Coffee Roasting Advanced Course with Café Sublime

Avoid the Roaster's Mark to Bring Out the Best

Café Sublime’s Coffee Roasting Basics course opened my eyes and inspired me to learn even more with this Advanced course. The icing on the cake was that this turned out to be a one-on-one course where I was the only student, compared to the group setting of the basics course.

While the basics course was much more focused on history, theory and application at a small scale, the advanced coffee roasting course started each day with some additional bits of scientific theory and a whole ton of practice. Once again taught by roast master Jorge Sotomayor ( jorgesot) and barista Fabrizio Seed ( fabrizioseed), the advanced coffee roasting course solidified everything I learned across both courses to a point where I truly have the confidence to go out and roast coffee.

Jorge, as head roaster of Café Sublime, has set the goal and challenge to avoid leaving the “roaster’s mark” on the coffee beans and instead roast in a way that allows the natural characteristics of each varietal to flourish. I wholeheartedly subscribe to this philosophy and mission statement. If I ever open my own coffee roastery, I will unshakeably apply it there as well.

Coffee sensorial evaluation chart Cropster

There really is no such thing as a roaster “extracting notes of X or Y through my roast.” In reality, the best a coffee roaster can strive for is to highlight the characteristics that the coffee bean already naturally contains as a result of its unique varietal, environment, growth, and fermentation.

Analyzing roasting curves was a major part of this advanced course that while not strictly required to understand coffee roasting or do it well, provides a level of data second-to-second that exponentially improves the ability to interpret and adjust roasting variables (like temperature, pressure, level of flame and hertz) on the fly to much more specifically hone in on a desired outcome.

I won’t bombard you with all the minute details of the science of coffee roasting, which you should really learn for yourself through one of Café Sublime’s courses (if you speak Spanish), but here are some highlights of what I learned about in the 3 day Advanced Coffee Roasting course.

Practice, Practice, Practice

1. Water Activity vs Humidity

While we learned about thermodynamics and physics as they related to coffee roasting during the basics course, the advanced course shifted gears to talk about the difference between the humidity and the water activity of a bean. While humidity has been a frequently discussed variable in coffee roasting, water activity is a much newer detail that very few are incorporating into their process. Humidity is essentially the quantity of water in the bean, while the water activity is how much of the bean is available and free to use.

2. Small Batch Coffee Roasting to Test Theories

We roasted 16 batches of 150g to evaluate, calibrate and reach a common ground before moving on to larger batches. For each varietal, we roasted one batch under the exact same settings and conditions to operate as a control, and the second batch to test our theories and approaches to attempt to bring out the best in the bean after also analyzing each control batch’s curve to see how they turned out. 

3. Soluble vs Volatile

Understanding the differences between solubles (soluble in water) and volatiles (soluble in air) helps to ensure the quality of the final product of the coffee process: the drink itself. The volatile aspect of coffee beans highlights why freshly ground beans make all the difference. The second beans are ground, they immediately start releasing the aroma into the air, never to be recovered again. So always grind your coffee and then brew it right away!

Giesen coffee roaster at Café Sublime
coffee cupping and evaluation practice

4. Coffee Cupping, Evaluation & Calibration

When roasting 16 batches of coffee, naturally you must also cup and evaluate 16 batches of coffee. First came a calibration to see where everyone sat on the scale. Then, after spending the better part of the afternoon cupping, we had a lengthy discussion about our evaluations and desired roast profiles compared to how the batches turned out. In addition the roast curve analysis, I had some homework to determine which two varietals I wanted to apply my small batch learnings into bulk roasting and how I would adjust to more closely arrive at my desired result.

5. Coffee Roasting in Bulk

Applying small roaster adjustments to a massive roaster has its nuances. Of course with the much larger amount of space within the drum, the scientific aspects required some adjustments to reach a baseline but once I was clued into those, it was off to the races. Moving on from the small 150g batches to 7kg batches was certainly daunting but the same theory applies and the actual methodology is the same with just some tweaks in the aforementioned variables. I roasted 2 and Café Sublime’s two primary roasters each did one batch as well. Let’s just say, for a process that lasts on average between 6 and 10 minutes, it is still surprising (and exciting) to know that the first minute and a half of the process, and also a span of 6-8 seconds after about a minute on from first crack can make or break your batch.

6. Practice Makes Perfect

It is best to let a batch sit and rest for at least two days before cupping, but we decided to dive right in after about 45 minutes and cup the four 7kg batches to see how it turned out. Of my two batches, the first one I clearly butchered. Due to the quality of the bean, it still survived and had some interesting characteristics but due to my overapplication of heat ended up being much more on the caramelization end of the spectrum. My second batch I am happy to say was delicious (in my own personal opinion) and had intense notes of mango that I loved. While from an objective evaluation POV, I could have made some adjustments and given it some more time to even it out, I am quite satisfied with how it turned out. Now that I have a great base and starting point, all that’s left is thousands of batches worth of practice. I can’t wait!

Learn more about coffee in GDL with the Guadalajara episode and while you’re at it, read more about traveling to Guadalajara.

For more about Café Sublime’s coffee courses, check out my articles on the Coffee Roasting Basics course and Espresso Fundamentals course.

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