Roasting Technology

by Sean Quinn

We have come a very long way from our beginnings roasting with a cast iron skillet on our stove. While I'm proud of my now-defunct, MacGyver-esque early roasting apparatuses, we are even prouder to be roasting on a Coffee Crafters Artisan 3e, automated using a Hermetheus Co-Pilot kit.

Why are we so proud? In short, our roaster excels at churning out top-tier small batch coffee with extremely reproduceable results. Want more explanation? Say no more:

Fluid bed Roasting

Our roaster uses air to heat and agitate the coffee beans, a method known as fluid bed roasting. This means that (nearly) all of our roast energy is efficiently and evenly transmitted to the beans by the air (convection), contrary to a traditional drum roaster where a significant portion of the heat is transferred through conduction with the drum.

This poses more of a problem the smaller ones batches get, whereas fluid bed technology performs best with smaller batch sizes (our 3e roasts up to 3lb batches, but I prefer the headroom allowed by 1kg max batch size).

Drum roasters are preheated to a charging temperature before beans are added, and overall system (beans+drum) heat levels have to be closely managed to avoid stalled and runaway roasts. Fluid bed roasting eliminates the drum from the heat system, allowing for much simpler automation protocols, as the system is much more reactive to heat input and less prone to uncontrollable momentum.

This means that the factors that affect roasts from day to day (leading to inconsistent bags on your end as the customer) are minimized, allowing the automation to follow as closely as possible to the reference profile.

Automation and Profiling

Every coffee has a unique flavor profile that has developed from a variety of factors, similar to wine. We have developed roast profiles for each of our beans, each with unique temperature targets at specific times during the roast in order to maximize the unique characteristics of that coffee.

Here's an example graph from a roast of our Honey Processed Costa Rica:

The foreground blues are the roast temperature (and deltaT), with the background blue lines being the reference targets. This is an ideal roast where the final two thirds match the reference nearly exactly.

If you've made it this far, congratulations! It's a lot to consider, but at the end of the day, you can rest assured that an incredible amount of consideration and care has been put into each Quinning Coffee, all you have to do is order it.