HOMEBREW Digest #4843 Fri 09 September 2005

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  re: Contamination Follow-Up (SteveA)
  Acetobacter (Signalbox Brewery)
  Cooling Erlenmeyers (David Edge)
  esters (SteveA)
  Re: Erlenmeyer Flasks (Fred Johnson)
  more esters and then Aceto (Nathaniel Lansing)
  Re: Thomas Jefferson and Miller (Jeff Renner)
  RE: Erlenmeyer Flasks - FAQ help please! (Bill Adams)
  Re: Contamination Follow-Up (Jeff Renner)
  XL Smack packs are not big enough for mead ("Ted Manahan")
  Pedio erradication? ("Pat Babcock")
  Ester formation ("John Palmer")
  RE: Katrina - From Ron La Borde (Ronald La Borde)

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---------------------------------------------------------------------- Date: Fri, 09 Sep 2005 02:35:30 -0400 From: SteveA <-s at adelphia.net> Subject: re: Contamination Follow-Up Jeff Tonole wrote that, << Which brings me to a follow-up question -- assuming that the acetobacter has not yet affected the flavor of the beer in any significant way (which may be true of one or two batches), is there a way to kill off the bacteria and salvage the beer? />> There are antibiotic treatments, and of course pasteurization, but these are generally impractical. Acetobecteria are aerobic and so removing all O2 will stop the conversion of ethanol to acetic acid. I'd suggest you re-ferment with an ~10% starter of good yeast and immediately bottle-condition/keg-condition the result. -S Return to table of contents
Date: Fri, 09 Sep 2005 07:43:34 +0100 From: Signalbox Brewery <signalbox.brewery at ntlworld.com> Subject: Acetobacter Jeff asks if he can do anything to rescue his brew >Which brings me to a follow-up question -- assuming that the acetobacter has not yet affected the flavor of the beer in any significant way (which may be true of one or two batches), is there a way to kill off the bacteria and salvage the beer? Kill off I doubt, but acetobacter requires air and time so if they are drinkable (hmmmm) keg them, get CO2 in there and drink asap. If you do this let us know how you get on. David Edge Return to table of contents
Date: Fri, 09 Sep 2005 07:51:25 +0100 From: David Edge <david.j.edge at ntlworld.com> Subject: Cooling Erlenmeyers Rowan asks about cooling Erlenmeyer flasks. I'd like to know too, as I always start cooling them in warm water, but I would like to comment on: >or even better, sit the flask on a shelf in >the nearby freezer You'll get better heat transfer into water than on a freezer shelf unless perhaps the shelf is solid with ice. If you're in a hurry, wiggle it about (the flask). David Edge Return to table of contents
Date: Fri, 09 Sep 2005 06:29:15 -0400 From: SteveA <-s at adelphia.net> Subject: esters Matt asks the perennial question, what of esters. << I asked if they could explain the condtradictory statements that "increased yeast growth leads to decreased esters" (because Acetyl-CoA is being used for growth and not ester production) and "increased yeast growth leads to increased esters" />> The reason for the contradiction is that someone forgot Einstein's dictum, "make everything as simple as possible, but not simpler". This thought on ester formation was oversimplified into pablum. The short answer is that absolutist statements like "ester production is directly/inversely related to growth" are are almost pure baloney, which is to say these are both true under unstated conditions. There are several proposed paths to esters in beer, but the one with the preponderance of evidence is the reaction of an alcohol (ethanol or fusel) and a fatty acyl-CoA ester. Two enzymes are involved in the conversion .. an acyl CoA synthetase step which requires energy and an alcohol acyl-transferase step Acetyl-CoA is derived from pyruvate and acetate derived from the superabundant acetaldehyde (ethanol's precursor). It is also derived from amino acid catabolism. The AcetyCoA has several fates - but primarily it is used to produce fatty acids and sterols and the sterol precursor squalene. Yeast contain a lot of these fatty acids & sterols, and precursors, and this uses a vast amount of acetylCoA. The interesting point is this - it's been known for a quarter century that the ester synthesis rate increases about 4X at the same time the fatty acid synthesis ceases. It seems that the abundance of acetylCoA regulates the rate of ester production. Also there is some evidence that the presence of fatty acids (think trub) inhibits ester formation. Also experiments show that high levels of wort amino nitrogen lead to higher ester levels, presumably because the acylCoA produced from the aminos. We are stepping on very soggy ground here to say something so