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Extraction in coffee brewing
What is extraction?
Something that is not often talked about in coffee brewing techniques is extraction. Extraction is the action of taking something out and in our case we are taking out the flavours from the coffee grounds. If you can better understand the extraction process in coffee, you’ll be able to consistently brew a great coffee everyday. As you know, coffee is just a combination of coffee beans and water, so how can we bring the most out of our coffee?
What makes a good extraction?
I think a well brewed coffee is a coffee that is evenly extracted. An evenly extracted coffee would mean all the coffee grounds have been exposed to water for the same amount of time. It sounds very simple but there are several variables that affect this greatly: grind size, timing and temperature.
In regards to grind size, it must be evenly ground for an even extraction. Generally speaking the finer the grind, the more even it is. If you’re unsure about whether or not your grounded beans are even, there are devices that can sift your beans such as the Kruve sifter. There are also certain devices with longer drip time, so it may be better to go with a coarser grind.
I’ve done a lot of testing around timing my brewing and I’ve noticed that the coffee is going to be extracted within a two minute window. To test my hypothesis, I used a brewing stand and switched to a new cup every few seconds. I was able to taste each part of the coffee being brewed out. My discovery is that most of the flavours are extracted within the first 45 seconds and after the two minute mark there was an extreme lack in flavour. From my understanding, this is because caffeine is a soluble compound and that’s why most of the flavours come out during this time while the caffeine is being extracted. The rest of the brewing process is to balance out the coffee. For example, espresso is extremely tasty, yet it is extracted in a very short amount of time. You could argue that the espresso is pulled with pressure, but it also has to do with timing. Baristas make up for the strength or texture of the coffee with speed and a metal filter.
The last major factor is water temperature. What is the ideal water temperature and how does it affect extraction? The higher the water temperature the more gases are going to be released initially (first 45 seconds) so the higher the temperature the faster the extraction. However, it becomes harder to control the extraction, since more gases are being released early on, this will prevent the water from being in contact with the beans. If you pour too quickly the water will be forced away without extracting any flavours. In conclusion, my suggested water temperature is under 94 degrees Celsius.
Things to look for when extracting coffee
A well extracted coffee starts from the beginning. When brewing with percolating methods, it’s important the first few drops come out strong. Often people pour too quickly and start with an under extracted coffee so the coffee comes out too thin. In regards to agitation, I am a huge fan of agitating my coffees at the end of the brew. No matter what brew method I use, I will give the coffee a quick stir as it is finishing. The quick whirl gives a last second push to extract everything from the brew.
Hope this helps everyone with their brewing. The basics of brewing a good coffee starts from understanding how the flavours are extracted. We will be writing more blog posts on brewing techniques in the future so stay tuned!