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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
		Digest Janitor: pbabcock at hbd.org


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Contents:
  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





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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



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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



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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





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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



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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.



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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




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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


	
		


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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




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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?




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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



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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




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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



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