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HOMEBREW Digest #4491
HOMEBREW Digest #4491 Thu 04 March 2004
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
more bubbles and non-equilibrium dynamics ("Fredrik")
Freezer conversion. ("Darth Marley")
acetone in weizen (Marc Sedam)
Beer is a Cure for Cancer (Geoff Buschur)
Copper oxidation ("Ben Rodman")
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Date: Wed, 3 Mar 2004 07:53:21 +0100
From: "Fredrik" <carlsbergerensis at hotmail.com>
Subject: more bubbles and non-equilibrium dynamics
> Date: Tue, 2 Mar 2004 09:35:07 -0500
> From: "Dave Burley" <Dave_Burley at charter.net>
> Subject: Bubbles
>
Hello Dave!
Thanks for your follow up comments.
> Brewsters:
>
> /Fredrik published a site with some equations. Unfortunately, /Fredrik my
> same objection still holds.
>
> There is no "saturation equilibrium ratio of CO2 in the solution and the
> headspace", since the CO2 is SUPERsaturated, so K2/K3 ratio is undefined
and
> your equations fall apart as a result. As I have pointed out numerous
times,
> the CO2 in solution is NOT in equilibrium with the gaseous phase in normal
> time ( if you wait a few weeks or months then maybe, but you are in an
open
> system with your bubbler so the kinetics of this establishment of an
> equilibrium far out swamps all other considerations.
Dave, if you look at the equations you will see that they will indeed
predict the supersaturation level you are talking about. Supersaturation is
not magic, it is just a dynamical quasi equilibrium rather than a static
one. With saturation equilibirum ratio as I wrote, I meant this as a
reference. So these formulas does reduce to the equilibrium equations when
production = 0, and time -> infinity. Of course during production the liquid
is "supersaturated" which is also predicted by the model. I am assuming the
supersaturation level to be directly proportional to the local production.
As you know it is not enough to know only the ratio of kinetic constants,
you need to know both of them.
The higher the production of CO2, the higher the supersaturation and I
believe this to follow fairly accurate physical laws. Supersaturation is a
kind of dynamical quasi equilibrium, suppose you have a constant production
for some time, then there will be established a dynamical equilibrium wich
is of course different from the normal static equilibrium. And there will be
for the wort in question a well defined supersaturation. I agree the exact
level will be complex to find out, as junk acting as nucelation sites will
definitely affect the parameters k2 and k3 as the speed the release of CO2.
But this again is a problem of reality, not the model.
What I failed to explain is that, I do understand your point Dave, and yes,
the system is _not_ in equilibrium, I definitely understand this, but that
is why I have the differential equations. If everything was at equilibrium
there would be no need to use differential equations, then you could just
use the normal much simpler equations for equilibrium ratios. Non
equilibrium systems, even supersaturated solutions does follow the laws of
nature. Of course at equiblirium things are alot easier, but even at non
equilibrium it's doable. After all it's nothing but first order ordinary
differential equations. The equations can fill out my screen if they want to
(and they certainly will), but you can still just plug them in excel as easy
and get the dynamics simulated. That's why I love computers. This would have
been just plain undoable without a computer.
Does this make things more clear, guess not? :) I'm not sure if I am very
good at explaning :o| If it's still unclear give me time to finish this and
it will be evident if the approach works or not.
> Take my advice and run Clinitest in parallel with your experiment so you
will
> actually know the progress of the fermentation. Then compare this with
your
> bubble results.
Continously taking samples from the fermentor doesn't seem too practical to
me, this was one of the reasons I wanted an automated bubble logger. I would
like an automated sampler in that case which I figure would get horribly
expensive?
/Fredrik
>
> Keep on Brewin'
>
> Dave Burley
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Date: Wed, 3 Mar 2004 04:39:37 -0600
From: "Darth Marley" <darthmarley at comcast.net>
Subject: Freezer conversion.
Darth Marley's brewing buddy has purchased a chest freezer.
All brewing takes place at his apartment. And he has upgraded all my old
gear.
I encountered the designs for a wooden collar on the net. I like the idea,
but am having difficulty persuading him about the plan.
The previous plan was to drill through into the motor box. Does anyone have
info about if there are coils in that region of these units?
Has anyone converted a chest freezer by drilling through the walls?
Any thoughts on condensation leaking into the motor box? Or any other
reasons I can use to persuade my buddy to do it by building the collar
around the lid?
I feel like I know the best way to do it, but it isn't my money on the line
here. Please help me steer this project into the right direction.
------------------------------
Date: Wed, 03 Mar 2004 12:12:29 -0500
From: Marc Sedam <marc_sedam at unc.edu>
Subject: acetone in weizen
I brewed up 10 gallons of wheat beer about a month ago. 5 gallons went
right into a corny after primary fermentation and 5 stayed in my
MiniBrew fermenter for a few more weeks. Fermented with WhiteLabs
WLP380 (Hefeweizen IV).
The remaining 5 gallons has taken on a distinctive acetone odor. I
added an additional gallon of 1.040 "specialty malt wort" comprised of
Special B and 90L crystal to create a dunkleweizen. The acetone odor
seems to have dissipated a little but it's still there.
Any thoughts on why this might be? What kind of spoilage bacteria might
create this? I've drunk several pints of the kegged wheat with no ill
effects.
As for the yeast, seems better suited for the production of witbiers
than wheat beers. It's more flocculent than the standard Weinstephan
(WLP300, Wyeast 3068). I've never used the WLP380 before and wonder if
this is from the yeast and if it may fade over time.
Cheers!
marc
- --
Marc Sedam
Chapel Hill, NC
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Date: Wed, 3 Mar 2004 12:45:07 -0500 (GMT-05:00)
From: Geoff Buschur <gbuschur at mindspring.com>
Subject: Beer is a Cure for Cancer
http://www.40oz-warriors.com/news/?news_id=1199
I am invincible!!!! - OUCH! - Homer Simpson
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Date: Wed, 3 Mar 2004 15:22:48 -0700
From: "Ben Rodman" <brew-cat at earthlink.net>
Subject: Copper oxidation
Calling all metal geeks!
I recently received a CFC from B3, and the interior of the beer (inner)
tubing had a black, powdery-mildew-looking deposit on it as far down as I
could see. It didn't respond to scrubbing with an airlock brush (I know I
couldn't have scrubbed the whole thing, just tried it to see) and PBW
didn't touch it. A little research pointed to oxidation as being a likely
culprit, and a call to B3's welding guy confirmed it. Likely from the
brazing process, he said, glad to exchange it for you. Cool, but I just got
the new one and it's worse than the first! This one's solid black on the
inside.
Is there anything to do with apparently oxidized copper? Is this
oxidation, and is it a problem? I hate to just use it as is... I'm pretty
conscientious with equipment and not being able to see the interior I'd
like it as good as it can get when it's new, relying on attentive
maintenance to keep it in good shape.
Ben in Lyons, CO
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End of HOMEBREW Digest #4491, 03/04/04
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