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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
  Re: Duhhh! (Kent Fletcher)
  Copper/NaOH Chemical Resistance (Fred Johnson)
  re :Tannin squeezins'/mad-cow sausages ("-S")
  How to make Melanoidin Malt (Grant Family)


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Date: Thu, 25 Dec 2003 23:47:46 -0800 (PST)
From: Kent Fletcher <fletcherhomebrew at yahoo.com>
Subject: Re: Duhhh!

> A.J. mistyped slightly in his response to the OP's
> question about inverting the output of a temperature
> controller:

And then after correcting A.J.'s typo (SPST, should
have been SPDT), I did the same thing myself when
saying that there is no need to switch the neutral
side of the circuit.Duhhh!

Kent Fletcher
Brewing in So Cal




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Date: Fri, 26 Dec 2003 16:21:23 -0500
From: Fred Johnson <FLJohnson at portbridge.com>
Subject: Copper/NaOH Chemical Resistance

Friends:

I was considering the cleaning method I will use with my new copper 
counterflow chiller and have always found sodium hydroxide as a 
reliable agent for cleaning. I was also considering storing the chiller 
filled with a solution of sodium hydroxide. (Nothing is going to live 
in that stuff between brews.)

I went to my trustworthy Cole-Parmer catalog to check out the chemical 
resistance chart located in the back, and I found the following listed 
as the resistance of copper to various concentrations of sodium 
hydroxide:

sodium hydroxide (20%) - no effect ( satisfactory to 120 degrees F)
sodium hydroxide (50%) - minor effect
sodium hydroxide (80%) - severe effect: not recommended

So I felt pretty comfortable making up a 5% (w/v) solution of sodium 
hydroxide and circulating this through the inner tubing coil. After 
about 30 minutes, the solution had turned a nice Carolina blue.

So what's the explanation?

I wonder if the blue color is the result of some salt, such as cupric 
oxide being dissolved by the solution leaving behind clean copper which 
will be essentially inert to the sodium hydroxide. Or is the 
Cole-Parmer catalog incorrect? Will a 5% sodium hydroxide solution 
corrode the copper?

Fred L Johnson
Apex, North Carolina, USA



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Date: Fri, 26 Dec 2003 19:28:06 -0500
From: "-S" <-s at adelphia.net>
Subject: re :Tannin squeezins'/mad-cow sausages

Pat B writes ...

>Scott Alfter wrote:
>
>> but squeezing the bag can pull out tannins and/or other
>> undesirable substances.
>
>Tannin extraction is a function of pH and not of mechanical
>pressure.

There is, as far as I know,  no [none, zero, nada]  demonstration of this
bit of HB lore that pH determines tannin extraction.  It may be true, but I
tend to doubt it.

Barley has no real tannins, tho' some polyphenolics which have been referred
to as tannoids are part of the category of polymeric flavanols.   These
flavanols are the troublemakers involved in haze, bitterness and astringency
(but typically only after oxidation & polymerization post boil) .  The other
below flavor threshold in beer, but may even contribute minor positive
flavor characteristics - except when carboxylated into off-flavored smokey,
medicinal, clovey off-flavored compounds.

Tannoid and tannoid precursors actually drop in concentration as the lauter
proceeds, but the concentration of total extract drops even faster !  This
means that late runnings have less tannoids, but the ratio of tannoids to
sugar is increasing.  Late runnings also have more protein, much more
silicates (harsh husky tasting) more mineral solute, more polysaccharides,
more starch and more phosphate compared to extract too.  Late runnings are
decidedly inferior in flavor quality to earlier runnings, but tannoids are
only one of many possible causes and not the most serious IMO.

What is known is that pH  and flavanols as a fraction of extract both rise
late in the lauter.  This is only correlation and causation has not been
demonstrated anywhere I've seen .... and  I've looked.

Mash-lauter pH rises as natural succinic acid  (a generic term for many
organic acids in plant matter) levels drop.  Flavanols are typically bound
in o-glucosyl arrangements in plant tissue.    These o-glucosyl bonds are
weaker at LOW (acidic) pH values.   The normal means used in scientific
studies for extracting flavanols and tannins for study is to use an
acidified solvent, 1% HCl in 70% acetone or 15% acetic acid in methanol for
example   Alkaline extraction is effective for the simple phenolic acids
which are most often bound by esteric bonds to plant tissue.

It seems unlikely to me that the minor pH shift late in the lauter (about
+0.5 pH by the time lauter gravity is down to 2P) can be responsible for any
dramatic change in tannoid extraction.   Most likely late runnings just
carry more of the goods away from the then rapidly degrading waterlogged
cells.   Silicate levels in late runnings are probably the biggest flavor
hazard.

>Squeeze away with no fear of causing tannin
>extraction.

True.   These squeezins will give a higher lipid content, but nothing to be
concerned about for a partial mash.

====

On an only vaguely brewing related topic ....

I was a little surprised to read recently that BSE can be carried in cow
intestinal tissue and it is assumed by some experts that the UK human
infections were generally caused by sausage casings !   "There are three
things that even God doesn't know: how a trial will end, what a woman is
thinking and what is in a wurst".

 -S




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Date: Sat, 27 Dec 2003 12:42:05 +1100
From: Grant Family <grants at netspace.net.au>
Subject: How to make Melanoidin Malt

G'day

Anyone got (specific) info on how Melanoidin Malt is made and how it
might be done at home? What malt should I start with - Pils, Vienna,
Munich...?

Cheers
Stuart Grant
Hobart, Tasmania, Australia



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