Fluid Bed Roasting

ASHE Roasters use Fluid Bed Technology.  This is a far superior form of roasting to the more traditional drum roasting,  as is supported by our customers and their customers who come back time and again for the fresh-tasting roasted coffee.  Basically, fluid bed roasting is similar to the action you would see in a hot-air popcorn popper. The beans roll over in superheated air, and the unwanted by-products of the roast (burnt chaff, undersize or broken beans, etc) get expelled by the hot air draught. In addition, our roasters come with forced air cooling outside the roast drum, which gives almost instantaneous cooling and allows for the next roast to be in the roast chamber while the former roast is cooling.

The major differences between ASHE fluid bed roasting and drum roasting are these: 

• Drum roasters burn all the unwanted by-products of chaff and broken beans and they retain them in with the roasted beans. The smoke produced can give the beans a burnt after-taste, especially when making a dark roast coffee.  In the ASHE fluid bed roaster, these products are blown out of the system.
• The longer coffee beans are roasted, the more the flavor oils are reduced. Drum roasters can take 20 minutes to roast a 10 lb batch. ASHE coffee roasters take approximately a minute a pound to medium roast, just a minute or two longer to dark roast.
• 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 rotate up and down and around in the  air flow in the roasting chamber constantly, so that each bean is roasted to exactly the same degree.  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 ASHE roaster comes 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 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 that a new batch of coffee can be roasting in the roast chamber immediately after the previous one has been tipped out, allowing for continuous 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.
• Fluid bed roasting is much easier to control than with a drum roaster. The operator can observe the coffee at all stages, rather than pull a sample every few seconds to see where they are.  Roasting can be done entirely and precisely by temperature, if desired, though most roast experts will want to use their eye, nose and ears as well, that is how one becomes a roast expert rather than just a roast operator. However that level of expertise is not necessary with a fluid bed roaster, the way it is with a drum roaster, just much more fun to do.