Coffee Data Science

Sweeping End Bean Temperature for Extended Development in Coffee Roasting

Slowing down the development phase

In tweaking the development phase of coffee roasting, I did not see a benefit to an extended development when dropping coffee at 212 C bean temperature. However, that means the end roast temperature might be better optimized. I explored sweeping the end temperature while extending development.

I made 4 roasts:

1. Baseline at 212 C end bean temperature
2. Extended Dev at 210 C end bean temperature
3. Extended Dev at 212 C end bean temperature
4. Extended Dev at 214 C end bean temperature

Post-Roast Metrics

The roasts ending at 212 C had some differences in metrics, but the Extended Dev 210 C was close in color to the baseline.

The density was lower for all of the extended roasts, which is curious.

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

The Extended Dev 212 C almost matched the baseline, but the 210 C tasted better. The 214 C predictably performed worse.

There was no major difference in EY.

This suggests I should explore extending development while lowering end bean temperature.

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My First Book: Engineering Better Espresso

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