HOMEBREW Digest #4625 Mon 11 October 2004


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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
  Reason for sugar residuals - (Energy/stress/biomassyield) ("Fredrik")
  Fortnight Of Yeast, 2004 - Published attenuation levels for various yeasts (Fred Johnson)
  Counterflow Issues (Grant Family)
  Curve Fitting ("Martin Brungard")
  Re: counterflow issues ("Spencer W. Thomas")
  Atteunation, yeast vs wort (correction) ("Fredrik")
  Pump Mounting ("Michael O'Donnell")

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---------------------------------------------------------------------- Date: Mon, 11 Oct 2004 07:47:37 +0200 From: "Fredrik" <carlsbergerensis at hotmail.com> Subject: Reason for sugar residuals - (Energy/stress/biomassyield) These are really interesting and head on questions! I think asking this to the fortnight experts is a great idea. Just to stir the pot for the moment and through out some more wild speculations... ..one working hypothesis that I intended to implement in the simulation(to see if it's consistent) is a kind of energy flow model where there has to be a positive balance, of energy production and expensses. Expenses are of course biosynthesis, active transport of nutritions into the cell, and transport of waste out of the cell. Also I suspect stressful conditions increases the expenses in several ways. To account for this, I think it would be unnatural for the equilibrium residuals to be zero. I mean, who of us licks the plate after a meal? A dog might say there is still plenty of food left on the plate. Ii's not wort the effort to lick the plate. The maltotriose is the last to do, should be because it happens to be the most expensive food to refine, and different strains have different affinity to it (due to variable expression?). I admit this is alot of theorizing and I may be wrong, but so far it looks promising, so if anyone can point to flaws in my reasoning before I take it too far. I would appreciate it. Anyway I suspect the first thing that happens is that the biomass drops, of course the yeast by definition continues to grow all the way until they go dormant, but as sugar concentrations drop and stresses from waste products and nutrition depletion increases the biomass yield drops. At some point, the biomass yield is so low that it is not favourable to "stay ative". The obvious suggestion to this treshold would be biomassyield roughly 0. However I am not sure, it's exactly 0? Any ideas? The biomass yield seems like a good choice of correlator to the energy stress level? That would suggest that when we see typical biomass yields of 5%, it might be alot higher in the beginning when nutritions are in excess and stress and production inhibition is low, and then drops. This is something that seems very consistent with the major boost in biomass yield you get using a stirrer - even if no O2 is introduced. It reduces stress and concentration gradients (which is also a kind of stress). The only sensible explanation to this I've found is that the biomass yields drop to basically zero during normal conditions, and the stress reduction io biomass yields is major, rather than just some % one way or the other. I think what needs to be done is to quantify this and put it all togehter and see what it gives. One question I intented to place to the fortnight is: Does the biomass yield basically drop to "close to zero" before dormancy? (this is what I would speculate) If not, how low does it typically drop? Perhaps some of you guys has any comments to this? that perhaps even could lead to spin off questions to ask the experts? /Fredrik Return to table of contents
Date: Mon, 11 Oct 2004 06:36:50 -0400 From: Fred Johnson <FLJohnson at portbridge.com> Subject: Fortnight Of Yeast, 2004 - Published attenuation levels for various yeasts Commercial yeast producers and others publish attenuation figures for each yeast. Are these figures obtained using a standard protocol within the company publishing the results? Are these figures obtained using a standard protocol across the industry? If so, how does that protocol relate to the vast array of wort compositions and fermentation conditions that are encountered in the commercial brewery and in the home brewery? I suspect that the reasons yeasts vary in the degree to which they attenuate wort are only partly known, but I would appreciate a brief summary of what is known about this. Fred L Johnson Apex, North Carolina, USA Return to table of contents
