[Homeroast] Start of exothermic reaction

John Nanci john at chocolatealchemy.com
Tue Sep 15 12:46:26 CDT 2015


My experience is somewhere between 1st and 2nd.  Definitely at 2nd and 
self sustaining at 3rd :)

One observation I'll toss in relates to the differential between the 
roaster temperature and bean temperature.  Meaning you can at most any 
stage turn off your roaster, and if monitoring the bean temperature, 
watch it steadily climb as the drum and beans equilibrate in 
temperature.  This makes determining the endothermic/exothermic 
inflection really difficult to determine as it's near impossible to 
separate  the rise from equilibration from exothermic reactions.

John

On 9/14/2015 1:30 PM, Michael Rasmussen wrote:
> On Facebook I saw a post,
>    "Fun coffee fact: First crack of coffee is endothermic, i.e., the
>    reaction takes external heat energy. But second crack is exothermic:
>    The beans start generating their own heat."
>
> And thought, "no, first crack is exothermic too." Then I went online
> to verify.  But it seems exothemeric reactions start even earlier.
>
> One source states it is occurring when the internal bean temp gets to 375F.
> Of course, sources are not consistent.
>
> What's the consensus here about the start of exothermic phase?
>


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