What’s So Great About Hot-Air Roasting?
To drum-roast or air-roast? Posing that question alone could evoke a spirited debate among coffee roasters anywhere.
Since the advent of coffee roasting, people have been frying and sizzling coffee beans with an open flame over hot metal. In other words, for as long as coffee has been around, drum roasting has traditionally been the go-to method to transform green coffee beans’ chemical and physical properties into roasted coffee products. However, the more modern approach, hot-air roasting, has become the preferred heat transfer system for many roasters today. As it suspends the coffee in a convection current of hot air, the heated air can envelop every single bean evenly, resulting in an even and consistent roast.
What’s so great about hot-air roasting? Is it really the best method?
Consistent bean temperature and degree of roast
Hot-air roasting is favored for its precision in results. This is thanks to the fact that this method produces an even roast, not only between the coffee beans, but also inside the individual bean. Meaning that coffee roasted in a convection (hot air) roaster will have a uniform color from the outer layer all the way to the core. Even if they desire to take it to the edge of flavor development, they won’t compromise the clean, sweet flavors (i.e. no need to worry about scorching). This differs from a drum roaster, where the coffee is roasting on hot metal. The bean’s outer layer can heat too fast resulting in an uneven color inside the bean.
Consistent sweet, clean flavor
Different roasting methods give different results. Traditional drum roasting operates with a higher conductive heat transfer to make the chemicals react. It roasts the beans from the outside, known to leave you with a thicker flavor regardless of the origin of the coffee. Drum-roasting your beans will develop a heavier, sometimes oilier, and denser taste. This flavor profile may not be sought-after, but this method will always hold a soft spot for traditionalists.
On the other hand, Hot Air Roasting utilizes 100% convective heat transfer to elevate the aromatics in coffee. Convection roaster keeps the coffee beans moving and rotating with a perfectly controlled hot air flow to produce an even roast. During the process, hot air forces out of the chaff that would otherwise burn into the beans and mask the true profile. The end result is a clean, smooth taste that many coffee drinkers love. Roasters and drinkers who have tasted hot air roasted coffee beans can attest they can taste the noticeable improvement in flavor to drum-roasted beans.
Eliminates the undesirable effects of drum roasting
The hot-air roasting method is preferred by many modern roasters, as roasters have total control over the entire roasting process. Hot-air roasting provides better control for the roasting process, avoiding scorching the beans, among other reasons.
Hot-air roaster allows a more precise Between Batch Protocol (BBP) by taking away one parameter that has always been a guesswork in a traditional drum roaster: drum surface temperature. It is virtually impossible to measure drum surface temperature in a traditional drum roaster, but this measurement is unnecessary in a hot-air roaster since the drum is never directly heated by the burner. This way, the roaster can easily duplicate batches of coffee beans, recreating the same color, flavor profiles, and aroma.
Whether you continue producing drum-roasted coffee or venture into the world of air-roasted coffee, it remains equally important to choose a quality coffee roaster.
Be sure to buy from a trusted roaster that can help find you a machine suited to your unique needs.
Berto’s roasters are guaranteed to deliver top-quality coffee, no matter your roasting preference. Learn more about our roasters.