By Michael Haft and Harrison Suarez
With the principles of Golden Ratio in mind, pick a preparation method. These lie along a spectrum: Body on one end, flavor clarity on the other, with variations in between. The balance between body and flavor clarity is determined by the parts of the coffee bean that make it into your cup.
Unfortunately, way back at the beginning of our journey when this was all foreign to us, no one ever explained why a French press had so much body or why a pour over had such articulate flavors. It was all shrouded in secrecy. So we took these mysteries at face value and filed our questions away.
Eventually, we discovered that the answer lay in chemistry, which divides the world into soluble and insoluble compounds. Soluble particles are extracted from the coffee grounds and contribute to flavor and aroma, while insoluble particles primarily contribute to the body of coffee. Since a roasted coffee bean is made up of both types of particles, the way you balance those during the extraction process determines the resulting character of your cup.
Do you prefer a richer, grittier cup of coffee? Try a French press. Looking for a cleaner cup that can highlight citrus notes from South America or berry flavors from Africa? Check out the pour over. Everyone’s preferences vary, but once you select a method, you can further fine tune your coffee by adjusting these variables:
The grind size of your coffee beans: Grind size affects the extraction rate because it affects surface area. Beans that are coarsely ground have less surface area than the same amount of finely ground beans, making it more difficult for the water to penetrate and extract the coffee solids. A uniform grind size means that the extraction rate of the oils and acids in the coffee will be consistent. You won’t have large pieces that under-extract and small pieces that over-extract. It’s for this reason that you’ll often hear coffee experts exhorting people to invest in a good burr grinder. And guess what? They’re right.
The temperature of your water: Temperature affects extraction rate because solids dissolve more quickly at higher temperatures. Temperature also affects flavor because it determines which solids get dissolved. Using water that’s too hot will lead to sour coffee since it releases unpleasant acids from the coffee beans. For this reason, we recommend brewing with water between 195(F) and 202(F) degrees. And remember, measure the water actually in the coffee and not just what you’re pouring. There’s often a difference.
The amount you agitate your coffee grounds during brewing: You can further manipulate the brewing process by agitating the coffee grounds as the water passes through them. Agitation works because it accelerates the spread of dissolved coffee solids throughout the water, exposing the coffee grounds to fresher water more quickly. But agitation also has the effect of cooling the water, which we know can affect the process. In the end, it’s just one of those things that you learn through trial and error.
The ratio of water to coffee: Strange how it keeps coming back to this, right? The key difference here is that when you’re fine tuning, you aren’t sticking strictly to the Golden Ratio. Instead, you’re adjusting to taste. To make adjustments more easily, invest in a scale. You can be more precise by using weight—instead of volume—to measure your coffee and water.
One final point. As any good barista will tell you, make sure to adjust only one variable at a time so you can accurately track results. Changing two variables at a time confounds the outcome, and you won’t know whether it was because you changed variable X or variable Y.
For all our talk of chemistry, particles, molecules, and extraction percentages, brewing great coffee is much less about science and much more about art. Once you learn the principles that underly the brewing process, you can develop a routine which suits you perfectly.
And that’s the beauty of coffee. When we first started our journey, we were embarrassingly ignorant about the most basic aspects. The choices, the culture, the equipment—it was all so overwhelming that we had no clue where to begin.
But pretty quickly we found ourselves climbing the coffee learning curve. Learning to brew great coffee didn’t have to take forever. It was a hobby that you could pick up on a Saturday morning and feel good about.
This post is adapted from Michael Haft and Harrison Suarez’s Perfect Coffee at Home.
This article available online at:http://www.theatlantic.com/health/archive/2013/08/how-to-make-perfect-coffee/278944/