[Homeroast] Homeroast Digest, Vol 25, Issue 23

Mike Davis mldavis2 at sbcglobal.net
Tue Feb 23 16:40:13 CST 2010

It would appear that each roaster and each bean should be evaluated 
individually.  Obviously some beans just don't look the same at 
allegedly the same roast level.  Many beans can appear to be at 
different roast levels in the same batch.  Immature beans come out 
lighter than mature beans, for example, and dry processed beans are also 
subject to variations in appearance.

I'm not completely sold on using temperature because there can be too 
many variables with that as well.  Commercial roasters are more suitable 
for temperature measurement because of larger batches and longer 
roasting times combined with more uniform placement of temperature 
probes.  Home roasters have accuracy issues with probe placement since 
temperature probes are not often included within the roasting container 
itself due to the methods of agitation required (i.e. turning drums, air 
flow blowers, etc.)  In addition, anyone who cooks knows that you can 
achieve a thoroughly cooked item with either a long, slow low heat 
method (crock pot, simmering) or higher heat (broiling, searing).

So a final roast temperature of, say 450F, might result in the same 
level on a commercial gas-fired roaster day in and day out, but it 
probably has no direct correlation to a FreshRoast, iRoast2, Behmor, 
Gene, Hottop or your backyard grille.

In my limited experience, I rely on a combination of sound, time, 
appearance and relative temperature readings from a fixed probe.  Tom's 
bean chart is my best baseline for comparison until I can find someone 
to really teach me how to do it 'by the numbers.'  In the meantime, I'm 
creating my own pig-trail down the jungle path to coffee nirvana with 
occasional sideways glances in the bushes for snakes.

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