During winter time coffee roasting on the balcony is quite cold and icy. Fortunately, we have a large garage that is perfect for coffee roasting
The drum has a capacity of 5 lbs coffee beans in one session
The rotisserie spear is fastened to the drum
The grill is fired up and the rotisserie starts running
An electric motor is turning the drum with constant speed during roasting
The roasting process takes approximately 45 minutes
Until the beans start popping maximum power is used
The popping at first crack starts when the beans’ core temperature is 390 F (200 C)
You may open the lid to inspect the roasting but be careful to keep the drum hot
There is considerable smoke development at second crack when the core temperature has reached 440 F (225 C)
The roasted coffee is cooled on tin pans
During roasting chaff is produced by silver skin separating from the beans
Chaff may be removed manually or by careful blowing of air, but this may be both time consuming and messy. Therefore I have constructed a simple prototype of a chaff removing machine.
It is made of a ventilation tube with a perforated lid in the lower end, here seen upside down.
Roasted beans with all the chaff is poured into the upper end of the tube
The vacuum cleaner tube is fastened to an air tight lid in the upper end, and the vacuum cleaner is started. The chaff is easily sucked up by the vacuum while the beans remain in the lower end of the tube.
The roasted coffee beans are stored in vacuum containers to keep them fresh and prevent oxidation