Coffee Data Science
Steam Pre-Infusion for Espresso: A Summary
Collecting some steam
Steam Pre-infusion started because of my experiments comparing the Decent Espresso (DE) Machine and the Kim Express. Then I worked to identify some of the reasons the Kim Express outperformed the DE, and I discovered some steam pre-infusion. Then I worked to understand it, and eventually I designed a profile for my DE to try to emulate it.
Here is the outline of this summary:
- Comparison of the DE to the Kim Express
- The Coffee Sneeze
- The History of Steam Pre-infusion
- Steam Pre-infusion for the DE
DE vs Kim Express
I felt after five months of using the DE that I should do a paired test against my Kim Express.
The Kim wasn’t just a little better; the gap was huge. I’m still using my DE on a daily basis, and I believe it could do better. I don’t know how yet.
It caused me to think I missed a variable which is why this is called round 1. I believe I can make a better profile, but a deeper understanding of the Kim is necessary.
Coffee Sneeze
Over the past few months, I’ve observed a small coffee flurry before each espresso shot.
I didn’t know what it was, but after viewing some videos, I found the initial pressure change caused a small amount of fines to blow through the puck and out.
I call it the coffee sneeze.
After my comparison with the DE and the Kim, I looked at the sneeze again. In my quest for a better understanding of my lever and great espresso, I took an even deeper look at the coffee sneeze.
Steam Pre-Infusion
Steam Pre-infusion is not a new feature for espresso machines. There is an interesting history of machines that had some amount of steam pre-infusion without it being part of the design.
I took some slow motion videos of the Kim Express and the Decent Espresso machine without a portafilter. The aim was to look at steam pre-infusion. I slowed them down even more to understand how steam comes out first before water.
The real gem in these videos is the audio.
Emulating Steam Pre-Infusion
I spent some time trying to understand steam pre-infusion, and I figured out how to get a similar effect on the Decent Espresso machine using a very low flow rate at a high water temperature.
I’m not done in trying to optimize this first step, but I wanted to share what I have to help out anyone who wanted to try it out.
I hope these tests encourage a better understand of espresso machines and impact future design.
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