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


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Contents:
  photodecomposition of beer ("Peter A. Ensminger")
  Hops ("William Frazier")
  Source of Chlorophenols in my Beer? ("Eric R. Theiner")
  Using chest freezer with dorm fridge attached (Aaron Martin Linder)
  more esters, and also acids (Matt)


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JANITORs on duty: Pat Babcock (pbabcock at hbd dot org), Jason Henning,
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Date: Mon, 12 Sep 2005 00:00:49 -0400
From: "Peter A. Ensminger" <ensmingr at twcny.rr.com>
Subject: photodecomposition of beer

For all you beer geeks out there ...

A recent review article entitled: 'Shining Light on the
Photodecomposition of Beer' by Kevin Huvaere & Denis De Keukeleire
(Ghent University, Belgium) has been published in "The Spectrum". The 
full text is here:
www.bgsu.edu/departments/photochem/research/summer2005spectrum.pdf

This new review article discusses recent research on the mechanism of 
the flavin-mediated light-struck reaction, which leads to formation of 
'skunky' mercaptans following exposure of beer to blue light.

Cheerio!
Peter A. Ensminger
Syracuse, NY
http://hbd.org/ensmingr/



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Date: Mon, 12 Sep 2005 00:27:37 -0500
From: "William Frazier" <billfrazier at worldnet.att.net>
Subject: Hops

I've spotted some wild hops growing near my house.  When are hops ready to 
pick?  What are signs of hop flower maturity?  Thanks.

Bill Frazier
Olathe, Kansas USA 




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Date: Mon, 12 Sep 2005 9:01:53 -0500
From: "Eric R. Theiner" <rickdude at tds.net>
Subject: Source of Chlorophenols in my Beer?

Hey brewpeople,

I've got a chlorophenol problem that I'm trying to track
 down and I think I might have got it limited to one of 
two sources... and I think I know which one, but I'm 
going to put it to the group.

The first possibility is the water--

I'm in Madison, WI using the local water after it goes 
through my ion-exchange softener (strips out Mg & Ca and 
replaces with Na, then goes the other way with a brine 
regeneration).  The water here is pretty alkaline, so I 
pre-boiled with extra calcium added via calcium chloride 
to precipitate out a bit of the carbonate, and then 
blended in fresh water that had not been pre-boiled.

I still had to use a good bit of acid blend to get my 
mash pH right, though.

Anyway, I understand that the chlorine content in my 
water will hit a top end of 4-5 ppm, and this is through 
hypochlorite, not through chloramines.

The second potential source would be my drinking water 
grade hose--  I think.

I never had a "green hose" flavor from this hose before 
('cos it's white, after all).  But I ran some hot water 
through it here and there, and only later learned that 
you're not supposed to do that.  Recently, I ran some 
water through it and caught it in a glass and that water 
was vile!  Not infected or moldy or anything, but very 
"hosey."  Being as all of my brewing water moves through 
this hose, could that be the initial source of my 
chlorophenols?

Thoughts are appreciated!

Rick 




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Date: Mon, 12 Sep 2005 12:04:02 -0400 (EDT)
From: Aaron Martin Linder <lindera at umich.edu>
Subject: Using chest freezer with dorm fridge attached

Hi all,

I have a question about using an old chest freezer that I have.  The 
freezer does not work, the compressor runs, but it must have a freon leak, 
as it runs for awhile then shuts the compressor off.  Anyway, I have been 
told it is not worth fixing it.

So, I was wondering if anyone has any practical experience with connecting 
a dorm fridge or other cooling device to a chest freezer to use as a 
fermentation chamber?

I have an approximately 1.5-2 ft^3 dorm fridge.  I was thinking about 
cutting two 4 inch holes in the side of the chest freezer and inserting 
one/two duct fans (had them lying around anyway) blowing in opposite 
directions into and out of the chest freezer cavity as well as the dorm 
fridge, which would be sealed against the side of the chest freezer.

I would then connect the two duct fans and the refrigerator into a power 
strip that would connect into a temperature controller with its probe in 
the chest freezer.  This way I can use the insulating capacity of the 
chest freezer without throwing it out and also use my dorm fridge.

Do you have any advice on the design?  Is the dorm fridge going to be able 
to handle the task? I want to be able to at least go down to 60 degrees F 
for some ales or maybe hit 32 F for a lager now and again with my ambient 
basement being around 70-75 in the summer.  Would it be more efficient to 
just buy a used chest freezer or fridge and use that instead?

I also thought about just  putting a heating unit of some sort in the 
freezer and using it in my <= 20 degree F garage in the winter.  Would 
this be more efficient?

Thanks for any help you can offer.

Aaron

- --------------------------------------------
Aaron Linder
Research Laboratory Specialist Associate
The University of Michigan
School of Public Health I
109 S. Observatory, Rm. 3610
Ann Arbor, MI 48109
734-764-4399
lindera at umich.edu
- --------------------------------------------





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Date: Mon, 12 Sep 2005 10:05:03 -0700 (PDT)
From: Matt <baumssl27 at yahoo.com>
Subject: more esters, and also acids

Thanks to everyone who took the time to explain some things about ester
formation (and hose problems).

Among other things, Steve explains how "stuck ferments" (shortage of
some growth factor other than sugar causes yeast to stop growing) are
likely to lead to increased acetate esters in practice.  Unless the
production of Acetyl-CoA (primarily from sugar) is halted at the same
time that growth is halted, idle hands can make the Devil's work with
the large surplus of Acetyl-CoA.  Perhaps more the Duvel's than the
Devil's in some happy cases.

In the interesting theory reported by John Palmer, an increase in total
growth leads to the production of more AAT enzymes, thus to more esters
produced "after the growth phase."  It seems that this could even
provide an amplifying effect, in that acetate esters would be increased
more than proportionally to the total growth.  BUT, wouldn't any
post-growth-phase production of acetate esters have to utilize
acetyl-CoA that was produced before the sugar ran out, and now is just
hanging around in the yeast cells (or possibly the beer)?

Some points and questions:

1.  I think pitching rate affects total growth ONLY because of the
small amount of energy required for (non-growth-related) background
maintenance of the cells.  Posts (I recall some by Steve) in the
archives suggest that this is a pretty small amount of energy and hence
total growth should not change dramatically with pitching rate.  But if
there is a pool of Acetyl CoA laying around after growth stops, and AAT
enzymes were produced in proportion to growth, then depending on
reaction and denaturing rates, etc, small amounts if increased growth
could lead to disproportionately large increases of acetate esters.

2. IS there a pool of Acetyl CoA lying around after growth stops?

3. Do fatty acids ever leave the cell walls and if so what is their
fate?

4. More practically--can I increase the iso-amyl acetate in my beer,
without increasing (and in fact reducing) isoamyl alcohol levels, by
simply adding acetic acid to the wort?  I assume not, because how would
it get into the yeast cells and how would it get transformed to
Acetyl-CoA... but who knows?

Matt




		


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