FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
Digest Janitor: pbabcock at hbd.org
***************************************************************
OCTOBER'S HOME BREW DIGEST BROUGHT TO YOU BY:
Ypsilanti Brewing Company
Visit them at http://www.ypsilantibrewing.com/
Support those who support you! Visit our sponsor's site!
********** Also visit http://hbd.org/hbdsponsors.html *********
DONATE to the Home Brew Digest. Home Brew Digest, Inc. is a
501(c)3 not-for-profit organization under IRS rules (see the
FAQ at http://hbd.org for details of this status). Donations
can be made by check to Home Brew Digest mailed to:
HBD Server Fund
PO Box 871309
Canton Township, MI 48187-6309
or by paypal to address serverfund@hbd.org. DONATIONS of $250
or more will be provided with receipts. SPONSORSHIPS of any
amount are considered paid advertisement, and may be deductible
under IRS rules as a business expense. Please consult with your
tax professional, then see http://hbd.org for available
sponsorship opportunities.
***************************************************************
Contents:
pH and temperature ("A.J deLange")
Brix and Plato ("A.J deLange")
Re: Mash Temp and Color (Kai Troester)
acid bath for wort chiller? (Jon Fischer)
* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* The HBD Logo Store is now open! *
* http://www.hbd.org/store.html *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Beer is our obsession and we're late for therapy! *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Send articles for __publication_only__ to post@hbd.org
If your e-mail account is being deleted, please unsubscribe first!!
To SUBSCRIBE or UNSUBSCRIBE send an e-mail message with the word
"subscribe" or "unsubscribe" to request@hbd.org FROM THE E-MAIL
ACCOUNT YOU WISH TO HAVE SUBSCRIBED OR UNSUBSCRIBED!!!**
IF YOU HAVE SPAM-PROOFED your e-mail address, you cannot subscribe to
the digest as we cannot reach you. We will not correct your address
for the automation - that's your job.
HAVING TROUBLE posting, subscribing or unsusubscribing? See the HBD FAQ at
http://hbd.org.
LOOKING TO BUY OR SELL USED EQUIPMENT? Please do not post about it here. Go
instead to http://homebrewfleamarket.com and post a free ad there.
The HBD is a copyrighted document. The compilation is copyright
HBD.ORG. Individual postings are copyright by their authors. ASK
before reproducing and you'll rarely have trouble. Digest content
cannot be reproduced by any means for sale or profit.
More information is available by sending the word "info" to
req@hbd.org or read the HBD FAQ at http://hbd.org.
JANITORs on duty: Pat Babcock (pbabcock at hbd dot org), Jason Henning,
and Spencer Thomas
----------------------------------------------------------------------
Date: Tue, 30 Sep 2008 08:55:45 -0400
From: "A.J deLange" <ajdel at cox.net>
Subject: pH and temperature
RE: "... no practical ways (for the home brewer) to measure the mash pH
ant mash temp. Both strips and meters are designed to measure pH of a
cooled sample. And the ATC feature of a pH meter doesn't compensate for
the pH shift of the mash."
The second part of the statement is true enough - ATC does not account
for pH shift (which is caused by the temperature dependence of the pK's,
which are measures of the energy required to remove protons from the
acids in the mash). It merely accounts for the the fact that the
response of the electrode is E0 + (R*T/F)*log[H+] with E0, R and F
being constants, T the temperature and [H+] the hydrogen ion activity
(concentration) which does in fact change with temperature through the
pK's as mentioned above. Apologies to Chad for logs 2 days in a row. It
is very important that people understand that there are two distinct
mechanisms: a) the shift in actual pH with temperature and b) the change
in the response of a pH electrode with temperature to whatever pH is
encountered.
Now the first part of the statement is not quite true. Today's meters
are generally capable of measurement at mash and even kettle
temperatures. The instructions that came with your meter or electrode
should specify the range of temperatures that it can handle.
