HOMEBREW Digest #4437 Sat 27 December 2003

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  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 Return to table of contents
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 Return to table of contents
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 Return to table of contents
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 Return to table of contents
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