HOMEBREW Digest #4491 Thu 04 March 2004

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  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 Return to table of contents
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. Return to table of contents
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 Return to table of contents
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 Return to table of contents
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 Return to table of contents
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