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


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Contents:
  RE: metallic flavor in first keg beer ("Peter A. Ensminger")
  Re: Yeast and oxygen ("Fredrik")
  Re: Metallic Taste In Corny Keg (Dan Jeska)
  RE: softened water in brewing ("Martin Brungard")
  Hop Isomerization ("Martin Brungard")
  Delirium Tremens (goetzr1)
  Re: metallic flavor in first keg beer (Derek Sheehan)
  secondary fermentation (Rick Weber)
  rice hulls and oak ("D. Clark")
  metallic taste in reconditioned keg (Aaron Martin Linder)


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Date: Sat, 11 Feb 2006 00:20:33 -0500
From: "Peter A. Ensminger" <ensmingr at twcny.rr.com>
Subject: RE: metallic flavor in first keg beer

Hi Aaron,

I have been using corny kegs for many years and have employed the "high
pressure/shaking method" and the "sit and wait method". My beer is never
perfect, but I have never detected a metallic flavor. BTW, I am a Beer
Judge, so I've tasted lots of weird stuff over the years.

First thing that comes to mind is that your beer is oxidized. This can
manifest as a metallic flavor. But I would be surprised if this develops
over a mere 2-3 days.

Another possibility is that your cleaning/sanitizing routine is to
blame. I typically use PBW, an alkaline cleaner, followed by StarSan, an 
acid sanitizer (NAYYY). This is not the cheapest way to prep your kegs, 
but it has never failed me.

Cheerio!
Peter A. Ensminger
Syracuse, NY
Beer data: hbd.org/ensmingr
Apparent Rennerian: [394, 79.9]




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Date: Sat, 11 Feb 2006 11:43:19 +0100
From: "Fredrik" <carlsbergerensis at hotmail.com>
Subject: Re: Yeast and oxygen

> Date: Fri, 10 Feb 2006 14:49:59 -0800
> From: "Peed, John" <jpeed at elotouch.com>
> Subject: Yeast and oxygen
> 
> 
> OK, I never did quite get the scoop on yeast oxygenation.  All the fuss
> with oxygenation seems to center around pre-fermentation oxygenation to
> build the cell walls.  But that begs the question: Why does stirring on
> a stir plate for the duration of starter fermentation make a starter
> ferment so much more rapidly and build more yeast?  Also, if you pitch
> the whole thing after stirring for a day, do you risk oxidation?  My
> experience says no.  Why not?
> 
> John Peed
> Oak Ridge, TN

FWIW, the way I understand it...

Stirring or shaking a container with headspace oxygen, speeds the 
uptake of oxygen from the headspace, as well as stimulating the culture,
and possibly reducing the level of CO2 supersaturation.

I read a paper (don't remember the reference from the top of my head, 
but if someone wants please ask and I might search for it) where it was 
confimed that in a stirred fermentation (brewers don't normally do this),
 the amount of headspace significantly affected the isoamylacetate level
 formed, and the difference was not marginal, it was a factor x5 between 
extrems if I remember correct, presumably because stirring in a air
 atmosphere amounts to a kind of later aeration. There was no oxygen 
injection, the "aeration" was only regulated by menas of the fermentor 
headspace, nothing else. And of course there was stirring in both cases.

Also, better cellemembranes gives higher fermentation performance and
 higher biomassyield. Of course if the headspace is infinite like stirring 
an open ferment without lid, when the glucose repression ceases 
maybe one might see some elevated degree of respiration. But I think 
this is not normal procedures.

The initial aeration builds the initial quality of the membranes, but as 
soon as the anaerobic reproduction sets in, the cellmembranes are 
deprived of UFA's and sterol because the mother shares with the daughter 
cells. This is the simple reason why yeast don't reproduce more than 
maybe the order of 5 generations anaerobicayll - at that point the quality 
of the cellmembrane is simply unacceptable. Of the exact point of 
unacceptable would depend also on simulatenous stresses. Combine that
sterol/UFA depletion with strong alcohol and osmotic stress  and I'm 
sure it will poop out earlier. Somehow the total accumulated 
stress on the yeast has an impact. All else beeing perfect, yeast can 
withstand much higher ethanol than if it's put to a range of simultaneous
stress.

About the significance of flavour due to various oxidation I don't have 
much comments at this point. My limited experience is that when you 
aerate the culture with high ethanol I tend to quite quickly feel elevated
 ethanol oxidations, because ethanol + oxygen, and without glucose 
repression might reverse things and yeast might try to respire on the 
ethanol.

