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Cider Digest #1016
From: cider-request@talisman.com
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Subject: Cider Digest #1016, 7 January 2003
Cider Digest #1016 7 January 2003
Forum for Discussion of Cider Issues
Dick Dunn, Digest Janitor
Contents:
Tartaric/malic acid (Fred L Johnson)
Pasteurizing for sweetness plus carbonation (Fred L Johnson)
Acid and pH (Andrew Lea)
More thoughts on tannin (Andrew Lea)
FW: Cider Digest #1013, 29 December 2002 (Philip Sugarman)
Corking Sparkling Cider ("Berggren, Stefan")
Re: Acidity measurements (Claude Jolicoeur)
Acid and PH (Lee Elliott)
Calibrating Hydrometors (Lee Elliott)
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Subject: Tartaric/malic acid
From: Fred L Johnson <FLJohnson@portbridge.com>
Date: Sat, 04 Jan 2003 08:29:27 -0500
Jason asks how to convert malic acid concentrations to tartaric acid
concentrations.
Tartaric acid content = 1.1194 * malic acid content
The ratio of tartaric acid content to malic acid content is simply the ratio
of their respective molecular weights (150 for tartaric acid and 134 for
malic acid).
Of course, what one actually measures in the solution is the content of
ionizable hydrogen. Ionized hydrogen donated by these molecules is measured
by titration with base, and since both tartaric acid and malic acid
molecules contribute only one hydrogen ion each (as compared to sulfuric
acid, which contributes two hydrogen ions for molecule), the titration of
tartaric acid and malic acid are "equivalent". Of course, by stating the
acid content of a solution as the "tartaric acid" content, one is actually
expressing that if the ionizable hydrogen in the solution were contributed
by tartaric acid alone (and it never is except in a pure solution of
tartaric acid), that hydrogen would be coming from X amount of tartaric
acid.
(I think I've said too much, and enough to cause more confusion. Sorry.)
- --
Fred L. Johnson
Apex, North Carolina, USA
------------------------------
Subject: Pasteurizing for sweetness plus carbonation
From: Fred L Johnson <FLJohnson@portbridge.com>
Date: Sat, 04 Jan 2003 17:56:23 -0500
I am certain that this is not a new idea, so I present this with the hope
that someone who has experience with this would provide to me some guidance.
I wish to make a sparkling cider in the bottle that is not completely dry. I
propose to let it ferment to completion, priming the cider with fresh juice
(or perhaps dextrose), bottling the cider, allowing the cider to carbonate,
and interrupt the completion of this conditioning fermentation by placing
the bottles into very hot water for a prescribed amount of time to kill the
yeast.
Can anyone prescribe how much to "overprime" to provide the residual
sweetness, how long to allow the yeast to condition the bottle (3 days?),
how hot to heat the bottles?
Of course, if I'm creating bottle bombs, please stop me!
- --
Fred L. Johnson
Apex, North Carolina, USA
------------------------------
Subject: Acid and pH
From: Andrew Lea <andrew_lea@compuserve.com>
Date: Sun, 05 Jan 2003 08:19:24 +0000
Jason asked:
> I am curious as to how to convert total acid expressed as tartaric acid into
> total acid as malic acid. I think I need a conversion factor, does
> anyone know what this is?
Simply multiply the results obtained as tartaric by 0.893 to express
them as malic.
> Can it be assumed that a cider with a high total titratible
> acidity has a low pH, even if one cannot know one by knowing the other?
Yes that relationship is always true in a general sense. Check out
http://ourworld.compuserve.com/homepages/andrew_lea/pHandacid.htm for
some empirical data of mine on this topic.
Andrew Lea
- ----------------------------------
Visit the Wittenham Hill Cider Page at
http://www.cider.org.uk
------------------------------
Subject: More thoughts on tannin
From: Andrew Lea <andrew_lea@compuserve.com>
Date: Sun, 05 Jan 2003 08:53:03 +0000
Murdo said:
> For example you can happily eat bunches of Zinfandel
> grown just across the street from my totally inedible, instant-spitter
> Nehou. However, no one would argue that the finished cider has as much
> apparent tannin as the wine (would they?).
But surely the reason for that is that with Zinfandel nearly all the
tannins are in the skin. So you don't get to taste them as you swallow.
To extract them you have to do normal red-wine vinification, i.e.
ferment on the skins - otherwise from the free-run juice you get a
lowish tannin white wine. Whereas with Nehou (or any apple), the
tannins are present almost as much throughout the flesh as they are in
the skin and the volume to surface area is also much larger than in a
grape anyway.
>
> So, I guess if there's a question here it is this; we know about soft
> and hard (AKA bitter and astringent) tannins, but what about those
> obvious in the taste of fresh fruit versus in the taste of finished
> cider? What are the differences (if there are any), and how can the
> compounds responsible for each be reliably measured in an
> internationally standardized manner?
I'm not convinced there really are such chemical differences (there are
differences due to oxidation but that's something different again).
Mostly they are human perceptual differences due to the presence of
sugar and the lack of alcohol (both of which influence perceived tannin
taste). Binding of tannins to cell wall pectin in the intact fruit may
also have something to do with it. Measuring subtle changes in tannins
is extraordinarily difficult. HPLC will take us a litle way but... The
two leaders in this field are Ann Noble at UC Davis (for sensory effects
of tannins) and Veronique Cheynier at INRA, Montpellier (France).
Bob Sorensen said:
> If you are a person who turns
> down a hearty Cab for a lighter wine the chances are that you will not
> like very many tannins in your cider.
I think this well worth rememnbering before people get too carried away.
