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Cider Digest #1618
Subject: Cider Digest #1618, 10 March 2011
From: cider-request@talisman.com
Cider Digest #1618 10 March 2011
Cider and Perry Discussion Forum
Contents:
Pressure inside a bottle (Andrew Lea)
Flex tanks in cider making? (Joshua W)
Fermentation vessel options (Richard Schoeler)
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Digest Janitor: Dick Dunn
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Subject: Pressure inside a bottle
From: Andrew Lea <andrew@harphill.co.uk>
Date: Sun, 06 Mar 2011 19:57:23 +0000
Joseph Conway wrote:
>
> I wonder if any of the cider makers on this list have come up with a way
> to determine what the pressure in the bottle will rise to at the highest
> temperature reached in the hot water bath. So for those who like practical
> physics, here's an example:
>
> Say the final amount of CO2 dissolved in the cider at bottling is 2.0
> volumes of CO2. The highest temperature for pasteurization reaches 64
> degrees C in the bottle.
>
> Q: What is the pressure in the bottle at this temp?
A: 5.8 bar (ca 87 psi).
This is an application of Henry's Law see
http://en.wikipedia.org/wiki/Henry%27s_law You can set up the equations
on a spreadsheet and get the pressure for any vol of CO2 at any
temperature.
The relevant equations (to be read in conjunction with the Wikipedia
article) are
KH = 0.034*EXP(2400*((1/T)-(1/298))) where T is the temp in degrees K
(i.e. degrees C + 273)
CO2g/L = CO2vol * 1.964.
CO2mol = (CO2g/L)/44
P(bar gauge) = (CO2mol/KH) - 1
These give data identical to the many published carbonation tables, at
least for temperatures up to 30C. I am assuming that these relationships
continue to be valid at somewhat higher temperatures too. These
equations are strictly only valid for CO2 in water, but the effect of
sugar and alcohol on CO2 solubility is actually rather slight.
At 10C the pressure in the same bottle computes as 0.7 bar
At 20C it is 1.3 bar
At 30C it is 2.0 bar
E&OE
Andrew Lea,
nr Oxford UK
www.cider.org.uk
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Subject: Flex tanks in cider making?
From: Joshua W <wagnerjb38@gmail.com>
Date: Sun, 6 Mar 2011 21:21:37 -0500
Hello,
As a light weight and low cost alternative to stainless steel, Flex Tanks
have gained popularity among traditional wineries. The tanks are designed
to replicate the oxygen exchange rates of oak barrels, and offered in
different thicknesses. However, I have not found mention of their use by
any cider makers. Is this due more to allegiance to traditional materials
or to some perceived limitations with polyethylene? From a cost standpoint
they appear very attractive, but I'm concerned about potential spoilage.
Any thoughts would be appreciated.
Thanks,
JW
------------------------------
Subject: Fermentation vessel options
From: Richard Schoeler <rcschoeler@yahoo.com>
Date: Wed, 9 Mar 2011 10:58:29 -0800 (PST)
I am interested in what fermentation vessels others are using for 20-25 and
40-50 gallon volumes. I've been using cornies for fermentation and storage but
intend to increase production next year to a level (80-100 gallons) that makes
their use less practical for fermenting. Ideally I would like to continue to
transfer product to corny kegs with CO2 for storage/dispensing and avoid the
need for/use of a pump, but if you have a good solution that involves a pump,
I'd like to hear about it. Specific product information and sources would be
most appreciated. Thanks.
Richard S.
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End of Cider Digest #1618
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