I recall reading another paper some year/s ago where it was found that
 yeast has some not identifies pathways for dissipation of oxygen,
 that aren't related to respiration nor UFA/sterol synthesis.

I still don't have a clear picture on this, maybe Steve or someone else 
can fill in. I am currently working on my understanding here. 

 /Fredrik



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Date: Sat, 11 Feb 2006 08:32:42 -0500
From: Dan Jeska <dan.jeska at gmail.com>
Subject: Re: Metallic Taste In Corny Keg

Aaron Linder reports a metallic taste in a reconditioned corny keg he
just purchased. Aaron, I would completely disassemble any corny keg,
whether reconditioned or not, fill the keg and soak all the parts in a
PBW solution before putting it into service. Perhaps apply a brush to
the dip tube, poppets and posts. My experience with PBW is "it gets
rid of everything that doesn't belong there".

Dan
Brewing at (85.5, 277.7) Rennerian



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Date: Sat, 11 Feb 2006 07:02:05 -0900
From: "Martin Brungard" <mabrungard at hotmail.com>
Subject: RE: softened water in brewing

I liked Steve Alexander's question in the form of a major treatise on 
chemistry.  AJ's response to Steve's question regarding the use of 
ion-exchanged softened water in brewing was also very complete.

I echo AJ's comment about using softened water.  Why use a water that could 
have a potentially detrimental taste impact when the naturally hard water is 
generally better for brewing and doesn't have a negative taste impact.

Steve pointed out correctly that he replaces calcium ions with sodium at a 
rate of 1 to 1.15 (Ca to Na).  We need to remember that ion-exchange 
softeners also replace magnesium at a rate of 1 to 1.89 (Mg to Na).

Most drinking waters tend to have substantially more Ca than Mg, so the 
higher Mg replacement rate with sodium is less of an impact.  But, the 
combined impact of replacement can be significant depending upon the 
starting hardness of the base water.

To put the effect into prospective, lets assume that people would want to 
use a softened water when their water hardness is greater than about 120 ppm 
as CaCO3.  For that water, ion-exchange softening will drop the hardness 
substantially and increase the sodium content by about 40 ppm.  Forty ppm of 
sodium is definitely a flavor impact, and that's just for a moderately hard 
water.  It only gets worse for harder waters.

Steve is right, there are plenty of beer styles that would not have a 
detrimental result with 40 to 60 ppm sodium, but there are plenty of other 
styles that wouldn't be so successful.  Steve is right, a blanket statement 
that ion-exchange softened water can't be used in brewing shouldn't be made. 
  But the cautions that I make in this post should also be heeded and most 
brewers would make better beer with hard water instead of ion-exchanged 
softened water.


Martin Brungard
Tallahassee, FL




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Date: Sat, 11 Feb 2006 08:35:07 -0900
From: "Martin Brungard" <mabrungard at hotmail.com>
Subject: Hop Isomerization 


John Peed recently posted an item regarding hop isomerization that should be 
expanded upon.

John mentioned that hop isomerization was dependent upon mechanical mixing 
and heat, as in a good rolling boil.  Unfortunately, this is a brewing 
momily that is both true and false on several levels.

Let's first explore the need for mechanical mixing.  Mechanical mixing via a 
rolling boil is not always needed.  This is dependent upon the form of the 
hops used in brewing.  Pelletized hops have been in use for several decades 
now.  A rolling boil is not needed when pelletized hops are used.

There are several reasons why pelletized hops don't need the rolling boil.  
The first reason has to do with the methodology used to assess the alpha 
acid content of all hop products.  The ASBC and EBC methodologies both 
require that whole hops be fully mascerated (ground up) prior to testing.  
This is because the lupulin glands in the whole hops need to be ruptured to 
expose the lupulin.  Please note that this is the condition that pelletized 
hops are in.

Whole hops do require a rolling boil in order to help expose and burst the 
lupulin glands.   But the degree of the exposure and the degree to which the 
lupulin glands were burst during harvesting and packing will always be in 
question.  The degree of utilization of alpha acids is very much in question 
when using whole hops.

Brewers recognize that an increased utilization is applied when using 
pelletized hops.  Given the hop alpha acid testing methodology, its apparent 
that we should relate the utilization of whole hops as an under-utilization 
instead of relating an over-utilization for pelletized hops.

Recent research by Malowicki and Shellhammer confirms that alpha acid 
isomerization is soley dependent upon the wort temperature and time.  For 
boiling wort, the intensity of the boil doesn't change the wort temperature. 
  Therefore, its can be stated that the intensity of the boil does not 
affect isomerization when the alpha acid (lupulin) is fully exposed.