Over the last 30 years or so, the tannin levels in most UK ciders have
dropped significantly, to the extent that there are very few on the
market with any overt tannin taste at all (although it is important to
have some 'subliminal' levels or the mouthfeel becomes very thin
indeed). So we have a generation of cider drinkers who do not expect a
tannin taste and do not like it when they get it!
> The other aspect of fermentation that greatly affects tannin (or phenol)
> levels is the length of time that the juice is in contact with the skins
> and seeds of the fruit. It would be useful to know if Terry's results
> (below) were from free run juice. I would suspect that the keeving
> process would increase tannin levels because of the increased contact
> between the juice and the pulp, seeds and skins.
Unfortunately it doesn't work like that for apples. There are no
significant tannin differences between free-run and press juice (for
reasons given above). If anything, the tannin level during keeving
*drops* due to oxidation, and it can be manipulated specifically for
that purpose by spreading the pulp in a really shallow layer, but it
never goes up. It might do so if you fermented on the skins like red
wine but that is another question!
Andrew Lea, nr Oxford, UK.
- ----------------------------------
Visit the Wittenham Hill Cider Page at
http://www.cider.org.uk
------------------------------
Subject: FW: Cider Digest #1013, 29 December 2002
From: Philip Sugarman <PSugarman@standrew.co.uk>
Date: Sun, 5 Jan 2003 13:42:25 -0000
Dick
Happy New Year to you and all your contributors. And thanks for your
response to my submission. It was not really addressed at you of course. I
am glad have created some debate.
I guess the real issue is whether elaborate techniques of cider making are
worth the effort. Isn't there a danger of missing the wood for the trees? I
agree an elaborate scientific understanding of fermentation etc is
useful..but I bet the evidence that the interventions which are derived from
this knowledge actually work reliably is very scanty. Perhaps there is an
international database of "evidenced-based" interventions in cidermaking
which have been tested in controlled trials and shown effective? We all know
one or two the cider makers who could have PhDs in pomological fermentation
science but whose cider is pretty awful. And then there are many experts
like Andrew Lea who cider is quite excellent.
Your point on exploding bottles is a good one - I now have a much cooler
stone barn and have learnt not to bottle too early when I have added sugar.
On Keeving - Andrew's summary is interesting. I tend to think of Keeving as
synonymous with racking off but this is only one small part of it - I guess
the term refers to the whole "french technique" starting with letting the
grass grow in the orchard to starve the apples of nitrogen.
Andrew - why does low ph make keeving difficult?
Philip Sugarman
------------------------------
Subject: Corking Sparkling Cider
From: "Berggren, Stefan" <stefan_berggren@trekbike.com>
Date: Mon, 6 Jan 2003 12:55:35 -0600
I am curious about corking my cider (will be a sparkling cider) with wine
corks. I plan on using a #9 1.75 (high grade cork) and leaving a small
amount of cork above the lip. Then making my own wire hood likethe ones
explained in Cider by Annie Proulx. I will be using champagne bottles and
belgian ale
bottles so I know that they are sturdy. I am wondering if the cork will
provide sufficient closure to prevent loss of CO2 when second fermentation
takes place. Has anyone ever tried this with Belgian ale bottles and or
Champagne bottles? There does not seem to be a lot of information out there
about peoples experiences.
Cheers,
Stefan in Madison, WI
There is more to life than increasing its speed." --Gandhi
------------------------------
Subject: Re: Acidity measurements
From: Claude Jolicoeur <cjoli@gmc.ulaval.ca>
Date: Tue, 07 Jan 2003 01:05:35 -0500
Jason MacArthur wrote:
>Subject: Acidity measurements
>From: "Jason MacArthur" <jasonmacarthur@hotmail.com>
>Date: Thu, 02 Jan 2003 13:19:41 -0500
>
>I am curious as to how to convert total acid expressed as tartaric acid into
>total acid as malic acid. My titration kit reveals the former, I would like
>to know the latter. I think I need a conversion factor, does anyone know
>what this is? Can it be assumed that a cider with a high total titratible
>acidity has a low pH, even if one cannot know one by knowing the other?
If your cider has 1% acidity expressed as tartaric acid, as given by
standard wine titration kits in N. America, this is equivalent to 0.65% as
sulfuric acid or 0.89% as malic acid.
Malic acid equivalent is most often used for cider and sulfuric acid
equivalent is generally used in French wine making books.
For your 2nd question, yes, generally, higher titrable acidity means lower
pH. But, as you say, there is no exact conversion factor between pH and
titrable acidity. A while ago, I made some tests and plotted measured pH vs
%titrable acidity. A fairly good fit was obtained with the following formula:
pH = 3.585 - log T
where log is base 10,
T is % acidity expressed as tartaric.
15 points were used for the fit (scientifically speaking, this is a much
too small sample). Titrable acidity ran from 0.4 to 1.8% and pH ran from
3.86 to 3.39. Maximum error between the curve and the measured points was
0.15 on the pH scale.
I make no garantee on the exactness of this formula...
Claude, Quebec.
------------------------------
Subject: Acid and PH
From: applehilorchard@webtv.net (Lee Elliott)
Date: Tue, 7 Jan 2003 07:07:49 -0600 (CST)
It would seem to me that acid content and ph are the same thing
(directly proportional) Is that so and if so can you convert one to the
other? If must had a %tartaric of .60, would that equal a certain ph?
Lee Elliott
------------------------------
Subject: Calibrating Hydrometors
From: applehilorchard@webtv.net (Lee Elliott)
Date: Tue, 7 Jan 2003 07:17:04 -0600 (CST)
Am I wrong in thinking that you can check calibration of a hydrometor by
putting water in it. Shouldn't plain water read exactly 1000 spec.
gravity? Lee Elliott
------------------------------
End of Cider Digest #1016
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