One of the most important decisions you will make while in the process of choosing a coffee roaster is, without a doubt, size. Determining what type of system to purchase can be just as difficult of a decision as there are many different types of Coffee Roasting Machines from which to choose.
The coffee roasting process involves heating the coffee beans to induce The Maillard Reaction. This is usually achieved with a mixture of convective and conductive heat transfer. But how does this help you decide what type of roaster is your best fit? Here at BURNS, we would like to provide some information about different roasting machine configurations; how each one transfer heat to the coffee beans, and the pros and cons of each design.
Solid Drum Roasters
Types of Coffee Roasting Machines that feature Drum Roasters are the most widespread roasters in the business. These machines roast coffee by heating a rotating drum. The beans receive both conductive heat transfer from the surface of the drum as well as convection from the ambient air. The simple design of a Drum Roaster lends itself well to a variety of heat source choices, flexible manual/automatic processes, longevity of its moving parts, and a variety of sizes. If you are looking for a dark roast profile, a drum roaster is the way to go; they produce more consistent dark roasts than any other type of roaster. One of the big drawbacks to watch with a drum roaster is that some beans will get burnt that are in contact with the drum. This makes it a little bit harder to duplicate roast profiles if you are not used to the specific roaster; however, there are some work arounds in the design of the drum to lessen this.
Single Wall Drum
The single wall drum roaster is your typical drum roaster. It contains a burner that heats the drum from underneath as it rotates, and the drum in turn heats the coffee beans through conduction. This lends itself to inconsistent roasts batch to batch because of the energy retained in the drum.
Double Wall Drum
The double wall drum roaster is a more refined drum roaster that uses the air between the two walls as insulation. Consequently, the beans have time to receive more convection heating. This technology allows the inner wall to stay a bit cooler during roasting, leading in turn to more consistent roasting and fewer scorched beans from batch to batch. The roaster seen below is a great example of this double wall roasting technique.
Perforated Drum Roasters
BURNS employs a unique take on the drum roaster. Instead of relying on the conductive heating from the inner wall of the drum, all BURNS Industrial Coffee Roasting Systems operate with a perforated drum. The perforated drum allows for more convective heat transfer during the roasting process. Through this increased airflow, the roaster can create a more even roast and a wider range of batch size flexibility. Additionally, the roasting process uses less heat than a traditional drum roaster.
Fluid Bed Roasters
If the drum roaster is considered the superior dark roast machine, the fluid-bed is the exact opposite. In general, fluid-bed roasters will roast the coffee faster and with less energy than drum roasters. This lends itself well to lighter roasts as it tends to retain more complexity and acidity than the drum roasters. Fluid-beds can do this because they rely solely on convection to roast the beans: air is pre-heated and subsequently pushed through a column of coffee beans. This airflow makes the beans float on a “bed” of hot air. Fluid-beds are known for more consistency, retention of flavor, and small footprint. However, they are a lot more complex than their drum counterparts, leading to more expensive machines, difficult maintenance, and limited capacity. Also, most fluid-bed roasters do not have the option to inspect the beans during the roast.
There are many decisions that go in to choosing a roaster, but the important part is mastering your craft once you do decide. Many coffee roasters swear by their preferred design, mostly because that is the one with which they are the most comfortable. Feeling overwhelmed by all the options? Send a message below, email to [email protected], or call (877)-683-8113 to speak with one of our experts. We are happy to address any questions or concerns you may have during the roaster selection process.