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Cider Digest #1005
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Subject: Cider Digest #1005, 20 November 2002
Cider Digest #1005 20 November 2002
Forum for Discussion of Cider Issues
Dick Dunn, Digest Janitor
Contents:
RE: pH and Acidity ("McGonegal, Charles")
yeasts again ("Mary Peters and Matt Swihart")
pH and acid relation (Andrew Lea)
White Labs Cider Yeast ("Berggren, Stefan")
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Subject: RE: pH and Acidity
From: "McGonegal, Charles" <cpmcgone@uop.com>
Date: Fri, 15 Nov 2002 21:10:25 -0600
Subject: PH and Acid relation
From: Dan Aldrich <daldrich@earthlink.net>
Date: Thu, 14 Nov 2002 12:24:33 -0500
Is there a way to calculate PH if you know the acid of fresh cider by
titration? I've been told you can't but it seems there must be a way if
you assume what the acid is from freshly pressed cider.
Thanks,
- - -d
Unfortunately there isn't anyway to calculate pH from acidty (or vice versa)
in any system as complex as cider.
pH meters and titrations measure two related - but different things. pH is
the free hydrogen ion concentration. Titrations measure acidity by
neutralizing all the possible H(+) in the solution.
Now, you might think that knowing one, you could calculate the other - but
pH depends on the ratio of the fruit acids (like malic) with their
disassociated form (with H(+) split off). That ratio varies with
concentration, exact mix of fruit acids, H(+) from other sources and cations
(other (+) ions) like potassiom, sodium, magnesium, calcium - all those good
trace mainerals.
Possibly, if you know the exact amounts of all those things, along with the
phase of the moon, you could calculate the pH - but it end up being like
predicting the weather - close, but easier to look out the window.
Handheld pH meters are _too_ expensive - and you can use one to measure the
endpoint of you titrations. That's really handy with colored juices.
Charles
AEppelTreow Winery.
------------------------------
Subject: yeasts again
From: "Mary Peters and Matt Swihart" <marymatt@gorge.net>
Date: Sat, 16 Nov 2002 07:21:01 -0800
In response to Tim Bray's query on lager yeasts...
While I have never fermented cider with a lager yeast, there is no reason
why it wouldn't work. In beer worts, lager yeasts don't ferment maltotriose,
but I don't believe that to be a component of cider musts. So I believe that
the attenuation or final gravity of the cider would be equal to or just
slightly less than fermenting with an ale strain. Fermentation would proceed
faster than with standard wine and ale yeast, as lager yeast can work quite
well at cellar temperatures, even down to 46F, although fermentation would
be quite a bit slower down that low. Bacterial populations can be somewhat
kept in check, (and that was the whole quality improvement with beer in the
late 1800s, by using a colder tolerant yeast strain) and fermenting at a
colder temperature. When fermenting at cold temps with lager yeast and with
poor nutrients (typical of apple musts), fermentations tend to produce a
little more sulfur as sulfure dioxide than ale strains. Ferments in the
upper 50s tend to reduce that character and bring out the more estery,
fruity quality of lager yeasts, which is inappropriate in lager beers, but
might be interesting in a cider.
"Beauty is in the eyes of the beerholder"
Matt Swihart
Full Sail Brewing
------------------------------
Subject: pH and acid relation
From: Andrew Lea <andrew_lea@compuserve.com>
Date: Sat, 16 Nov 2002 15:55:25 +0000
Dan Aldrich asked
> Is there a way to calculate PH if you know the acid of fresh cider by
> titration? I've been told you can't but it seems there must be a way if
> you assume what the acid is from freshly pressed cider.
There really is no direct predictable relationship between pH and
titratable acidity which works exactly the same for all apple juices.
Each juice has a different 'buffering capacity' depending on its
composition, and this depends on the apple cultivars, where they were
grown, what the weather was like etc etc.
However, that said, there are some very general 'ball park' figures
which can be derived. I recently did some regressions on the
relationship between pH and acidity in some cider apple juices, using a
statistical software package and data of my own gathered at various
times over the last 30 years or so. These were the 'best fits':
Y = 64.56*exp(-1.384*X) (exponential)
or
Y = 0.4528*X^2 -4.097*X + 9.3632 (binomial)
where Y is titratable acid in % malic and X is pH.
If anyone wants to look at the plots, they're on my website at the
following link
http://ourworld.compuserve.com/homepages/andrew_lea/pHandacid.htm
The reason it is useful to know both measurements is because pH relates
much more to things like fermentation behaviour, resistance to spoilage
bacteria, sulphite and sorbate effectiveness etc etc. - the cellular
processes of living things tend to be pH controlled. Titratable acid
relates much more to the perceived degree of acidity of the cider when
you taste it.
Andrew Lea
- ----------------------------------
Visit the Wittenham Hill Cider Page at
http://www.cider.org.uk
------------------------------
Subject: White Labs Cider Yeast
From: "Berggren, Stefan" <stefan_berggren@trekbike.com>
Date: Mon, 18 Nov 2002 10:15:12 -0600
Cider lovers,
I want to start out by saying that I have no affiliation with Whitelabs or
Chris White. However, I cannot say enough good things about the Whitelabs
cider yeast ! It is amazing and really produces a great tasting cider
constantly. The cider ferment is powerful and clears nicely with a very
compact lees. Again if you are into making a nice English style cider, than
this is your weapon of choice.
Cheers,
Stefan
This is grain, which any fool can eat, but for which the Lord has intended a
more divine form of consumption.
Let us give praise to our maker and glory to His bounty by learning about
beer. --Friar Tuck
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End of Cider Digest #1005
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