Author’s Note: I am indebted to Scott Rao and his incredible book “Coffee Roaster’s Companion” as well as Rob Hoos and his book “Modulating the Flavor Profile of Coffee” for lighting this fire in my mind. The ideas are my own based on my experience. However, I never would have thought to create this framework without their inspiration. Many thanks!
As the available information on roasting grows at a dizzying pace, it can often feel like you’re drowning in recommendations. In addition to personal preferences, there are seemingly conflicting theories from equally qualified individuals – some of which defy the laws of thermodynamics. It really shouldn’t be this complicated to learn how to roast and develop your personal style, but unfortunately it still is and we feel your pain! We’ve been there; sifting through the dogma and development time ratios to try and patch together a cohesive roasting philosophy. Oh yeah, and it has to taste good. Can’t forget that.
We’ve spent the last decade reading every book we’ve heard of, watching most of the videos on YouTube (not all, let’s be real), and attending workshops all over the world. We’ve learned a thing or two and we’d love to pass along the 7 Steps to Optimize Your Roasts that seem to be:
Widely Agreed Upon
We’re not saying everyone will agree with these suggestions. However, while folks argue over the finer points of expanding and contracting the Maillard Reaction, lovely people like yourself are missing some of the foundational aspects that are pretty well agreed upon.
Based in Science
This one has to make it in; Michael did study Mechanical Engineering after all. That means a lot of thermodynamics and heat transfer classes. Since a lot of information out there requires a B.S. in engineering to call BS, we’ve taken it about ourselves to do just that.
Proven Cup Quality
Many of the changes suggested have no basis in flavor impact. They’re more statements of logic i.e. “this should make it taste better” etc. We think cup quality is the most important thing, because, after all, coffee is for drinking. The question is, how to assess this?
Triangulation
This warrants a separate post but, in a nutshell, the only viable method for proven increase in cup quality is triangulation. That means there are three cups and one of them is different (a la Sesame Street, “which one of these is not like the other…”). If and only if the odd cup out is correctly identified AND what is different about it is correctly identified are the results considered valid.
So! Let’s dive in!
Over the last decade in coffee, we have seen most coffee roasters fall into one of two main categories. These are oversimplifications, so please don’t be offended. All maps are simplifications of reality, that’s why they’re useful.
The Two Camps
Folks in the first camp are those who treat all coffees as essentially the same; they may vary the drop temperature for a light, medium, or dark roast but that’s about all.
The second are those who treat every coffee as completely unique, adjusting every available variable for each coffee with no discernable pattern.
As is so often the case, we believe that the most effective path lies somewhere in between these two opposing extremes.
From a botanical, structural, and chemical standpoint, every coffee is over 80% identical. Approaching every coffee in a completely different manner denies this reality and sets us up for a lot of stress and hinders our ability to produce replicable results. It also makes it nearly impossible to pass along our experience because each coffee is just too unique to say anything definitive.
At the same time, roasting every coffee more or less the same denies the reality of the remaining 20% that is different: density, organic acids, and lipids to name a few. When we roast coffees all the same we miss out on much of the beauty that manifests itself in the final cup.
Resist the Fool’s Choice
This tension can seem impossible to resolve at first glance, but that’s a False Dichotomy. It’s an Either/Or choice, a Fool’s Choice, that we can refuse to make. There is an Option C, and that’s what we’d like to present to you today. We created our Roasting Framework that stands in the gap between roasting every coffee the same and treating each one as completely different. Our Roasting Framework lives in the tension between these two opposing views and, we think, reflects reality more completely. It’s not just the middle path, it is the higher path.
Step 1: Treat All Coffees the Same Until First Crack
During the first 2/3 of the roast, we’re really just adding sufficient heat to the system to facilitate a chemical reaction. Because coffees are over 80% identical, we recommend treating them as more or less the same up until First Crack. The specifics will depend more on your roasting machine than on the coffee, so we can’t make specific recommendations here like we do with our clients. However, if you follow the remaining steps we promise your roasts will be 95% as good as they can be on the first or second try.
Pro Tip – If you’re going to multi-task, we suggest doing it during this portion of the roast.
Step 2: Treat All Coffees as Different After First Crack
Once First Crack begins, we recommend mono-focusing on the coffee as opposed to the multi-tasking you may have been doing for the first 2/3 of the roast. Don’t stress! This part only last 2-3 minutes. Treating every coffee as unique after First Crack is helpful because this IS the chemical reaction we’ve all been waiting for; adding a steady amount of heat so the transformation fully takes place. Precisely what each coffee needs will be different, but you’ll likely find yourself making gas pressure changes every 15-30 seconds to keep things rolling smoothly.
Pro Tip – Aim for a smooth ROR curve as shown above. Think of it as a sign that the chemical reaction is taking place in a smooth, controlled fashion as opposed to fits and starts.
