The SCA identifies seven essential elements of coffee extraction, and in my experience, one of the most fundamental elements is the most ignored. In fact, it’s actually the first decision people typically make when they brew coffee, whether or not they realize it. That variable, of course, is coffee-to-water ratio.
Whether you’re a barista or a home brewer, when you reach for a Hario V60 or French press, you likely have an idea of how much coffee you want to make. Hopefully you’re using a scale to measure the exact amount of coffee you’re going to use. The recipe you use, whether carefully measured or inconsistently eye-balled, is your coffee-to-water ratio.
One of the main reasons your coffee-to-water ratio is important is that it largely determines what flavor combinations are possible. To understand why, take a look the SCA’s Brewing Control Chart.
The X axis represents solubles yield, or extraction. Essentially, it’s the percentage of the coffee mass that is dissolved during brewing and finds its way into the final brew. The Y axis represents solubles concentration, or strength. In other words, how much of your cup of coffee is actually coffee?
Most coffee professionals have agreed that filter coffee tastes best between 18-22% solubles yield at a 1.15-1.45% concentration. This range of possible strengths and extractions, often called “Gold Cup Standard,” are represented by the box in the middle of the chart. (it’s worth noting some industry leaders have recently argued for extractions greater than 22%. )
The diagonal lines represent different brewing ratios. They reveal different extraction/strength combinations are only possible with certain recipes. For example, a 19% extraction with a 1.41 brew strength is only possible with a 1:15 coffee-to-water ratio. (These numbers are based on average liquid retention rates). A close look reveals that a 1:17 ratio offers a greater probability of being “in the box” than any other ratio.
In my experience, few specialty coffee drinkers have embraced a 1:17 ratio. Many prefer the heavier body and more intense flavors of tighter ratios. But as the chart reveals, lower ratios are less likely to produce a full extraction. You’re leaving some of the best flavor in the brew bed, to be thrown away with the used grounds and filter.
An added benefit of using a higher ratio: you’ll use less ground coffee to make the same amount of brewed coffee. (Or, more likely in our case, use the same amount of ground coffee to brew a larger beverage!) Even switching from a 1:16 ratio to a 1:17 ratio over the course of a year will net you an entire 12 oz. bag of coffee!
Skeptical? Brew two different ratios side-by-side, test them blind, and let us know the results in the comments.