Referring to the points above if you dunk your electrode into the mash
tun or kettle you will read the pH at the temperature of the mash or
wort provided that your meter is ATC equipped as nearly all are these
days. If you remove a sample from the same mash or wort and cool it to
room temperature you will note a rise of a couple of tenths of a point
as the mash or wort cools. Despite the opinion of giants in the industry
such as Jean DeClerck that "..the pH should be measured at the
temperature of the reaction." [Vol. I p267] it is usual to measure at
laboratory temperature and the ASBC Method for pH determination of worts
prescribes this. The clear advantage of doing so is that variation in
measured pH over the course of a mash/boil cycle are those caused by the
chemistry of the mash and are not masked by the fact that, for example,
a protein rest was done at 124 F and a saccarification rest at 149. A
not so obvious advantage is that the working part of most electrodes is
still a very delicate, very thin glass bulb which is subject to
considerable thermal stress as it is thrust into boiling wort or hot
mash and again when it is remove to cool air. This was posted here years
ago by someone who was involved in the manufacture of these things, as I
recall. I can personally testify that since I have started taking all
measurements at room temperature my electrodes last much longer and at
the prices they command that is definitely a good thing.
A.J.
------------------------------
Date: Tue, 30 Sep 2008 09:16:34 -0400
From: "A.J deLange" <ajdel at cox.net>
Subject: Brix and Plato
The work of the Normaleichungskomission under Dr. Plato was undertaken
in order to correct the Brix tables to Teutonic levels of precision.
The Brix tables in turn represent an improvement on the original work of
Balling. In all three cases the object was to obtain values of specific
gravities for solutions of sucrose of given strength by weight (i.e. 10
P or 10 Brix represents 10 grams of sucrose in 100 grams of solution).
The reference temperatures for the specific gravities were different but
when reduced to the same reference temperature the differences between
the Brix specific gravities and Plato specific gravities are in the 5th
and 6th decimal places. At the level at which refractometers and
hydrometers work, Brix and Plato are, thus, the same.
A.J.
------------------------------
Date: Tue, 30 Sep 2008 10:39:17 -0400
From: Kai Troester <kai at braukaiser.com>
Subject: Re: Mash Temp and Color
Kevin,
> I made two experimental 3 liter batches of about 10 deg P OE this
> weekend. Both were
> 100 percent Maris Otter. I mashed one at 65 deg C (149 deg F) and the
> second at
> 70 deg C (158 deg F). All other variables, as best I could control,
> were kept the same.
> (OEs were 10.4 and 10.6 deg P). Interestingly the wort from the low temp
> mash was
> noticeably darker than the high temp mash. I was not expecting the
> difference, but
> should I have? They are in 1 gallon jugs so the difference is unmistakable.
How much darker are we talking about here? Did you measure the wort
pH? I expect it to be about the same as I expect that you used the
same water for both batches.
One cause that I can think of is that the lower temperature mash
created more simple sugar and amino acids than the higher temperature.
These are the the compounds that react to during maillard reactions.
In addition to that, maybe the pH of the higher temp mash dropped
further due to the increased reaction between calcium/magnesium and
malt phosphates. Decoction mashes are known to lower the pH further as
a result the increased precipitation of phosphates.
Kai
------------------------------
Date: Wed, 1 Oct 2008 11:21:47 -0700 (PDT)
From: Jon Fischer <fischjon at yahoo.com>
Subject: acid bath for wort chiller?
Hello Friends,
I have been using a flat plate counter flow wort chiller with great
success until I recently noticed a drop in performance. I am trying
to clean it, based on the manufacturer's advice which includes a soak
in 5% food grade acid such as citric or phosphoric.
Would any of you recommend that I use a 5% solution of "Star San"?
If so, how should I make a 5% solution.
Thanks,
Jon Fischer
Columbus, Indiana
------------------------------
End of HOMEBREW Digest #5425, 10/01/08
*************************************
-------
