Coffee Data Science
Caffeine in Espresso vs Pourover
A second look
James Hoffmann did a video at the beginning of 2023 about caffeine. I pulled the presented graphs back then, but I didn’t notice anything particularly interesting so I didn’t write about it. More recently, I have become slightly worried I’m drinking too much coffee, so I relooked at the data.
James looked at caffeine and extraction yield for both espresso and pourover using salami output, so each brew had a few data points. I think the data points towards the efficiency of caffeine extraction and brew methods, particularly that extraction yield might not be a great indicator of caffeine extraction efficiency.
Total Dissolved Solids (TDS) is measured using a refractometer, and this number combined with the output weight of the shot and the input weight of the coffee is used to determine the percentage of coffee extracted into the cup, called Extraction Yield (EY). Typically, one aims for 18% to 22% extraction or some times higher, but it is difficult to get more than 30% EY.
Data
Looking at espresso and pourover separately seemed to meet expectations, but there wasn’t a great comparison on one graph with them together. So I did that for extraction yield.
Espresso is able to achieve a higher total EY in a shorter ratio, but what about caffeine?
Caffeine in pourover is much higher. The input dose for both brews was the same while the water contact time and temperature was different.
If we compare caffeine to EY, there is a trend, but the slope for pourover is steeper.
If we look at the maximum achievable caffeine extraction and extraction yield, pourover is closer to y=x, which means that the caffeine extraction is tied to the solubles extraction. Espresso is less efficient but does catch up closer to the end.
Assuming the max EY is 30% and the max caffeine is roughly 1.5% of the coffee grounds (18g input, so 270mg of caffeine), we can look again and see this trend of espresso being inefficient for caffeine.
For James’ steep experiments, he didn’t share any data or graphs to back his conclusion that caffeine saturated in extraction around 2 minutes. It would be interesting to see that data as well.
This is a small sample of data, but it makes me wonder about caffeine extraction efficiency especially across roast level and brew type. I think this could be informative, and maybe I’m not drinking too many espresso shots a day.
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Further readings of mine:
My Second Book: Advanced Espresso
My First Book: Engineering Better Espresso
