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Cider Digest #0814
Subject: Cider Digest #814, 19 June 1999
From: cider-request@talisman.com
Cider Digest #814 19 June 1999
Forum for Discussion of Cider Issues
Dick Dunn, Digest Janitor
Contents:
Cider pH (Dave Burley)
Cider and apple browning (Andrew Lea)
Some questions (Paul Haaf)
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Subject: Cider pH
From: Dave Burley <Dave_Burley@compuserve.com>
Date: Thu, 10 Jun 1999 12:09:23 -0400
Cider folks,
A few weeks ago I commented that it is a good idea to watch the pH of cider
as their low quantity of buffers allows them to fall so low as to prevent
all but the most minor of fermentations and may explain why some are
experiencing slow fermentations. A correspondent differed with my opinon
that ciders were low in buffers. Not having a quotable source, I avoided
the "does so, does not" possibilities of our differing opinions. It turns
out <some> juices do possess a low buffer capacity, so the pH should be
monitored and adjusted, keeping it above 3.2. In winemaking and meadmaking
calcium carbonate (chalk) is used for this purpose and should be fine here
even though calcium malate, as I recall, is relatively soluble, whereas the
tartrate is not.. If this is the case, perhaps tartaric acid could be used
for the final pH adjustment and the calcium ion would be removed to a large
extent.
The Lallemand article by George Clayton Cone noted in the latest Digest
(http://www.lallemand/con/brew/inferment/article/article%20cider.html) has
the following quote:
" There is very little buffering capacity in some apple juices, allowing
the pH of the fermentation to drop rapidly during the first day of
fermentation to <3.0 and seriously damaging the yeast cells. The pH should
be monitored closely for the first 18-36 hours. Unless high acidity is
required for a particular style of cider, it is best to keep the pH >3.0,
preferably >3.2, with a carbonate, during fermentation to maintain healthy
yeast. The pH can be adjusted downward after the fermentation."
Dave Burley
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Subject: Cider and apple browning
From: Andrew Lea <andrew_lea@csi.com>
Date: Mon, 14 Jun 1999 22:19:18 +0100
Dan McFeeley asked:
> I'd like to pose a question to the list about browning reactions in the
> processing of apples, and in the making of cider. Could anybody explain
> the particulars in terms of biochemistry on how this takes place, and how
> the process is controled or prevented? I'm also curious to what degree
> the maillard reaction plays a role in browning reactions in apples and
> cider.
The basic process is one of aerial enzymic oxidation mediated by a
membrane bound polyphenoloxidase. This initially oxidises chlorogenic
acid through a redox shuttle mechanism leading to quinone formation and
polymerisation of procyanidins and catechins, which give most of apple
juice colour (75%). Phloridzin oxidised by the same route gives about
25% of the colour. These pigments bind strongly to the pulp and so
soluble juice colour depends on the length of time for which oxygen and
pulp are in contact. With heavy aeration, colour reaches a maximum and
then declines, as more polymers become bound to the pulp. Conversely,
pulp held in a tall container browns only in the top few inches where
air can penetrate but remains water white below. Increasing temperature
and pH promote oxidation. Colour can be reduced by sulphur dioxide which
inhibits the enzymes and chemically reduces the coloured quinones.
Ascorbic acid reduces the quinones until it too is all used up. Apple
juice colour is lightened by the reducing action of yeast during
fermentation - typically about 50% of visible colour is 'lost' in this
way but can be regained by exposure to sterile air. Maillard browning
plays no part in traditional cider colour but is very significant in
modern commercial ciders made from concentrates which are often very
brown through high temperature storage. Maillard browning is not
reversed by yeast during fermentation.
Many more references on my web site if you go to the 'my scientific
publications' page and check out the book chapters on apple juice and
cider. Sadly these are not easily obtainable but I could send
photocopies to anyone seriously interested.
Andrew Lea, nr Oxford, UK
- --------------------------------------
Visit the Wittenham Hill Cider Page at
http://www.oxfordonline.co.uk/cider OR
http://ourworld.compuserve.com/homepages/andrew_lea
------------------------------
Subject: Some questions
From: Paul Haaf <haafbrau1@juno.com>
Date: Thu, 17 Jun 1999 21:12:24 -0400
What does 'naturally fermented' mean? I thought it meant the cider
fermented on its own. The Woodchuck Amber Cider claims to be naturally
fermented, but it lists Champagne Yeast in its ingredients. Also, what
is cold filtered? This is also labeled on the bottle. Is the Cider just
chilled for a time before bottling to drop out sentiment and yeast, or is
it more involved than that? I would imagine that this would retain
flavor better than running the Cider through a 5 micron filter. TIA
Wassail,
Paul
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End of Cider Digest #814
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