Roaster v. Roaster Comparison

Roasting on the Bellwether Roaster Compared to Traditional Drum Roaster

The roasting process on a Bellwether fundamentally similar to the roasting process on any other high-quality commercial roaster: The beans are held in a drum-shaped roasting chamber and exposed to hot air while being mixed using a rotary agitator. This process is used in traditional open-flame drum roasters, like the Probat and Loring. Proponents of open-flame drum roasters will claim they have more conductive energy transfer. While this is correct, all roasters use primarily convective heat transfer, and all use some conduction.

This continuity in the roasting process is by design. At Bellwether, we think traditional roasters produce good coffee — they just do it in a way that doesn’t provide the consistency, control, ease of use, and planet-friendly processes that the Bellwether Roaster provides.

Traditional roasters use a single-pass design, which takes cool air that is flash-heated to roast the coffee, then exhausts the air through ventilation stacks. The incoming air is of variable temperature, making it challenging to replicate precise roasting processes. Compared to the Bellwether Roaster, traditional roasters have little thermal monitoring, which makes it challenging to know different heat measurements throughout the machine at any given moment.

Removing External Variables

The Bellwether Roaster takes the exhausted air, cleans it, and reuses it. This process provides a hot, stable temperature of the air that’s being recirculated inside of the machine. The Bellwether Roaster is well-insulated, has twelve thermal probes, and multiple pressure sensors installed throughout the roaster to allow for precise monitoring and control of the roasting process. These innovative design advances remove most of the external variables that have historically made profile replication challenging.

The control mechanisms of a Bellwether Roaster are so good, a Head Roaster can now design a roast profile and the profile can be executed on any Bellwether Roaster, anywhere in the world, precisely as intended. It’s no longer a requirement to become an expert in the operation of any single machine; now, the artisans of our industry can concentrate on correlating roast profile design to flavor profile results and perfecting their craft.

Using the Bellwether Roasters vs. Traditional Roasters

If you are accustomed to traditional roasters and are using a Bellwether Roaster for the first time, you should use the same basic principles. Your roast curve will look similar to those on other roasters with a couple of notable differences:

· On a Bellwether, you define the result — not the process. You will not be adjusting gas valves or airflow in real-time, but instead, you will be drawing a curve on the Bellwether app and then tasting the results. You can adjust the roast profile curve to more precisely hit your flavor goals. When you’re happy with the result, you can repeat the profiles exactly, experiencing consistency like never before.

· Like all machines, there are physical limitations to what roast curves the machine can follow. While the Bellwether has ample power, just like conventional roasters, laws of physics still apply.

· From 0—1 minute, 95% of the curve’s shape is determined by the batch size and charge temperature.

· The rate-of-rise of the coffee temperature will peak early and tend to decline as the roast proceeds.

· Since metal stores much more heat than air, Bellwether uses the temperature of the metal roasting chamber to determine the ideal preheat temperature (i.e. the “charge temperature”). Other roasters measure air temperature, which is a less reliable predictor of how much heat is stored in the roaster. As a result, the charge temperature on a Bellwether Roaster is usually around 75°F lower than you would see if you were using air temperature as your measurement.