From the HBD Archive
From: Richard Hargan <HARGAN@UMDD.UMD.EDU>
Subject: Precipitate in wort.
Date: 1989-06-26 23:46:15 GMT

I recently brewed up a 3 gallon batch of wort which I plan to use as a
yeast starter for liquid yeasts. I used a can of John Bull Light Malt
Extract (hopped) dilluted to 3 gallons. I brought this to a boil in my
stainless steel stock pot and maintained a rolling boil for about a
half hour. I noticed that the wort darkened somewhat during this process,
but did not pay much attention to it. I transfer the hot wort to one
quart canning jars and placed them into a pressure cooker. I maintained
the pressure cooker at 10 psi for about 30 minutes. When I removed the
jars from the cooker, I noticed that the wort was VERY dark and a light,
fluffy precipitate had formed in the bottom of the jars.

My questions are,

- Why did the wort darken from an amber color to a dark color? Is this
normal? Personally, I prefer dark beers, but I am a little curious as
to why there should be such a pronounced change in color.

- What is the precipitate that has formed in the bottom of the jars? I had
placed a small amount of vivegar in the water in the bottom of the pressure
cooker to prevent water stains (or so the instruction manual advised),
and I suppose it is possible that some of the vinegar vapor could have made
it's way into the jars, but that seems a little unlikely to me. I had
originally planned on using an unhopped malt extract in this batch, but
after checking on my supplies, all I had was hopped extract. Could this
explain the precipitate?

I am going to go ahead an use one of the jars of wort as a starter for some
Wyeast and brew up a batch of Irish Ale and see what happens. I had planned
on getting a yeast bank kit and preserve some of the starter culture for later
use, but now I just want to see if the starter wort is contaminated.

If anyone has any suggestions/explainations for what happened, I would be
interested in hearing them. Thanks.

Richard B. Hargan
Systems Programmer

Room 1309 (301) 454-2946
Computer Science Center
University of Maryland
College Park, MD 20742-2411

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