Modulating The Flavor Profile of Coffee by Rob Hoos

When I started roasting coffee in 2012, there were very few resources available from which to learn. There were (and still are) several forums one could follow and participate in to learn but that information isn’t well-organized or made to easily consume like a book.

Rob Hoos helped change that in 2015 when he published his manifesto titled Modulating The Flavor Profile of Coffee. One of the key things I love about Rob’s book is his focus on the science of coffee roasting, especially his focus on the Maillard reaction. His book has inspired me to further explore the reactions (actually the set of reactions), which has led to a better understanding of driving factors of a roast’s flavor.

See also: The Maillard Reaction: A Practical Guide

Modulating is organized into the following sections:

• Opening
• A Manifesto
• A Change in Paradigm
• The Importance of Sourcing Appropriate Green Coffee
• Charging Toward the Beginning of Chemical Reaction
• Maillard Reaction
• Development Time
• Degree of Caremilization/Pyrolysis
• Building Up Pressure In The Coffee Seed During Roasting
• A Summary of Flavor Modification
• An Ending of Sorts
• Appendix A: Thinking About Flavor

The book walks through the commonly accepted stages of a roast and provides a technical explanation of some of what’s going on physico-chemically at the time and ways to influence that.

I’ve had the pleasure of taking a class taught by Rob in Singapore and in that class Rob spoke about what he called the “old paradigm” of coffee roasting, which emphasized the art and craft of roasting. This was roasting primarily by the senses; sight and smell, using color changes such as “yellowing” and smells such as “hay” as signals to the operator of changes occuring in the bean. The new paradigm according to Rob is to “know how and why” and to “take control.” He advocates a more data-driven style of roasting—in addition to using one’s senses—focusing on five control points in the roast:

1. Drying Phase
2. Maillard Reaction Phase
3. Development Phase
4. Extent of sugar caramelization
5. Total time

Modulating gives an operator a better understanding of those five control points, ways to control the roasting environment around those points, as well as references for readers who want to explore the topics further.

Update March, 2019: Modulating has been such a valuable resource for me personally as a roaster, that I use it as a reference for my training materials!