In this portion of the guide we will describe the purpose of the coffee brewing control part and leave you with an understanding of how it can be used to tweak your coffee brewing ratio and tailor your coffee to just the right flavor and strength you want it to have.
A coffee brewing control chart is critical to achieving a desired result in brewing coffee.
Used with a refractometer the control chart is designed to help you adjust the dosage and methods according to the requirements you specify.
An important exception to keep in mind when reviewing the chart is that it does not apply to espresso - as espresso is a deliberately concentrated drink and has a larger volume of coffee solubles.
Also worth mentioning is the fact that the Specialty Coffee Association of America (SCAA) and The Speciality Coffee Association of Europe (SCAE) have determined different “ideal” strengths for the coffee brew.
How to Use the Coffee Brewing Control Chart
To apply the chart you can take a given amount of coffee, like 50 grams of coffee for every 1 liter of water.
Then take the following steps:
Brew a cup of coffee with whatever method you prefer and the ratio of coffee to water you chose.
Apply a refractometer or brew strength meter to measure the concentration of coffee solubles in the cup.
Refer to the chart, and then follow the diagonal line down from the quantity of coffee you chose (let’s say 50 grams) until you get to the percentage of coffee solubles you measured out with the refractometer.
Once you’ve found that point - follow the line down vertically and it will tell you the extraction.
So, for example, if you were using 50 grams of coffee per liter of coffee and the refractometer determined your concentration was 1.45% then this chart would tell you that the extraction level is 26%.
In this case the chart would help us determine that coffee falls squarely into the category of “strong-bitter”.
Lowering the soluble concentration to roughly 1.20% would bring the coffee very close to ideal.
This could be achieved by increasing the level of grind or decreasing the brew time (or some combination of the two).
Did You Know?
Ernest Earl Lockhart, a chemist from Boston, designed the first Coffee Control Chart in his 1957 paper titled “The Soluble Solids in Beverage Coffee as an Index to Cup Quality.” He went on to become the first director of the Coffee Brewing Institute (CBI).
What do the diagonal lines on the coffee brewing control chart represent?
Those lines represent the brew ratio (concentration / yield) needed to achieve the balance you are looking for (Weak, Ideal, Bitter) etc..
How do you calculate TDS for coffee?
The most precise and accurate way to measure the TDS for coffee is to use a refractometer.