Rework
Andrew Lea
police' happy!]
Vicky wrote:
> I'm very interested by this, what proportion juice to old cider would
> you use to re-ferment?
This is a bit of a 'how long is a piece of string?' question. In a true
commercial rework situation you would typically only be able to add
single %'s of 'out of condition' or clean reclaimed product to 'blend it
off' without affecting the core product. However, in the case of cider a
refermentation by yeast provides a positive mechanism (not just mixing)
for ameliorating certain flavour defects, so you can actually use a good
deal more.
Beech and Pollard (1957) give an example for handling acetified cider,
adding equal parts by weight of freshly pressed pomace and tired cider,
then re-pressing and refermenting. If you think about it this will not
raise the gravity very much (maybe up to 1.005?) but even this small
amount is sufficient to get the yeast to take the acetic acid and ethyl
acetate back into the metabolic pool.
Here's an example of my own. I had 120 L of cider I wanted to rework. In
the following season I blended it with just 40 L of fermenting cider
which had already reached SG 1.020, thus giving 160 L of a fermenting
composite at SG 1.005 (in a 3:1 old:new ratio). When this batch had
finished fermenting out it was just fine. I didn't use it on its own but
blended it with other cider from the current year to give a composite
total of 800 L which went for bottling. So the rework was about 20% of
the final product. Can't have done it any harm since it took a first
prize at the Bath and West Show!
I think there is a lot of latitude in what you can do. In the absence of
fresh juice, you could probably just fortify the tired cider to SG 1.005
with sugar (maybe adding some nutrients?) and pitch a yeast to finish it
off. Even that brief run down from 1.005 to 1.000 seems to be enough to
rejuvenate the whole bulk. Just let me repeat that this will not work
with alien flavours such as 'mouse'; but it is good for small amounts of
tired oxidised flavours due to acetic acid, ethyl acetate and
acetaldehyde which can all be re-metabolised by the yeast.
Hope this helps.
Andrew
David Llewellyn
cured by this method? I would consider my tongue fairly sensitive to
detecting a slight acetic taint, and I would have tank cider that I would
otherwise consider sound, apart from a faint acetic note. I had assumed that
such cider is written off apart from potentially using it for actual vinegar
production (which is probably not ideal either, as it may not be the best
strain of vinegar bacteria in there). Do you feel that a refermentation of
such a cider with a proportion of fresh juice might clear that taint?
Regards,
And a happy and fruitful new year to you and all in the group.
David L.
Vicky wrote:
Hope this helps.
Andrew
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Andrew Lea
> Andrew, are you saying that a cider with a slight 'vinegar taint' can be
> cured by this method? I would consider my tongue fairly sensitive to
> detecting a slight acetic taint, and I would have tank cider that I would
> otherwise consider sound, apart from a faint acetic note. I had assumed that
> such cider is written off apart from potentially using it for actual vinegar
> production (which is probably not ideal either, as it may not be the best
> strain of vinegar bacteria in there). Do you feel that a refermentation of
> such a cider with a proportion of fresh juice might clear that taint?
Yes I believe so. It sounds like you have a perfect candidate. As you
know the key characteristic of a slightly acetic cider is actually ethyl
acetate rather than acetic acid. The yeast can dismantle the ester back
to ethanol and acetyl CoA and return them to the metabolic pool for the
synthesis of other more interesting components (though some EtOAc at
acceptable levels will always be present too from yeast action). The
acetaldehyde will also be acted upon by yeast aldehyde dehydrogenase to
reduce it back to ethanol. Biochemically, fermenting yeast is a very
'reducing' environment and has the ability to take many oxidised
carbonyl functions back to alcohols.
I cannot give you much more detail than I already have done. In
particular I cannot advise on whether any particular yeast is better
than any other. If you believe the cider is bacterially infected, I
suppose it would be as well to add SO2 in the normal way too before
refermenting. When I refreshed my own 'tired' ciders they were not
specifically 'acetic'; but this dodge is recommended in Beech and
Pollard's book so I believe it to be sound. I do not think it will
tackle full-on vinegar though. You have little to lose by trying it -
and letting us know what happens!
Best Regards to all Cider Workshop readers and contributors for the New
Year!
Andrew
David Llewellyn
David Llewellyn wrote:
> Andrew, are you saying that a cider with a slight 'vinegar taint' can be
> cured by this method?
Andrew Lea wrote:
"Yes I believe so......You have little to lose by trying it -
and letting us know what happens!"
I will try it, and let you know what happens! But it will be some time
before I organise myself to do so, as the tainted cider has been stored at
the back of other things, well out of the way, and I'll also need wait til I
get some fresh-pressed juice to use for the job.
Regards,
David L.