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Lambic Digest #0404
From postmaster at longs.lance.colostate.edu Sat Jul 23 03:14:16 1994
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From: lambic-request at longs.lance.colostate.edu (subscription requests only - do not post here)
To: lambic at longs.lance.colostate.edu
Subject: Lambic Digest #404 (July 23, 1994)
Date: Sat, 23 Jul 1994 00:30:12 -0600
Lambic Digest #404 Sat 23 July 1994
Forum on Lambic Beers (and other Belgian beer styles)
Mike Sharp, Digest Coordinator
Contents:
diffusion (Algis R Korzonas +1 708 979 8583)
Re: Lambic Digest #403 (July 22, 1994) (Nick Zentena)
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Date: 22 Jul 94 17:18:00 GMT
From: korz at iepubj.att.com (Algis R Korzonas +1 708 979 8583)
Subject: diffusion
Jim writes:
>matters. The Nalgene technical people have pointed out to me more than once
>that what a container is made of is not that big a deal. It is the closure
>where 99% or more of the gas diffusion occurs. We store media in PC bottles for
>months with no pH change, indicating little gas diffusion. Rubber stoppers
>probably aren't very good LONG term gas barriers, but I could be wrong. What
That's what you'd expect the Nalgene people to say. Ask the Corning people
too. ;^).
Regarding your assertion that "no pH change = no diffusion," I'd like to
investigate that. Mind you, my chem and physics are very rusty, so bear
with me. What's the % CO2 in the atmosphere? A couple of percent? That is
the % CO2 that the media in the container will try to reach to achieve
equilibrium. I don't think that this concentration will cause much change
in the pH. The % O2 in the air is, what, about 18%... that's quite a
bit more than CO2. Also, if I recall correctly, the rate of diffusion is
proportional to the difference in concentration across the permiable membrane,
so we would have a much faster rate of diffusion of O2 into our wort through
a plastic fermenter than CO2 diffusion into your media, no?
Incidentally, PC is twice as permiable to O2 as HDPE and just a little less
than twice as permiable to CO2.
I don't think the stopper itself allows much diffusion (even if it was very
permiable, it's almost an inch thick!), but rather, as you said earlier, the
space between the stopper and the glass or stopper and plastic is probably
the questionable barrier. Still, it's hard to imagine that 8 to 15 square
feet of plastic are not going to allow significant O2 to permiate. As a
datapoint, I brewed 15 gallons Ordinary Bitter in a 20 gallon HDPE container.
I added my own gasket to the lid so I think that wasn't as bad a source of
diffusion as it might have been. Well, when the time came to bottle, I was
busy and an extra three weeks went by with the batch sitting at 65F. It
had the most intense acetaldehyde aroma and flavor (even more than Bud) and
what with the rather mild flavor of an Ordinary, there was little to cover
it up. I don't suspect it was the yeast's fault, it was Wyeast 1028 or
1056. In any event, I'm convinced of the high O2-permiability of these
HDPE containers.
Al.
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Date: Fri, 22 Jul 94 13:54:19 EDT
From: zen at hophead.north.net (Nick Zentena)
Subject: Re: Lambic Digest #403 (July 22, 1994)
> Rick,
>
> I do not recommend that you add frozen fruit directly. I have had experience
> with this. Two years ago this very month, I added somewhere in the range
> of 8 lbs. of frozen cherries to an already primary fermented wheat ale.
> This frozen chunk of fruit dropped the temperature so low that the yeast
> went belly up. It was probably the yeast equivalent to the Titanic
> incident of years past (screaming, floating bodies, cherry flotsam, I go
> on). So please do not throw 6 months of your lambic life away on frozen fruit
There is no real problem with frozen fruit just thaw it out
first. The other thing is that freezing breaks the skin and lets
the yeast etc get going quicker.
Nick
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I drink Beer I don't collect cute bottles!
zen at hophead.north.net
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End of Lambic Digest
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