From the HBD Archive
From: Bob Devine 28-May-1992 0939 <devine@cookie.enet.dec.com>
Subject: yeast and copper
Date: 1992-05-28 15:45:48 GMT

Noel Damon asks:
> [...] the last batch was made in a new mash/lauter tun in which I used
> a 1" circular copper slotted tube as the filter element. This was its first
> use, and although I cleaned the copper well, when the mash was done, the
> tube was a much brighter uniform color than when I started. Is it possible
> that copper salts were generated which did a number on some of the yeasties,
> or am I left to conclude a yeast problem?

Hi Noel, the acidic nature of a mash will remove the oxydized layer
from the copper (kitchen hint: use ketchup to "clean" copper pans because
its acid will brighten them). The amount of copper ions removed should
be consumed by the yeast without a problem[*]. Many folks use the
slotted copper pipe system for lautering, so I suspect a yeast problem
(assuming that all cleaning used beer-safe chemicals).

Bob Devine
[*] While some copper is okay, too much can be damaging. Big commercial
breweries do use copper boil kettles but don't use copper pipes or
copper lager & holding tanks not only because of cost concerns but because
the first runnings through copper do have a much higher concentration so
that a more consistent "product" is obtained with stainless steel.

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