Coffee Data Science
The Maillard Reaction is not a Duck: Coffee
Maillard encore
The Maillard reaction is so important in coffee roasting, so I have continued to explore how changing the roast parameters affects that process. I looked at slowing the fan down during the Maillard process, but I brought the fan speed back to normal at the end of the Maillard. What if I keep the fan slow until the end? I also used the fan at 100% for the roast as a counter example in the experiment.
Post Roast Metrics
These roasts looked very close to one another.
Moisture was also similar.
Water activity is reported, but I’m still unsure if water activity in roasted coffee is a good metric.
All the roasts had a similar density.
The color of the roasts were close, within 3 points of the average, so hopefully any taste differences are only from how the beans were roasted.
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).
Shots
The results were from four shot pairs, so clearly these results are to gain intuition more than anything. The slow fan during Maillard showed an improvement in taste similar to my previous experiment. However, slow to the end didn’t change performance much.
Even the fan high did better than the baseline, so this could be a bit of noise. There is also a possibility the beans chosen roast differently than others. Bean selection for feasibility experiments is difficult as a single test might show a roast improvement is not ubiquitous.
Extraction yield was roughly even across roasts, so I don’t think their taste differences were caused by an extraction difference.
This test didn’t show an improvement by extending a slow fan speed past the Maillard reaction temperatures. However, it did get me thinking about how to test better across more bean types. Other experiments will explore the caramelization phase, which occurs after the Maillard reaction.
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Further readings of mine:
My Second Book: Advanced Espresso
My First Book: Engineering Better Espresso
