Sluggish or stuck fermentation
Daniel Print
After the cold start to last winter and my first attempts to do long, slow, low temperature fermentations using natural yeasts coincided, I'm left with two gallon batches sluggishly refusing to drop below 1030. They are in the garage at about 17degreesC and both froze to slush puppies in the cold snaps, but after the thaw they appeared to recover. They are still effervescing gently, and are still slightly cloudy but are stubbornly sticking at a very high gravity.
I racked them in February (without taking the gravity) because they looked to be working through, but I think I may have left them without enough yeasts to work. Seeing as I'm used to cider fermenting to dryness within weeks (indoors) or months (if kept in the garage) I'm at a loss. Am I best sulphiting to kill off the existing yeast and repitching with a dose that will sort out the remaining sugar, or will summer temps and slow fermentation work it through to a more feasible gravity for bottling (even if I have to wait until autumn)?
I suspect that Sacharromyces hasn't taken charge, and that most of the drop in gravity has been due to other wild yeast. The batches are still clean and fresh, just far too sweet and only half-worked through.
In the interests of science I tested my hydrometer in water to make ssure that wasn't the cause of high readings, but no - the cider really is that slow!
Thanks
Dan
(Essex, UK)
Andrew Lea
>
> I'm left with two gallon batches sluggishly refusing to drop below
> 1030. They are in the garage at about 17degreesC and both froze to
> slush puppies in the cold snaps, but after the thaw they appeared to
> recover. They are still effervescing gently, and are still slightly
> cloudy but are stubbornly sticking at a very high gravity.
I would try the following (in sequence, waiting a few days between each
to see what happens).
1. Aeration (even just splashing from one vessel to another a few times).
2. Add thiamine (vitamin B1). The dosage rate is 0.2 ppm but if you buy
them as tablets from home brew suppliers a dose rate will be suggested.
3. Add ammonium phosphate or similar yeast nutrient. Typical dose is 300
ppm but again if you buy commercial tablets a dose rate will be suggested.
4. Those three steps should re-vitalise any existing but flagging wild
yeast. If all else fails, pitch a fresh cultured wine yeast.
The alternative to all that is to sit it out and rack at least once more
to stabilise at around SG 1.015 as a natural sweet cider.
Good luck!
Andrew
--
Wittenham Hill Cider Page
http://www.cider.org.uk
Ray Blockley
I'll start the ball rolling :-)
I'd get some dried yeast sachets from my local home-brew shop - ours sells
"cider yeasts", but otherwise any ordinary basic wine yeast will do - and
start a culture off using a sterilised bottle, some tepid water, a teaspoon
or so of sugar, then add the yeast and give the lot a good shake, plug with
cotton wool and leave for 24 hrs / overnight. I assume that some drop in SG
has taken place so those early yeasts that kick in before Sacharromyces will
/ should have started to help produce a cidery bouquet and flavour.
Two options now - add the yeast starter all in one go; or if your
fermentation is really stuck, add the yeast to say the same quantity of your
'juice' and when that is happily fermenting, double up again, then double up
again, etc. etc. - or just add to the main bulk.
I'd also keep the early stages in a warm place to get a healthy fermentation
going.
You could also consider adding a little yeast nutrient to the early batches,
again just to get a healthy population of yeasts going.
I certainly wouldn't add any sulphite - this could only exasperate a 'stuck'
fermentation.
Aerobic fermentation is also an early stage that you could enhance in your
starter phase by a little 'rough' stirring or agitation, aerobic is the
stage in which the yeasts multiply very vigorously and you get most froth /
foam.
Hope some of this may help.
Cheers,
Ray.
Claude Jolicoeur
> After the cold start to last winter and my first attempts to do long, slow, low temperature fermentations using natural yeasts coincided, I'm left with two gallon batches sluggishly refusing to drop below 1030.
If it was 1.060, you would now be at 3.8% alcohol, and 6 % residual
sugar. You would only need to ferment it a few more degrees of gravity
go get a naturally fully sweet cider.
On the other hand, if initial gravity was only 1.045, then would have
acquired only 2% alcohol by now, which is insufficient.
Claude
Daniel Print
I shall get started on those steps!
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CiderHead
season. It stopped at SG 1030 in February (OG was 1052) .
I performed the steps that Andrew suggested, except all at once, and
it all started up again quite vigorously.
