[Homeroast] Storage right after roasting

Mike Davis mldavis2 at sbcglobal.net
Sat Aug 16 12:31:25 CDT 2014

I think the big unknown in storage techniques is the effect of oxygen 
(if any) to the resting process.  Over a long enough time period, coffee 
will go stale of course when exposed to oxygen.  But on the other side, 
we know that "resting" can enhance the flavor. So the real question 
would seem to be what happens during the "resting" time and if the 
presence or absence of oxygen is responsible for the improvement.  
Logically, if CO2 is a result of chemical process taking place during 
"resting" then oxygen should be nearly non-existent.  It is possible 
that cooling could pull oxygen back into the beans.  But storage 
immediately after cooling would seal them from additional oxygen as the 
beans exuded CO2 which would expel oxygen from the container for a while 
before oxygen begins to work its way back in when CO2 pressure is 
reduced to equal.  So I assume (perhaps incorrectly) that the favorable 
chemical processes that enhance coffee during resting are a "coasting 
effect" of heating and continue to completion in the (nearly) total 
absence of oxygen.  In other words, they are not an oxidation process as 
such requiring oxygen.

So my system (such as it is) is based on those assumptions.  Put the 
beans into a light-tight container (AirScape canister) with minimal 
holes just sufficient to allow exit of CO2 overnight, yet so small that 
the greater CO2 pressure probably prevents incursion of oxygen as the 
CO2 exits.  Then seal the canister once the CO2 has stopped. There 
should be little or no oxygen present except what little might remain in 
the beans, and the coffee should complete the chemical "coast" and then 
more or less stop, waiting for the lid to be unsealed.  I think this is 
the idea behind coffee that is weeks old (or older) on store shelves - 
one way CO2 valves that exclude oxygen.  Once my beans are loaded into 
the hopper, then of course, there is abundant oxygen and staling begins.

That's just what seems to work for me.  I'm always open to better 
suggestions and ideas.

Mike Davis

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