Coffee Data Science
Fast vs Slow RoR in Coffee Roasting
Rate of Rise Explored!
I have been curious how to modify the Rate of Rise (RoR) during coffee roasting to better understand how that impacts taste during the Maillard phase. Generally, the thinking behind RoR is that it should be gradual, not have spikes, and not go below zero.
For this test, I used a BT/IT profile (bean temperature drives what the inlet temperature is going to be). I then made a fast and slow RoR profile.
The RoR had the desired impact, but it also did not have a massive drop probably because the curves converge around the time of the first crack.
Post-Roast Metrics
The roasts were ended at a bean temperature of 212 C. Output weight drop and density were about the same for all three.
Even coffee color was very close, which is what I aim for.
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).
Shot Data
I pulled four shot pairs, and this should just be a feasibility to see if there is some major effect. From this data, the baseline is better than both variants.
EY was nearly the same across all three.
I looked at modifying the Rate of Rise, and I didn’t find an improvement in either going much slower or much faster. There is probably more nuance to be discovered related to the effects on the dry and Maillard phases.
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Further readings of mine:
My Second Book: Advanced Espresso
My First Book: Engineering Better Espresso
