Coffee Data Science

The Revenge of Baked Coffee?

Baking coffee with a larger batch size

Robert McKeon Aloe
3 min readJun 25, 2024

My previous efforts to bake a coffee roast have failed to find a detectable difference in espresso taste. I wanted to try again, so I tried to flat line some coffee on the Roest. However, I still didn’t find a major difference in taste.

The roasts show temperature flattening out.

The RoR doesn’t go negative, and maybe that’s what I should insure in the next experiment.

Both roasts had similar crack patterns.

From the post-roast statistics perspective, both roasts were pretty close.

Tasting Equipment/Technique

Espresso Machine: Decent Espresso Machine, Thermal Pre-infusion

Coffee Grinder: Zerno

Coffee: Home Roasted Coffee, medium (First Crack + 1 Minute)

Pre-infusion: Long, ~25 seconds, 30 second ramp bloom, 0.5 ml/s flow during infusion

Filter Basket: 20 Wafo Spirit

Other Equipment: Acaia Pyxis Scale, DiFluid R2 TDS Meter

Metrics of Performance

I used two sets of 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).


I had four shot pairs, and there was not much difference.

All the shots has similar EY.

Unfortunately, I failed to bake a roast noticeable for espresso, but I should try again. It is possible that baked roasts are hard to distinguish in espresso compared to cupping or pourover.

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:

My Second Book: Advanced Espresso

My First Book: Engineering Better Espresso

My Links

Collection of Espresso Articles

A Collection of Work and School Stories



Robert McKeon Aloe

I’m in love with my Wife, my Kids, Espresso, Data Science, tomatoes, cooking, engineering, talking, family, Paris, and Italy, not necessarily in that order.