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