Roasting coffee is a nuanced process that involves applying heat to green coffee beans to draw out their natural oils and roast them to a point where they become that deep brown color we’re all familiar with. There are many ways to tweak the roasting process, depending on the quality of the beans used and the darkness of the roast that you want to make. The coffee roaster is the tool we use to make magic happen and prepare deliciously roasty fresh coffee beans for your drinking pleasure.
So How Does a Coffee Roaster Work?
In short, a coffee roaster works by applying heat to green coffee beans to get them to release their oils and heat through. Some roasters are powered by coal or gas fires, while others utilize the power of infrared heat to provide a more even heating. The heating process is controlled to slowly warm beans throughout the roasting process.
Heat is applied for varying lengths of time, depending on the roast we want to achieve. Lighter roasts receive heat for a shorter period of time to maintain a more floral, less roasty flavor. Darker roasts spend a longer time in the heat so that more oils are drawn out and the beans take on a darker and smokier quality.
However, this can’t be done in any old way, or you’d end up with unevenly roasted beans of questionable flavor. Or worse, a pile of charred bits that were once coffee beans.
Thus, motion is a critical component to the roasting process. Home roasters will often use simple roasters that resemble air popcorn poppers to get the motion they need. Larger operations like ours employ commercial drum roasters that have a rotating drum that keeps coffee beans moving while they heat up.
Drums can be smooth or perforated, upright or horizontal, depending on the make of each individual roaster. They all work the same way - by rotating constantly during operation to keep beans moving. Centrifugal force presses beans evenly against the sides of the drum to help prevent layering and to expose each bean evenly to the heat source.
Lastly, an exhaust system works to remove smoke and bits of coffee skins from the roaster to keep beans fresh and free of debris that builds up during the roasting process. This step is crucial to providing the finished, ready to drink roast.
So the next time you fill up your mug, consider the coffee roaster and the important role that it plays in transforming raw coffee beans into the roasts you love.