turbulence you apply also can affect time as described above. However, the biggest effect on time, and on your coffee’s flavor overall, is the grind size.
GRIND:
The grind size is our last variable, but it has one of the biggest effects on your brew. As coffee is ground, more surface area is exposed for water to come in and extract from. This means that – generally speaking – a finer grind exposes more surface area and allows for more extraction. Conversely, coarse grinding reduces the surface area exposed and leads to less extraction.
Different brewing methods require different grind sizes – from fine for espresso to coarse for something like French press – depending on the specifics of the method itself. For this reason, grind size is one of the first and most important variables that should be decided on when brewing coffee. Set it and your ratio, then move on with the brew and evaluate afterward. There are a few ways you can determine if a grind change is needed:
By taste: if your coffee tastes overly bitter, intense, chalky, etc. then it is likely over-extracted, which can be corrected for by coarsening the grind. If your coffee tastes weak, sour, salty, and generally underwhelming, it is likely under-extracted. Setting the grind finer, in this case, will help extract more.
By time: if your coffee takes longer than expected to finish brewing, or perhaps the brew bed is “plugged up” and won’t let water through, then likely the grind is too fine. If the brew finishes far too quickly, the grind may be too coarse.