[Homeroast] Storage with gasses; and the Behmor question

Jon Rosen jon at jonro.com
Wed Aug 27 16:12:39 CDT 2014


I wonder if the beans should be fully exposed to oxygen for the first 24 hours? I suspect that the beans need O2 at first in order to form flavor compounds. How much O2 is required? If the container were loosely sealed, would there be enough O2 to do the job? After that, it seems like O2 needs to be eliminated to help prevent secondary reactions that continue to oxidize the good flavor compounds into more rancid elements. I believe there is a very expensive wine preservation system that uses argon to keep oxygen from turning the wine, so the idea is sound. I have a feeling that a vacuum system would be a much less expensive way to keep the beans relatively oxygen-free for the next week or two.

Jon

On Aug 27, 2014, at 2:18 PM, John Nordling <john.nordling at gmail.com> wrote:

> Thanks Mike.  That is great info, and also, probably the best problem I've
> seen.
> 
> With respect to gases mixing, i would say that we're diffusion limited in
> how fast they'll mix, but that assumes an undisturbed atmosphere, which we
> probably don't have. We have room air movement, which I think makes this
> whole discussion moot, but I do love a good, nitpicky, largely pointless
> discussion about chemistry - it's what I do - so here goes . . .
> 
> My feeling as a chemist is that the offgassing of the CO2 is rapid enough
> that during the first 12-24 hours, in a container with a smallish opening
> (think mason jar with a loose lid, or perhaps a ketchup bottle with no lid)
> little to no O2 gets to the beans.  They're effectively at positive
> pressure from the CO2 evolution.  After that, if the container has
> something to minimize the movement of air into/out of it (as simple as
> cotton batting in the opening), there will be some mixing over time, but it
> will be on a slow time scale (order of days).  Assuming CO2 continues to
> evolve, albeit at a slower rate, I think it would keep the O2 largely out
> of the picture.  Open jar on the counter - lots of oxygen.
> 
> I wonder if putting an argon blanket over my beans would do anything to
> help preserve them.  I might give that a try, just for fun.  Roast 1/2 lb
> or so, rest overnight open to atmosphere.  Drink 1/3 (because, why not),
> put 1/3 in an open top jar with cotton, put the last 1/3 in a jar with an
> argon blanket.  Store in a cupboard for 2 weeks, then brew up both batches
> to see if the flavor is better preserved in the Ar blanketed portion of the
> batch.
> 
> Stay tuned for details . . . I'm not sure if I have an Ar tap available in
> my lab.  I haven't needed one before.
> 
> -John
> 
> 
> 
> ~~
> "Can't believe how strange it is to be anything at all."   Neutral Milk
> Hotel, *In the Aeroplane Over the Sea*
> 
> Email:  john.nordling at gmail.com
> 
> 
> On Wed, Aug 27, 2014 at 12:57 PM, Mike Davis <mldavis2 at sbcglobal.net> wrote:
> 
>> "If you fill a container with two gases of different densities, they will
>> mix, and fairly quickly.  The speed will depend a little bit on the
>> difference in density of the two.  Over a period of time, the mixture will
>> become a completely homogeneous mixture." - Mike Koenig
>> 
>> I won't disagree here on the scale in which we are storing coffee.  But of
>> course gasses of different densities do in fact separate as we see in large
>> scale with earth's atmosphere.  That's what causes a He-filled balloon to
>> rise in our atmosphere of N2 and O2 and CO2.  A technicality.  My storage
>> procedure takes into account the fact that CO2 is being given off which
>> reduces the relative percentage of O2 and exerts a slight pressure thus
>> forcing the mixture of atmospheric gas and CO2 out.  The resulting mix is
>> higher in CO2 and lower in O2 and should reduce the rate of oxidation of
>> the coffee during storage.  The obvious question is how much did you roast
>> and how long must you store it?  Ar would work, and I believe that apples
>> are stored under N2 for a considerable time.
>> *******
>> John Nordline asked what I would want to add to the Behmor that isn't
>> there.  At this point with my roasting, I don't know of much.  There are
>> some things that would be nice to be able to do that commercial roasters
>> have available, but they aren't practical on small batches.  So I'll be
>> overly picky and try to answer.
>> 
>> For example, the Behmor has temperature sensors in the roast chamber wall
>> and the exhaust.  These are not the direct temperature of the bean mass
>> which is what commercial roasters rely on.  But they can be used in a
>> relative manner to profile roasts once the relation between them and the
>> bean mass is established for a given roast weight.
>> 
>> Cooling is fairly efficient with the cooling fan blowing a good airstream
>> through the roaster.  Faster cooling isn't really feasible unless you
>> remove the cage and rig up a cooling fan system of your own.  This would
>> eliminate having to cool both the bean mass and the interior chamber of the
>> roaster.  There is some coast down as the heating elements switch off.  But
>> you can cool manually if you think it really matters.  The Behmor delivers
>> beans that are essentially room temperature in 12 minutes and that's been
>> good enough for me.
>> 
>> The roast curves built into the Behmor have been criticized as not being
>> tailored quite right for varying bean types.  Now with heating element
>> controls (0%, 25%, 50%, 75% and 100%) you can create your own curves with a
>> bit of experimentation.  No single curve is "right" for each of the
>> hundreds of bean choices at SMs, so it's still as much art as science.
>> Even with the ability to program your own temperature on the iRoast2, I
>> ended up using one program and stopping the roast manually by the bean
>> color and time from 1C.
>> 
>> The Behmor is designed for safety which has frustrated some of the users
>> who roast very dark batches by limiting total time on the timer.  That's
>> really only a problem if you are trying to roast a full pound and want a
>> Vienna roast because there are time limits beyond which the roaster will
>> not run.  I suspect Behmor has done this for safety reasons because once
>> past 2C, ignition can begin very quickly.  The new 1600-Plus, as I've
>> mentioned, has a 75% safety feature that blinks the LED lights for 30
>> seconds.  You must press "Start" again to remove the flashing lights and
>> return the timer to normal.  Some complain that the timers could be
>> extended.  I haven't found that to be a problem and can easily over-roast a
>> batch if I want to do so.  Typically I roast 1/2# on the 1# setting which
>> gives more than enough time, and manually stop the roast at the moment I
>> think is right for that particular bean.
>> 
>> Visibility of the beans is not really necessary, but it could be perhaps
>> better.  You can see the beans clearly, but the actual color of the beans
>> is distorted because of the red-orange glow of the heating elements.  Beans
>> can appear lighter than they are toward the end of the roast.  I now rely
>> on timing of the cracks and subsequent post-1C times nearing 2C, and little
>> or none on bean appearance.
>> 
>> So I love my Behmor 1600-Plus.  It took me a bit of time to transition
>> from my iRoast2 but I'm in control now.  It has good smoke control, good
>> cooling, it's quiet and cracks are plainly audible.  It cleans easily with
>> a vacuum cleaner.  I don't think you can beat it for the price.
>> 
>> My only complaint is that I bought the roaster at SMs, and they sent me 8#
>> of coffee which overstocked my pantry and caused me to miss some of the
>> great Africans that came in shortly thereafter.  :-)
>> 
>> Mike Davis
>> 
>> 
>> 
>> 
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