Prototype Testing – Part 2: Cacao

2011 August 24
by Joe Johnston

One of the major goals of the roaster project has been to design a roaster with enough flexibility to be able to optimally roast a variety of products. The most important is coffee, of course, and if designing a multi-roaster in any way compromises the ability to roast coffee, I will abandon the idea. However, it seems as though by varying certain parameters, one could also roast cacao, malted barley (for beer or distilled spirits), and nuts.

The first alternate product that I wanted to test for dynamic behavior in the prototype is cacao. Cacao is roasted at a lower temperature and for a longer time than coffee. It is also more delicate in terms of physical structure.

We started by cleaning all of the coffee out of the roaster bowl.

Next, we added 35lbs. of mixed, unroasted cacao “beans” to the bowl. This is the same batch size we consider to the be the nominal maximum.

We ran the bowl and found that the cacao behaved very similarly to the coffee with an optimum rotational speed of approximately 90RPM. The flow was very even and it appeared that the cacao was not being fractured in the process. This was something cacao experts who follow this blog had been concerned about.

We stopped the bowl and inspected the cacao for chipping and fracturing, which we found no evidence of. While this was just a single series of tests, we were encouraged that the roaster has the potential to roast cacao.


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