simple as, "things which *promote yeast growth* reduce final ester levels". This requires a definition of the conditions so here goes. When I say "promote yeast growth" I mean **avoiding the inhibition of fatty acid synthesis**. Let's be even more specific - fatty acid synthesis requires little more than glucose, a long list of enzymes and a few molecules of co-enzymes and some odd ions. In anything like wort the only possible means of stopping fatty acid synthesis *directly* is shutting down the sugar supply but this also stops the glucose->pyruvate->acetylCoA path at the very same time, so no acetylCoA and therefore no excessive esters when the sugar runs out. There are a million ways to inhibit fatty acid synthesis *indirectly* and these are the ester producers. Any growth limiting factor, other than lack of sugars, will usually cause yeast to suppress fatty acid synthesis and then *if* sugars or amino acids energy is still available, acetylCoA will be produced and create conditions for ester production. For example if you under-oxygenate your yeast or underpitch, then they will cease to grow when the sterol and UFA levels fall to critical levels. Their genetic machinery senses the condition and stops producing fatty acids needed for growth. If sugar is available, acylCoA pools and is available for ester synthesis. You can remove some enzyme co-factors or critical vitamins like biotin or pantothenic acid or remove the amino acids - and any of these will stop growth and permit increased ester formation. Any sort of "stuck" fermentation is ester territory. To re-iterate ... ester levels rise when there is sugar or excess aminos left and the yeast are alive, yet prevented from *growing* by some limiting factor. << Was this question indeed answered? Is is even possible to answer definitively? Is it possible to answer definitively if we only consider acetate esters? Is is possible to answer definitively if we only consider ethyl acetate? Anyone? />> Yes, it's pretty clear how it works, but I can't boil it down to a 1 sentence quip without oversimplifying. The several paragraphs above address the relationship between the fatty-CoA=>acetylCoA and esters. There are two pieces missing, the alcohols and the enzymes. One key factor in the ester profile of a particular yeast is it's particular set of alcohol-acyl-transferase enzymes are specific to the individual fusels. The reason some ale yeasts have a characteristic banana aroma while others smell of apples or other fruit is that these yeast produce different alcohol-acyl-transferase enzymes which are specific to the particular higher alcohols which are then esterified. There is some relationship between the levels of the alcohols (ethanol and fusels) and the amount of esters, BUT the alcohol acyl-transferase enzyme activity and the amount of acylCoA are usually the rate determining factors. For example Dave Burley is right; though temperature increases the amount of precursors fusels, the primary impact of high temp on ester formation has to do with increased activity of alcohol-acyl-transferase enzymes. To summarize, the yeast genetics control (in relative quantity at least) which esters will be produced by means of (fusel)alcohol specific acyl-transferases. The yeast produce these esters to a very limited extent in relation to the abundance of the fusel precursor, but primarily in relation to the acylCoA pool concentration. One means of creating a high acylCoA concentration is to give yeast abundant energy in the form of sugars or amino acids *but* to prevent then from using the acylCoA for fat by limiting some other growth factor. <<If ethanol is never the limiting factor, then my uneducated guess is that ester production is at any moment proportional to growth rate, with perhaps a spike when growth stops. But then the only reason we'd have more total ethyl acetate production at higher temps is if the rate of reaction were increased or something. And I don't think I buy that. />> Ethanol is never the limiting factor, yeast may make roughly 10-20ppm of ethyl-acetate from say 50000ppm(~5%) of ethanol, while also making 1ppm of isoamyl-acetate from perhaps 50ppm of the related methyl-butanol fusel. The butanol acyl-transferase in wort has perhaps 100 times the activity as the ethanol acyl-transferase. The reason the ethyl-acetate level increases with temp is the increased activity of the ethanol acyl-transferase enzyme with temp *and* perhaps that yeast membranes which normally segregate ethanol from this (largely mitochondrial) enzyme become more leaky and permeable at higher temps. -S Return to table of contents
