Roasting Profile for Hard Bean Coffee
For hard beans, especially when roasted beyond the second crack, I recommend an “S-curve” for the roasting process. (This is based on endless cupping trials and comparison of different roast profiles). After loading the beans into the drum, the bean probe will display a drop in temperature, which will bottom out at the turning point (TP). Hard beans will now be roasted with high initial heat. Until the start of the first crack, the heat inside the beans is endothermic; the beans are absorbing the supplied heat. Right before the start of the first crack, the heat inside the beans becomes exothermic and the beans start generating heat. At this point the operator has to reduce energy supply in order to gain control of the roast process (point I). After about two minutes of controlling the roast with low energy supply (less BTU), the operator can again increase heat (endothermic heat; the beans are again absorbing heat) to prepare for the finish of the roast. The start of energy increase can be seen at the point where the temperature curve is rising again (point A).
During numerous cupping trials, I have found that the ideal time between the start of the first crack and the end of the roast (I and End) is at least three minutes. The ideal roast time for solid drum roasters with
convection heat (airfl ow heat passing through the drum) is 12–15 minutes. With these roasters, roast times longer than 20 minutes will produce baked flavors; roast times shorter than eight minutes will enhance sour notes. For solid drum sample roasters, the roast time can be done in 8–10 minutes. Drum roasters using infrared heat usually allow longer roasting times without affecting the quality of the roasted coffee. Fluid-bed roasting machines, which use the concept of transferring heat through a high-velocity airfl ow at a reduced temperature, usually allow faster roasting times.
convection heat (airfl ow heat passing through the drum) is 12–15 minutes. With these roasters, roast times longer than 20 minutes will produce baked flavors; roast times shorter than eight minutes will enhance sour notes. For solid drum sample roasters, the roast time can be done in 8–10 minutes. Drum roasters using infrared heat usually allow longer roasting times without affecting the quality of the roasted coffee. Fluid-bed roasting machines, which use the concept of transferring heat through a high-velocity airfl ow at a reduced temperature, usually allow faster roasting times.
After learning roasting the hard way—by using sight, sound and smell—I later discovered the important value of proper measuring tools, such as probes for exhaust, environmental and bean temperature. Anyone who operates a coffee roaster can replicate the experiments I’ve completed over the past years. Learning how to roast each green bean to perfection is just the fi rst step in creating that perfect cup
Source : ROAST MAGAZINE
JAVA PREANGER COFFEE ADDICT
Fadillah Satria
Comments
Post a Comment