Home Coffee Roasting 緑コーヒー豆の自家焙煎

I do not remember when I started home roasting green coffee beans but it was sometime ago. I started with  an electric popcorn popper, then over time used 4-5 different hot air roasters (many broke, some were discontinued. Only one hot air roaster is still working but I am not using it any longer). I also had a drum  roaster (Behmor 1600) on which I upgraded the control panel and it is still working but is a bit unreliable.  I am currently using a “Gene Cafe” roaster (picture #1).  I am not sure this should be classified as a drum or hot air roaster. It is probably more along the line of the hot air roaster.

General summary: Most roasters are too loud to hear the both the first and second cracks which are important determinants of the stage of roasting the beans have achieved. The roasters also produce a lot of smoke so they have to be used outside or in very well ventilated spaces. Over time, however,  I have discovered that the shape of some of the roasters make it possible to temporarily attach a drier vent duct to the roaster to channel the smoke directly up to the vent hood over the stove. With this temporary set-up the roaster can be used indoors under the hood. All the roasters, especially hot air roasters, are quite sensitive to ambient temperature as well as the voltage fluctuation. Some models have, although limited, programable temperature profiles. For some roasters the amount of green beans you can roast is also limited.

1. Hot air roasters: This type is easy to use but you cannot hear the first or second cracks to judge the roasting stages due to the loud noise made by the machine.

2. Drum roaster: Behmor 1600 (the current model is 2000AB plus) is the only drum roaster I have used. This is composed of a wire mesh drum and a radiant heat source in the back of the drum. This is a very quiet machine and I could hear both first and second cracks. There are some roasting programs you can choose or you could use your  own temperature profile. This worked well but their “smoke suppression system” does not really work and there was no way to attach a drier duct for venting so I could only use this machine outside. In addition the chaff collector is not very convenient and, in general, cleaning is not easy. The capacity is unusually large and it can roast up to 1 pound. The newer model appears to have more controls and other improvements. Over time and with much use the machine became unreliable. The drum would stop turning in the middle of roasting. I would have to shut off the machine and then restart it. As a result I would lose control of the timing of the roast and the beans would come out over or under roasted.

3. Current roaster: Gene Cafe, It has an off-axis glass cylinder drum and you can clearly see the beans while roasting (picture #1) . The chaff collector is large and quite good and allows the attachment of the clothes drier duct and can be used in-doors under the hood. When used outside without the noise of an exhaust fan under the hood I can hear the first crack very well but the second crack is difficult to hear. When used in-doors with an exhaust fan going, I cannot hear either of the cracks. It can roast up to 8oz of coffee in one batch. I am reasonably satisfied with this roaster but cooling takes a long time and chaff removal is not perfect.

To compensate these two short comings, recently, I added another coffee roasting contraption which is the “coffee cooling tray” (picture #2). This is rather simple device but works well. The fan and motor are located at the bottom layer sucking air from top and out. The top sieve has a coarse metal screen where the hot coffee beans get placed (#3) and the middle sieve has a fine metal screen to catch the chaff (#4).

A tiny metal “shovel” is included for stirring (#3).

While cooling, stirring the beans further removes the chaff which is collected in the second sieve (#4).

The hot coffee beans cool down very quickly and quite more chaff comes off. One of the major difficulties is that the Gene Cafe is not designed to be used with an external cooler. After it goes into the cool down cycle, the temperature has to come down below a certain level (I have not determined the exact temp) before you can stop and remove the cylinder/drum which defeats having the external cooling tray. The only way you can remove the cylinder while it is hot is to force it off (by unplugging the machine), removing  the cylinder and dumping the hot coffee beans into the cooling tray. This may not be good for the roaster, however. So, this is what I came up with.

1. I line up an extra roasting cylinder and the cooling tray turned on next to the roaster.

2. After the roasting is completed, I put the roaster into the cooling cycle. Wait about 1 minute until the temperature comes down below 400F then unplug the machine (making sure the cylinder position allows me to remove the cylinder when it stops). 

3. I remove the cylinder and dump the hot coffee beans into the cooling tray and place the spare cylinder back into the roaster(You could put back the original cylinder after dumping the beans but this is difficult since the cylinder is hot and seemingly expands enough to make putting it back more difficult.)

4. Plug the roaster back in and turned it on.  Start “roasting” and immediately turn it to the cooling cycle and let it cool down until it stops. (I am hoping this procedure is the least harmful for the roaster).

So, is all this effort worth it? Although I think I know what I like in my coffee/expresso drinks, I am not sure I can differentiate beans cooled quickly vs slowly in the roaster cooling cycle.  Other factors such as beans, roasting level, grind, how the espresso is brewed may make more significant differences. Never-the-less, I try to do everything in the right and consistent way so that I can have coffee we like.