Date: Fri, 9 Sep 2005 07:09:27 -0400 From: Fred Johnson <FLJohnson at portbridge.com> Subject: Re: Erlenmeyer Flasks Rowan asks about cooling hot Erlenmeyer flasks. Taking a piece Pyrex or Kimax glassware directly from a burner into ice cold water is inviting disaster. Simply let the flask cool on the counter top--use a trivet or hot pad--for a few minutes. It should be cool enough then to transfer it to an ice bath. If you aren't in a big hurry, let is sit at room temperature longer to be safe. (You soon learn these things the hard way when you are using a $300 piece of hand blown glassware.) Fred L Johnson Apex, North Carolina, USA Return to table of contents
Date: Fri, 9 Sep 2005 09:13:53 -0400 From: Nathaniel Lansing <delbrew at compuserve.com> Subject: more esters and then Aceto First for Jeff's question, >>-- assuming that the acetobacter has not yet affected the flavor of the beer in any significant way (which may be true of one or two batches), is there a way to kill off the bacteria and salvage the beer?<< Eliminate the air and the acetobacter can not grow, they are aerobic and you can suffocate them. ====== Dave, the clove/banana example may have not been the best because cloviness is a phenol and is less temperature dependent than the banana ester; but I get what you mean. I had pointed that varying levels from different esters in my original post. What tweaked me is that Dr. Cone is stating the opposite of what we've been thinking; that increasing biomass = decreased esters. So that repitching a large yeast cake should produce more esters, and pitching a smaller cake would create less esters. This goes against my personal experience. It think I going to revert to one of my old brewing rules and do what works for me in my brewery. Anyway I _like_screaming esters and puking levels of diacetyl. Ringwood yeast, gotta love it. Return to table of contents
Date: Fri, 9 Sep 2005 09:29:04 -0400 From: Jeff Renner <jsrenner at umich.edu> Subject: Re: Thomas Jefferson and Miller "Dave Larsen" <hunahpumonkey at hotmail.com> wrote: > I was doing some reading about Thomas Jefferson and his brewing > adventures: > > http://www.monticello.org/reports/life/beer.html > > They mentioned that he had a brewing buddy named Joseph Miller. > That got me > wondering: Was Joseph Miller one of the Millers, as in Miller Brewing > Company? Do anybody know? It seems highly unlikely. Miller is a very common name, I don't think there is any reason to think it's the same family. The article says that Joseph Miller had a daughter and a son. His son is described as "a successful inventor and engineer." He eventually settled in Virginia, and the article says that his descendants still live there. So the brewing line would have stopped with Miller, Sr. According to the 1903 history of US brewing, _One Hundred Years of Brewing_, Frederick Miller bought the Plank Road Brewery in Milwaukee in 1955 from Charles Best. It doesn't say where Miller came from. But the main reason for my post is to say that one of the books mentioned in the article, Michael Combrune's pioneering 1762 _Theory and Practice of brewing_, is available in reprint from Raudins Publishing http://raudins.com/BrewBooks/default.htm. Glenn Raudins, the publisher, is a HBDer, and has reprinted this and other rare, long out of print books on brewing and distilling, in beautiful bonded leather bound limited editions on heavy, acid free paper. They are printed in the (more or less) original fonts with original illustrations. As Glenn has explained it to me, he scans the original books into character recognition software, then painstakingly goes over the entire manuscript letter by letter to make corrections, insert the original illustrations, and set up the pages as original. They are printed in the original sizes, which are non-standard. In other words, they are virtually duplicates of the originals, but probably better. If you are interested in historic brewing, you'll want to take a look at these books. Jeff - --- Jeff Renner in Ann Arbor, Michigan USA, jsrennerATumichDOTedu "One never knows, do one?" Fats Waller, American Musician, 1904-1943 Calculate your Rennerian Coordinates at http://hbd.org/ rennerian_table.shtml Return to table of contents
Date: Fri, 9 Sep 2005 06:31:14 -0700 (PDT) From: Bill Adams <badams1010 at yahoo.com> Subject: RE: Erlenmeyer Flasks - FAQ help please! Here is what one company claims their containers will withstand: http://www.indigo.com/glass/gphglass/beaker-solder.html BA Return to table of contents