Step 3: Airflow – Set It and Forget It
Yup. You read that right. But why? The short answer is – during triangulation none of the Q Graders we tested (including Michael) could consistently identify the airflow changes and correctly attribute them. As in, sometimes the wrong cup was called out as different and other times the correct cup was called out, but it was labeled as higher airflow when in fact is was lower. Plus, a lot of roasting machines, like the Probats we cut our teeth on, don’t allow for airflow changes mid-roast. If it’s so critical, how are so many roasters cranking out delicious coffee without changing it.
Pro Tip – If you’r roaster has airflow control, set it a 50% (half-way between fully open and fully closed) and just leave it. If all you have is a baffle in the exhaust tube, do the same. Set it, forget it, and tinker with something that more consistently affects final cup flavor.
Step 4: Use a Consistent Framework for Gas Changes
During the first 2/3 of the roast, we’ve recommended treating all coffees as the same, so it’s no surprise that we’re suggesting you use a consistent framework for those gas changes. In general, we recommend 3 changes: at 320, 340, and 360. This allows enough time for heat to be added before the Color Change as well as enough time between the last gas pressure change and First Crack to ensure the reaction takes place smoothly. Check out our Roasting Framework for a more comprehensive look at those changes.
After First Crack, we’ve suggested treating every coffee as different, but that doesn’t mean making changes in a haphazard fashion. We recommend making the first gas pressure change 1:00 minute after First Crack and every 20 seconds after that (1:20, 1:40, 2:00 etc). Make your last gas pressure change at 23% Development Time Ratio (DTR), shut the gas off at 24% DTR, and drop the batch at 25%. Is this perfect? No! But yes, it is perfect.
Just kidding, of course not. However, you’ll learn a lot about the coffee and it will tell you how to adjust things moving forward.
Step 5: Choose a Batch Size That is 60% of the Stated Capacity
Many roasting machine manufacturers brag about their machine capacity, but there’s a difference between “can turn brown” capacity and “can make taste good” capacity. If your goal is to turn the coffee brown only, we’re amazed you’re still reading this. Way to go! If your goal is to make the coffee taste good, we recommend starting with a batch size that is 60% of the stated machine capacity. Especially if you’ll be roasting light or medium single origins. For blenders and darker roasts, it’s less critical because the coffee will be sufficiently developed, even at a larger batch size.
Pro Tip: If your machine’s capacity is stated in kilograms (kgs) try roasting that many pounds (lbs) and see what happens. You might be surprised at the flavors you get. (Example: Roast a 12 lbs batch on a 12 kg roaster and a 22 lbs batch on a 22 kg roaster. It’ll be fun!)
Step 6: Choose a Starting Gas Pressure That is 80% of the Stated Capacity
In a similar vein, the max gas for many machines actually scorches the coffee and causes other roast defects. Yes, it will move a massive batch through the roast curve towards First Crack, but at what cost? When dark spots start appearing on the beans or coffees taste burnt even at a lighter roast, you’ll know you’ve overshot the mark. Plus, if you’re roasting a batch that’s 60% of the stated capacity, you’ll only need 80% to move it AND make it taste good. Any more and the coffee will fly through the roast curve.
Pro Tip – Pull coffee out during the first 4-5 minutes using the trier and see if there are any visible scorch marks. If there are, lower the heat on the next batch and see what happens.
Step 7: Troubleshoot Predictably
As we’ve said, each coffee is different, especially after First Crack. However, that doesn’t mean we should throw the framework out the window when the coffee isn’t tasting good. The most common misses and their solutions are listed below:
PROBLEM: Too Dark – The final product hit 25% DTR but that caused it to overshoot the drop temperature you wanted
SOLUTION: Final Gas Pressure Change BEFORE First Crack – Your final gas change, at 360F in our Framework, should be lower. Leave everything else the same.
PROBLEM: Too Light – The final product hit 25% DTR but fell short of the drop temperature you wanted
SOLUTION: Final Gas Pressure Change BEFORE First Crack – Your final gas change, at 360F in our Framework, should be HIGHER. Leave everything else the same.
PROBLEM: Too Long – The overall roast and/or development time is too long, the roast tastes flat and/or baked
SOLUTION: More Gas Up Front and/or Fewer Changes – If there isn’t enough heat upfront (80% of max) the whole roast will lag. If there’s enough heat up front but the second part of the roast is too long, make fewer changes, especially after First Crack. For example, in our Framework, we have you lowering the gas every 20 seconds after First Crack. Make it every 30 seconds and you’ll see the roast maintain momentum through to the end.
Final Thoughts
Roasting is complex to be sure, but many have made it more complicated than it needs to be, especially for those starting out. The Curse of Knowledge holds true here; those who have achieved a Level 10 knowledge of something like roasting often have a hard time making it accessible to those with a Level 1 experience. We hope this helps you in your next roast and, more importantly, we hope you and your customers enjoy the next cup of coffee that much more.
Happy Roasting!