Coffee Data Science
Control Chart Misconceptions in Espresso
Let’s get something right
A control chart is used in espresso to give an aim for people when they’re pulling shots so they can see where they should go in their extraction. The ideal extraction yield should be 18% to 22% of the input coffee, and for espresso, the ideal concentration in the drink has been said to be between 8% and 12% of the shot.
I think this is wrong, and I’m not the first to say this. There have been some longer shots pushing 26 or 27% extraction in a slower, longer ratio shot.
I’m sure those beverages are good, but I think we should be pushing into the zone on this chart labeled as Over-Extracted (Strong and Bitter). I actually doubt many people have had shots in this range.
To get to this range is difficult for a light or medium roast. I’m sure people can get into this zone with darker roasts, and I’m sure they don’t taste so great. I have had that experience. However, with light and medium roasts, I have had my best shots in the top right corner of the chart.
My shots have regularly been between 20% TDS at 22% to 25% EY, which is a very short shot. I’m sure you could add water to make it not as strong, but these shots do not have the gross flavors typically associated with higher EY brews.
With all the new gear, tech, and data, we should re-examine if this chart holds true.
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Further readings of mine:
My Second Book: Advanced Espresso
My First Book: Engineering Better Espresso