Date: Fri, 9 Sep 2005 09:36:53 -0400 From: Jeff Renner <jsrenner at umich.edu> Subject: Re: Contamination Follow-Up "Jeff Tonole" <jtonole at twcny.rr.com> wrote from Ithaca, NY: > assuming that the acetobacter has not yet affected the flavor of > the beer in any significant way (which may be true of one or two > batches), is there a way to kill off the bacteria and salvage the > beer? It shouldn't be necessary to do anything to kill the bacteria. It requires oxygen to live. Just rack the beer off, our out from under, the layer of acetobacter and bottle or keg it. If you keg it, make sure to purge the head space with CO2. Jeff - --- Jeff Renner in Ann Arbor, Michigan USA, jsrennerATumichDOTedu "One never knows, do one?" Fats Waller, American Musician, 1904-1943 Calculate your Rennerian Coordinates at http://hbd.org/ rennerian_table.shtml Return to table of contents
Date: Fri, 09 Sep 2005 09:01:23 -0600 From: "Ted Manahan" <ted_manahan at hotmail.com> Subject: XL Smack packs are not big enough for mead With the recent talk of the XL Smack Packs from Wyeast being pitchable, I was getting set up to try it. I just made a mead, and used the Wyeast sweet mead yeast. The package itself indicates that it is ready to pitch. So I did. However with an OG of >1.100, I may have been too optimistic. It's been two days now and no signs of fermentation. Rats. I'll give it another day. If nothing happens I'll re-aerate and pitch some dry ale yeast to get things going. Does anyone have any better ideas? Return to table of contents
Date: Fri, 9 Sep 2005 11:23:29 -0400 From: "Pat Babcock" <pbabcock at hbd.org> Subject: Pedio erradication? Greetings, Beerlings! Take me to your lager... With the coming of fall, a young mans fancy turns to... Brewing! Yes, after a hiatus of nearly five years, I'm contmplating firing my brew kettles once more. However, in some "beers" that were left on my draught system, I note the distinctive flavor of our friend pediococcus. Not wanting everything I put on draught to become a Belgian ale, I ask by what manner of sorcery can I rid my lines, fittings, faucets, and cold plate of these beasties? Would a NaOH soak for some amount of time suffice? If so, at what concentration and for how long? Since I regularly soaked the works in iodophor, I'm not certain that the answer lies therein. Of course, I'm assuming that the infection came from within the system - a fair bet, though, since it didn't start until after I put an Orval clone online years ago... -p Return to table of contents
Date: Fri, 9 Sep 2005 10:07:19 -0700 From: "John Palmer" <jjpalmer at altrionet.com> Subject: Ester formation Hi All, I am working hard on getting my book updated for publication by BP next spring, and I have had several discussions with Wyeast and Lallemand about ester formation. A current theory is that the enzyme AAT or Alcohol Acetyl Transferase is produced in the cell membrane during cellular reproduction. The more cell growth (ie. percent increase in cell count), the more AAT is created. Acetyl CoA is the predominant fatty acid in the wort, and generates the most esters. So, while Acetyl CoA can be utilized by the cell *for* growth, and thereby pre-empt ester formation, the resulting increase in AAT will mean that *more* esters will be formed after the growth phase, and this is consistent with observation that low pitching rates with worts that are well aerated for good growth have more esters than fermentations with high pitching rates, such as those made from 2 cups of slurry yeast from a prior fermentation. This is my understanding of it in a nutshell at the moment. John Palmer john at howtobrew.com www.realbeer.com/jjpalmer www.howtobrew.com - the free online book of homebrewing Return to table of contents
Date: Fri, 9 Sep 2005 11:34:04 -0700 (PDT) From: Ronald La Borde <pivoron at yahoo.com> Subject: RE: Katrina - From Ron La Borde >From: Bob Wilcox <bobw at budget.net> > >Has anyone heard anything from Ron LaBorde. From his >posts I know he is >from Metairie, La > >Bob Wilcox Yes, I am alright. Gail and I left to Texarkana (closest room available from Metairie!) two days before the hurricane. Thank all of you for asking, I am touched. We are in Baton Rouge area now and in the proccess of buying a second house for shelter purposes. I have inspected our house, only minor damage, the brewery is intact! We have two homebrew clubs in our area, and as far as I know at this time everyone has survived. Some lost just about everything. I have learned some lessons through life: * never buy a house with a street name like "Valley, or Lake", etc. * try to have a street address with heights or hills in the name. Cheers, Ron La Borde 3329 Metairie HEIGHTS Ave Metairie, La New Orleans is now New Atlantis! Ron Ronald J. La Borde -- Metairie, LA New Orleans is the suburb of Metairie, LA www.hbd.org/rlaborde Return to table of contents
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