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Sorbate Shelf Life


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#1 Vitruviano

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Posted 31 August 2009 - 10:30 AM

does sorbic acid have a shelf life?
I have searched this topic and found maybe's but haven't found a definitive answer. If it does expire when dry, it should also expire in solution which makes me wonder if my sweetened wines are ticking timebombs for refermentation - once the sorbate has expired. Anybody? blink.gif

#2 Vitruviano

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Posted 31 August 2009 - 07:16 PM

Now that I've had some time to research this question it appears that dry Sorbic Acid has a 3 year shelf life post manufacturing. That is what the manufacturer states:
http://www.kemira.co.....Grade PDS.pdf
However, in solution the autoxidation is much more rapid. A study in the Journal of Agriculture and Food Chemicals , Nov. 1980 pgs.1246-1249 states 90% of sorbic acid is decomposes in solution within a year. One decomposition product is caproic acid - the very same lipid that gives goats their gamey aroma - yuck. This same article claims that sorbic acid decomposes very little in dry form. Perhaps the manufacturer is giving a best by date vs. an actual expiration date. There are a number of chemical factors that prolong the life of sorbate in solution - namely absence of Oxygen. Have any of you experienced spontaneous refermentation after a year or so in your sweetened wines? Personally my early drinking wines rarely last that long in storage. V smileycheers.gif

#3 Jack Keller

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Posted 31 August 2009 - 09:35 PM

QUOTE (Vitruviano @ Aug 31 2009, 08:48 PM) <{POST_SNAPBACK}>
A study...states 90% of sorbic acid...decomposes in solution within a year.... Have any of you experienced spontaneous refermentation after a year or so in your sweetened wines?

Vitruviano, you're not thinking about this correctly. Potassium sorbate, which produces sorbic acid in wine, effectively neuters any yeast in the wine, leaving them incapable of reproducing. Within a month or two, they simply die of old age. Even if they somehow manage to outlive the half-life of the sorbic acid, they are physiologically incapable of reproducing and kindling a wholesale refermentation. If you use appropriate doses of potassium sorbate in conjunction with potassium metabisulfite, your wine will become biologically stable and you can sleep well.


#4 Vitruviano

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Posted 01 September 2009 - 03:31 AM

QUOTE (Jack Keller @ Sep 1 2009, 12:07 AM) <{POST_SNAPBACK}>
Vitruviano, you're not thinking about this correctly. Potassium sorbate, which produces sorbic acid in wine, effectively neuters any yeast in the wine, leaving them incapable of reproducing. Within a month or two, they simply die of old age. Even if they somehow manage to outlive the half-life of the sorbic acid, they are physiologically incapable of reproducing and kindling a wholesale refermentation. If you use appropriate doses of potassium sorbate in conjunction with potassium metabisulfite, your wine will become biologically stable and you can sleep well.


Jack,
That's what I needed to hear! Thank you for your enowisdom. I suppose if sorbate were just a microbe-stat there would be corks popping annually. Thanks - V smileytoast.gif

#5 Noontime

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Posted 01 September 2009 - 04:47 AM

QUOTE (Jack Keller @ Sep 1 2009, 12:07 AM) <{POST_SNAPBACK}>
Vitruviano, kindling a wholesale refermentation

A clear, thorough, and concise explanation as usual; I was also intrigued by your word usage (kindling)...I got a very cool visual. smileytoast.gif
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