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Coffee Data Science

Shifting Maillard Higher/Lower for Coffee Roasting: Feasibility

3 min readSep 2, 2025

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As I mess around with the Maillard reaction, I continue to do small feasibility studies to check for optimizations. Given my profile has become optimized in multiple ways, I wanted to check if shifting up or down the inlet temperature during the Maillard reaction would affect taste. So I made three roasts:

  1. Baseline
  2. +20 C higher during Maillard
  3. -20 C lowever during Maillard
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Post-Roast Metrics

All the roasts were dropped at 212 C bean temperature, and the resulting roasts had similar measurements.

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Press enter or click to view image in full size

This was especially true for coffee color.

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Press enter or click to view image in full size

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

I pulled four shot pairs, and the data showed Higher Maillard tasted better 3 out of 4 shots.

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Press enter or click to view image in full size

EY was not affected by these changes to the Maillard reaction.

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To expand testing, I’m going to look at a few more higher temperatures to see if there is something more optimal.

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

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Robert McKeon Aloe
Robert McKeon Aloe

Written by 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.