From the HBD Archive
From: <D_KRUS%UNHH.BITNET@mitvma.mit.edu>
Subject: RE: John Polstra's comments on aluminum kettles
Date: 1990-05-03 16:05:00 GMT

Distribution-File:
homebrew%hpfcmr@hplabs.hp.com

To all:

John Polstra's comments on aluminum kettles was right on the
money. To look at this qualitatively, the pH of tomato juice is ca. 4.
Now, lets make spaghetti sauce. Add all of your spices and boil (simmer)
for a while. The pH is going to be less than 4 (i.e., more acidic).
According to Papazian, mashing enzymes work best around a pH of 5.4.
Even after boiling for an hour the pH isn't going to change munch. So already
I have presented a pH difference relative to time of exposure to the "acid"
(pH of 4 vs ca. 5.4 with respect to days of exposure to hours exposure,
respectively). Even after years of making spaghetti sauce in the same
aluminum pot, one does not see pitting therefore one should not see pitting
after years of boiling wort. For your beer to have a noticeably matallic
flavor you would have to actually see significant pitting of the pot since
pot pitting is indicative of the act of dissolving the pot.

Just another point: I work with trace metals in environmental samples and
when I want to keep metals in solution I have to use extremely harsh pH's
(ca. -2 to +3). This means keeping the metals dissolved.

When I get the time I will do an Atomic Absorption Spectrometric workup
for the presence of aluminum in the wort due to being boiled in an aluminum
kettle.

Dan

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