Coffee Data Science
Super Baked Coffee for Espresso
Third time is the charm!
I have tried a few times to better understand baking a roast. However, I found in two prior experiments that the baked coffee didn’t taste different than the baseline, so I thought I must be doing something wrong. It is important for me to be able to understand how a baked roast tastes in the extreme case so I can better understand how to taste bakedness in the mild case.
After encouragement from Valerian at Boot Camp Coffee, I baked again. I baked for 5 minutes and then for 10 minutes. I wanted to go to the extremes of baking.
Roest Roasts
I roasted three 120g batches on the Roest, so I could pull 4 shots per sample. The roasts followed the same profile, and at the end, I manually dropped the temperature to get to a negative or zero Rate of Rise (RoR).
I got the RoR negative and then just flatlined it.
Post-Roast Metrics
These roasts are a little challenging to compare for fairness. I would prefer the post-roast metrics to be closer especially weight loss and color. Weight loss was quite higher for the two baked samples.
Oddly enough, moisture was similar.
Water activity was less for the longer baked, but I’m not sure how important that is.
The baked coffees were denser which is not normally what one would expect from a roast with more weight loss.
In terms of color, the baked coffee is a full 10 points lower. This is much lower than I wanted, but we will work with these for this experiment.
Tasting Equipment/Technique
Espresso Machine: Decent Espresso Machine, Thermal Pre-infusion
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).
The Shots
These shots were very illuminating as I could definitely tell the taste difference of baked coffees. In the 5 minute baked coffee, the flavor seemed flat or muted, and it was not exciting. The 10 minute baked was a trainwreck. I couldn’t finish the shot without milk, and even in milk, it didn’t taste particularly good. So I only graded one espresso shot as a result.
For extraction yield, they all had similar performance which is a good sanity check for taste.
I went to the extreme to find baked coffee, and I have found a lack of all that is good in flavors. This is exciting as it helps me orient myself in the space of tasting dullness with greater confidence.
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