I hope this illustration helps brewers understand that a really active boil 
isn't really needed, except when using whole hops.

Martin Brungard
Tallahassee, FL




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Date: Sat, 11 Feb 2006 22:36:58 +0000
From: goetzr1 at comcast.net
Subject: Delirium Tremens 

Looking for a Delirium Tremens extract clone with steeping recipe. Thanks


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Date: Sun, 12 Feb 2006 08:34:52 -0500
From: Derek Sheehan <w7rex at comcast.net>
Subject: Re: metallic flavor in first keg beer

Aaron,

I started kegging a few years ago and have found it to be incredible. No 
more cleaning all those bottles!

As far as your metallic flavor, I have noticed that some re-conditioned 
kegs have lids with a little rust in the pressure relief valve assembly. 
At least the stuff I have found is dark like rust and has a very sharp 
metallic taste. I contribute this to the spring valve rusting somewhere. 
A dowel with a bit of green scrubby on the end gets the crud out and I 
replace the offending spring plunger.

Kegs have lots of cracks and spaces that are hard to clean and you have 
to be very vigilant to get them clean and sanitized.

We should get together sometime, brew and split a batch!

Derek in Dexter



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Date: Sun, 12 Feb 2006 12:28:41 -0600
From: Rick Weber <rick.weber05 at gmail.com>
Subject: secondary fermentation

Hey,

Two questions: First, I don't seem to get any change in specific
gravity after I rack my beer to the secondary fermentor; why? I
generally rack about 4 or five days after it goes into the primary,
when the krausen has fallen and the airlock burps about once every 10
seconds.

Second, my original gravities have been much higher than expected with
higher alcohol output than expected also. I just bottled a batch of a
brown ale (Theakston's Old Peculier) and got an alcohol output of 9.4%
compared to an expected 6.2% in Clone Brews, the original gravity was,
if I remember correctly, about 0.015 higher than expected.

Thanks for the help,
Cheers!
Rick

- --
"Education: The ability to listen to almost anything without losing
your temper or self confidence."
- -- Robert Frost



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Date: Sun, 12 Feb 2006 13:36:18 -0500
From: "D. Clark" <clark at capital.net>
Subject: rice hulls and oak

Hi list,

I brewed up a wheat beer Saturday using rice hulls for the first time.  I 
had a pound bag, so I tossed about half into my mash.  No problems mashing 
and the sparge went off without a hitch.  Thanks for the help.

With all the talk of oak barrels or adding oak chips or flakes to beer, it 
raises the question of what styles of beer would benefit from the oaky 
flavor.  I would think primarily ales and Belgian styles but also stouts 
and porters.  Oak chips are available everywhere for adding to wine, but if 
they were to be used in beer, when would you put them in?  Would they go 
into the boil, primary or in the secondary?  Just food for thought.

Back to water again.  I have sent samples of my very hard well water and 
some spring water to be tested.  I made the wheat beer with the spring 
water this time.  I preheat my sparge water on the woodstove in the name of 
efficiency, and it will generally boil for a while before I am ready to use 
it.  Usually there will be a big load of a tannish colored precipitate with 
my well water, but this time there wasn't a speck of anything floating 
around.  I think that will bode well for this beer.  I'll post the test 
results for comment when I get them.  Happy brewing.

Dave Clark
Eagle Bridge, New York
  



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Date: Sun, 12 Feb 2006 19:37:08 -0500 (EST)
From: Aaron Martin Linder <lindera at umich.edu>
Subject: metallic taste in reconditioned keg

Hi,

This is a followup post to point out the most likely source of a mild 
metallic flavor in my first kegged beer.  I originally purchased three 
reconditioned, acid-washed kegs from SABCO.  The first I rinsed thoroughly 
with water and used as is.  I inspected the second two today and found 
that I could smell a faint metallic odor coming from the empty keg.  So, I 
rubbed some tissue on the inside of the kegs, and sure enough there was a 
gray, very fine residue on the tissue!  ----!  I should have paid more 
attention the first time.  Anyway, I thoroughly scrubbed the two remaining 
kegs with detergent and rinsed them. they lost their metallic odor.  I 
guess this shows that one shouldn't be lazy or careless at least.

I don't know what the residue was. Perhaps a layer of metal oxide leached 
off of the keg after SABCO's processing.

aaron linder
Ann Arbor, MI





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