Feb 22
COFFEE DATA SCIENCE
Staccato Espresso on a Super-automatic Machine
Utilizing the coffee ground bypass
My in-laws got a new super-automatic this year, and it is the first time I was able to use a bypass feature in one. I have had a superautomatic for 10 years, and I think they are useful when things are busy. This one is a Phillips, and they make a super-automatic for just about any price point.
This one makes other non-espresso drinks, and it has adjustments for dose, output, and temperature. So I wanted to see if I could make a staccato espresso shot on one of these machines. I found I was not able to optimize the machine parameters sufficiently to make a good staccato shot, and I didn’t have the time to get a better staccato shot dialed-in. However, it was an enjoyable experiment, and most importantly, I didn’t break their new machine.
I used the Rok grinder, and I looked at modifying dose level a bit. I think if I had one of these super-automatic machines at home, I would be able to better nail down the input dose.
One of the major challenges is that the portafilter is pressurized, and I don’t have a lot of experience with a pressurize portafilter especially for staccato. The machine would usually choke at the beginning but eventually, it would get going.
I had to make the staccato shot backwards because the filter basket is actually upside-down. I’m sure that can cause issues in not being to pre-infuse the same was as a traditional machine, but maybe CO2 can be pushed out. I used two layers using the Fellow Shimmy, so it was split between at 300um (the product sheet says 200um, but the effective hole size is 300um).
The shot itself was already light colored, and this was probably due to the lack of pre-infusion. I suspect because the flow would be blocked, the pressure went up even higher.
One of the staccato shots had some major slow spots as indicated by the dark spots, particularly in the center.
In the cup, it looked a little light.
Metrics of Performance
I use two metrics for evaluating the differences between techniques: Final Score and Coffee Extraction.
Final score is the average of a scorecard of 7 metrics (Sharp, Rich, Syrup, Sweet, Sour, Bitter, and Aftertaste). These scores were subjective, of course, but they were calibrated to my tastes and helped me improve my shots. There is some variation in the scores. My aim was to be consistent for each metric, but some times the granularity was difficult.
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).
Intensity Radius (IR) is defined as the radius from the origin on a control chart for TDS vs EY, so IR = sqrt( TDS² + EY²). This metric helps normalize shot performance across output yield or brew ratio.
Performance
I have performance compared to a regular and staccato shot on a lever machine. In this setup, staccato didn’t taste better than regular shots which is due to the channeling occurring. I don’t think the shot was quite optimized for the machine.
In terms of EY, TDS, and Intensity Radius, regular shots were better. They were close to lever machine shots in EY but not TDS.
These experiments showed me that making staccato on a super-automatic needs some tricks to handle the difference in machine function. It is not as forgiving as a lever machine can be in terms of pressure profile and pre-infusion.
If you like, follow me on Twitter, YouTube, and Instagram where I post videos of espresso shots on different machines and espresso related stuff. You can also find me on LinkedIn. You can also follow me on Medium and Subscribe.
Further readings of mine:
Collection of Espresso Articles
A Collection of Work and School Stories
A Summary of the Staccato Lifestyle
Measuring Coffee Grind Distribution
Espresso Baskets and Related Topics
