About Fluid Bed Roasting
Also known as Hot Air Roasting or Air Roasting
AIRPRO coffee roasters by ASHE use Fluid Bed Technology and are classified as hot air or air roasters. Fluid bed air roasting is a superior form of coffee roasting that was technically not possible when legacy drum style coffee roasting systems were originally developed in the 1800’s. Not until efficient electric blowers and electric heating elements became commercially available, was it possible to develop a cost effective and production worthy fluid bed coffee roasting system. AIRPRO roasting systems by ASHE use a stream of high velocity heated air, delivered from our patented High Residence Time heating system, to levitate the coffee beans and circulate them in a bath of hot air. Heat transfer to the beans is direct, via convection, allowing uniform heating of the individual beans. Air roasting with a purpose built ASHE hot air roasting system, designed specifically for roasting coffee, provides a consistent uniform roast, batch after batch. Roast times on the AirPro-22 roaster with a full 22 pound load of beans range from 14 minutes with a cold roaster to 11-12 minutes with a fully heated roaster. Easily roast five 22 lb batches of green per hour for an hourly capacity of 110 lbs. The AirPro-11 can easily roast five 11 lb batches of green per hour for an hourly capacity of 55 lbs.
As the coffee beans are levitated in the the hot air stream, they roll and tumble in super heated air, which causes unwanted by-products of the roast (burnt chaff, under size or broken beans, etc) to be expelled by the convective/lifting action of the hot air. In addition, AIRPRO fluid bed hot air roasters by ASHE come with forced air cooling outside the roast chamber, which produces rapid cooling, while allowing the next roast batch to be quickly loaded into the roast chamber immediately after pouring out the fresh roasted batch into the cooling system. This provides for an efficient production process for high volume roasting with minimal production labor.
The major differences between Fluid Bed Roasting and Drum Roasting
Removes Unwanted By-Products
Unwanted by-products of roasting coffee (chaff, loose debris, silver skin), released from the beans during the roasting process, is roasted and burnt with the beans during the traditional drum roasting process. Chaff and other debris are not quickly and efficiently removed from the drum environment and therefore remain with the coffee beans during the roasting process. Chaff and debris are burnt during the drum roasting process and contribute unwanted bitter flavors to the beans. In the AIRPRO fluid bed system by ASHE, Chaff and other unwanted debris is immediately removed from the roasting environment, lifted away in the convective hot air stream, allowing for a clean, fresh-tasting roast.
More Flavor
The longer coffee beans are roasted, the more flavor oils are reduced. ASHE Roast times are typically under 15 minutes for a full 22 lb (10kg) load and 10-12 minutes for a full 11 lb (5kg) load. The patented ASHE High Residence Time (HRT) heating chamber allows for efficient heating of the air stream resulting in lower roasting times.
Consistent Temperature
The ASHE roaster provides a consistent temperature to all the beans in a batch. Because of the “fluid” motion formed by the hot air being pumped in, the beans are surrounded by high temperature air and constantly moving within the roasting chamber. The fluidized motion ensures each bean is exposed to the heated air to exactly the same degree, creating a very uniform roast. In a drum roaster, the beans are stirred with a mechanical arm which does not distribute the beans evenly in the heat, causing some beans to be over-roasted. The fluidized motion of the beans in the AIRPRO roaster also provides for efficient heat transfer directly from the hot air to the beans via convection, rather than less efficient indirect heat transfer by conduction of heat through the drum wall.
Forced Air Cooling System
AIRPRO roasters by ASHE come standard with a forced air cooling system. In most fluid bed roasters the beans are cooled in the roast chamber by means of a water spray. With the ASHE AIRPRO system, the beans are tipped into the cooling system as soon as the roast is completed, and cool down to a point where no further roasting is happening within seconds, and continue to cool to touchable within just a few minutes. This give the roaster the advantage of simultaneously starting the next batch of coffee, which can be loaded in the roast chamber immediately after the previous one has been tipped out, allowing for continuous production roasting. The cooled coffee is removed from the cooling tray long before the next batch is ready to tip. The cooled coffee can then be immediately packed to preserve freshness.
Easy To Control
The AIRPRO fluid bed roaster by ASHE is much easier to control than a drum roaster. The operator can visually observe the coffee at all stages of the roast, rather than pull a sample multiple times during the roast to see the progress of the beans in the drum. Roasting can be done entirely and precisely by temperature if desired, though most roast experts will also want to use their eyes, nose, and ears to monitor the roast, which is how one becomes a roast expert rather than just a roast operator. However, this level of expertise is not necessary with an AIRPRO fluid bed roaster by ASHE. The learning curve is simple to master compared to the drum roasting process. No special training is required to quickly become 100% proficient with the AIRPRO fluid bed roasting process.