Date: Mon, 11 Oct 2004 23:32:33 +1100 From: Grant Family <grants at netspace.net.au> Subject: Counterflow Issues Hi all, Today I bought a coil (18m/50ft) of 1/2 inch OD copper and would like to build a counterflow chiller (CFC), but I'm not sure if my setup will allow it. Here are the potential problems as far as I can see: i) I don't have a pump and so would need to use gravity to feed the CFC. My boiler doesn't sit much more than a metre (3-3.5ft) off the ground and I'm unsure of whether I'll have troubles with gravity flow. ii) My boiler (a keg with the top cut out) doesn't yet have a tap. As such, I normally have to syphon the chilled wort (chilled with a borrowed immersion chiller) out over the top of the keg and into the fermenter. Will this make syphoning through a CFC too slow and/or prone to clogging? iii) I use only hop pellets and have no access to adequately fresh whole hops. Will this cause me untold grief in terms of trub in fermenter/loss of wort? Any advice, especially from people who had/have similar problems, would be appreciated. Thanks, Stuart Grant, Hobart, Tasmania, Australia. Return to table of contents
Date: Mon, 11 Oct 2004 05:12:22 -0800 From: "Martin Brungard" <mabrungard at hotmail.com> Subject: Curve Fitting Lately, there have been several comments on the difficulty of developing an equation for an existing data set (curve fitting). There are software packages out there that can make the job much easier. One of the most widely known packages is Excel. Another is Grapher. Both of these programs are commercial and somewhat expensive. Curve fitting is not their main purpose. Neither of these programs do this job very well. Fortunately, there is a cheap way to get a better solution. There is a shareware product called CurveExpert that is specifically intended for curve fitting. It does a very good job. The program includes a number of curve fitting solutions, making it more likely that you will come up with a better equation for your data set. For the limited work that most of us would likely use the program for, it is essentially freeware. You can download the program from the following link. http://curveexpert.webhop.biz/ For anyone dealing with developing equations for observed data, this is a great time saver. Martin Brungard Tallahassee, FL Return to table of contents
Date: Mon, 11 Oct 2004 10:40:27 -0400 From: "Spencer W. Thomas" <hbd-mod at spencerwthomas.com> Subject: Re: counterflow issues Stuart Grant asks: > i) I don't have a pump and so would need to use gravity to feed the CFC. My > boiler doesn't sit much more than a metre (3-3.5ft) off the ground and I'm > unsure of whether I'll have troubles with gravity flow. I've used gravity flow to pull wort through my CFC from a kettle sitting on the stove top. The stove top is about 1 meter from the floor. > > ii) My boiler (a keg with the top cut out) doesn't yet have a tap. As such, > I normally have to syphon the chilled wort (chilled with a borrowed > immersion chiller) out over the top of the keg and into the fermenter. Will > this make syphoning through a CFC too slow and/or prone to clogging? Again, I siphon from my kettle. I have a copper "racking cane" that reaches to the bottom "corner" of the kettle, and has a gentle bend at the top, so that the plastic hose doesn't kink. I did have to buy some silicone tubing, as regular "vinyl" tubing is not safe for boiling temperature wort. My vinyl tubing got very soft, and also I had problems with it introducing a plastic taste -- I had to dump 2 batches of beer. > > iii) I use only hop pellets and have no access to adequately fresh whole > hops. Will this cause me untold grief in terms of trub in fermenter/loss of > wort? I think that pellets may be easier to deal with than whole hops. Whole hops can easily plug the end of the racking cane, while pellet hops should get sucked in, instead. I whirlpool my wort at the end of the boil. The hops & trub settle out into a cone in the center of the kettle, and by siphoning from the edge, they interfere very little with the siphon. I also enclose the end of the racking cane in a copper "scrubbie" to help filter out those hops that do "wander" in that direction. You can see a picture of this in action at http://homeroastnbrew.info/homebrew/chilling/ =Spencer Return to table of contents
Date: Mon, 11 Oct 2004 18:31:01 +0200 From: "Fredrik" <carlsbergerensis at hotmail.com> Subject: Atteunation, yeast vs wort (correction) Thanks Fred Johnson for pointing out there a typo in me previous post. I post this correction of my previous post now to avoid further confusion for anyone else who might read this. In the definition of RDFW it should obviously be: RDFW = Real Degree of Fermentabilit of Wort (=glucose+fructose+sucrose+maltose +MALTOTRIOSE; % of extract) the maltotriose term was missing in my last mail, sorry. (Where maltotriose = MTW) RDFW = is supposed to be the maximum potential degree of fermentability. /Fredrik Return to table of contents
Date: Mon, 11 Oct 2004 10:56:16 -0700 From: "Michael O'Donnell" <mooseo at stanford.edu> Subject: Pump Mounting Hi all, Probably a dumb question, but how important is it to mount a centrifugal pump in a horizontal position? I notice that March recommends it, and most brewery pictures I see have them mounted that way, but I was just wondering what the considerations are? Is it a fluids issue, or worry about wear on the bearings? cheers, mike Monterey, CA Return to table of contents
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