Science of Coffee: Tasting Extraction
November 3, 2019
Hi I’m Renee, welcome to our new series “The Science of Coffee.” Coffee brewing is one big chemistry experiment all backed by extraction. Extraction is the process that pulls out all of the flavors from the coffee into the water, making a really great cup of coffee. This is dependent on quite a few things, water temperature, the time, the grind and the ratio of the ground coffee to the water. So today my experiment is going to be all about extraction as it pertains to grind. So I’m going to brew three Chemexes today, one with each grind. And each of these will cause the water to go through the path of the grinds at different rates, effecting the rate of extraction of the coffee. Alright let’s get set up. So I’m going to grab my scales and my Chemexes. We’re going to start here with the fine grind, this will be the middle of the road perfect for a Chemex, and this will be the grind that’s really coarse. So as I bloom the Chemex and get ready for the actual brewing, let’s talk solubility rate. Coffee is about 30 percent soluble in water, meaning about 30 percent of the coffee will actually dissolve in the water. But the target is about 18 to 22 percent.
Alright we’re going to start with the Chemex where the grinds are really coarse. There are multiple flavor compounds that are in coffee. Mainly these are acids. And so when you have coffee that’s under-extracted, meaning that there’s not a lot of time that the water takes to get through, you’re gonna really only pull out those acids. And we can kind of see here how the water is really just rushing through those grinds. The result is going to be something that’s super sour maybe even grassy. Where as if you were moving to the Chemex that has the grinds that are ground appropriately for this. You’re going to have a good intermingling from that water and that coffee. This will result in a more balanced cup of coffee. Then as I move on to the third one, this water is picking up the acids and the sugars, but it’s also degrading some of those compounds. So this one is going to result in a flavor that’s super bitter or really sharp tasting. And then when they’re finished brewing we’ll do the last part of the experiment, the favorite part, the taste test. So the one with the grind that was super coarse is actually really light in color, so let’s give it a taste. Ooh, real sour, not my favorite. Moving on to the one with the appropriate grind. Oh yeah, that’s a lot better. It kind of has a little bit of sweetness on the tip of the tongue, I get some really good acids but it’s super balanced. And then this one. The last one was the one with the grind that was super fine and it even looks a little bit sludgy. Well, let’s see what its like. That one’s really bitter, really sharp, and just kinda of an assault on your senses. It’s really, really, really strong. I realize the one in the middle that I liked probably is within this 18 to 22 percent extraction rate window, because it was super well-balanced and sweet. So the one thing I’m taking away from this is the easiest was to ensure that I can brew a really good cup of coffee at home is to control the grind. Make sure that I have the right grind for the right brewing method and it equals a delicious cup of coffee. Cheers.