The apples came from a very low nutrient background I believe - the
remains of a very old orchard in the corner of a field where cattle
were being grazed. The soil underneath was barren apart from cow pats!
Ray suggested using cultured yeast but, with all due respect to Ray,
these yeasts impart a completely different flavour to natural yeasts
(I work in a home brew shop and have tried loads of 'em!) so I would
avoid them if possible. The bouquet from the "cider" (i.e. champagne)
yeasts will overwhelm any subtleties generated by natural yeast. If
you actually want such flavours then you might as well start off with
cultured yeast in the first place and add nutrient at the beginning.
Personally, I would use this technique only as a last resort. Out of
all the cider I produce (OK, only 120 gallons per year but I do sell
it to pubs here in Bristol, UK) the least popular variants have been
the versions with "cider" yeast! Never again.
So, add nutrient and shake well.
Cheers,
Martin
Ray Blockley
> Ray suggested using cultured yeast but, with all due respect to Ray, these
yeasts impart a completely different flavour to natural yeasts (I work in a
home > brew shop and have tried loads of 'em!) so I would avoid them if
possible.
Yes, I'm very aware of that. But in my defence of mentioning yeast cultures,
as we didn't know how far gone or how dire the situation is / was, using
some (any?) form of commercial yeast culture should be considered as a _last
gasp_ "Get out of Jail" if all else has failed. I feel that is better than
the lot going off / sour / vinegar. That was my only concern and the reason
I mentioned a commercial strain. Also, and no disrespect to Dan intended, we
have an a number of absolute beginners who follow this group, so any extra
solutions to be considered should be mentioned.
As I've regularly posted up on here over the years, we don't use any yeast
cultures, relying on mother nature's agents. But that doesn't mean I'd stand
idly by and watch gallons of cider go to waste *if* all the other methods
mentioned in both my and Andrew's response failed.
Interesting though that you mention trying lots of different yeast strains.
Have you tried a beer yeast and if so, what results did you get? Reason I
ask is that someone on another forum was adamant that the best homemade
ciders were made using beer yeasts... Hmmm.
Cheers,
Ray.
brewpastor
the US. I don't have much experience with cider, but, with a few
qualifications, see fermentation as a common process. Aeration can't
be over stressed (and nearly so can't be over done!) I use pure
oxygen run through a diffusion stone to aerate my wort and must. This
is more important in beer brewing where boiling drives off available
oxygen in the wort, but even so I find strong aeration to be very
useful in obtaining a strong fermentation. Oxygen is not necessary,
and can easily be over-done, but forced air does make a huge
difference.
Likewise, yeast nutrients can also be helpful, but again I believe
aeration to get a strong fermentation is the best way to avoid a stuck
fermentation. I recognize the OP is concerned with remedying a stuck
fermentation and underscore the advice given by others. But the best
way to deal with a stuck fermentation is to do all you can to avoid
them from the start.
If there is differing information related to aeration and cider
production I would be very interested to hear it.
Dick Dunn
> My background is as a brewer, having founded and run a micro here in
> the US. I don't have much experience with cider, but, with a few
> qualifications, see fermentation as a common process. Aeration can't
Well, you've just hit a big "qualification" (that is, difference).
Aeration of apple juice before fermentation is pretty much a waste of
time in any typical situation. The juice is aerated as it comes out of
the press, and may pick up more air as it's moved about.
I asked whether aeration could be overdone, since we certainly don't want
excess air later in the cider. As I understand, the yeast will take care
of any excess O2, so it's OK. But what's the point of an extra step?
That brings to the next difference:
>...I use pure
> oxygen run through a diffusion stone to aerate my wort and must. This
> is more important in beer brewing where boiling drives off available
> oxygen in the wort, but even so I find strong aeration to be very
> useful in obtaining a strong fermentation...
Craft cidermakers generally -don't- want a strong fermentation. Rather,
they'd want it to get going and then take its time. This is particularly
important where a "wild yeast" fermentation is attempted, since a rip-
snorting start just cuts to the final yeast (some S. cerevisae).
> Likewise, yeast nutrients can also be helpful, but again I believe
> aeration to get a strong fermentation is the best way to avoid a stuck
> fermentation...
But why should it stick in the first place? We've got folks on the list
whose juice comes from old, low-nitrogen orchards (i.e., low yeast nutrient
levels). Their fermenting cider was down near freezing over the winter.
But as the weather warmed up, the cider picked up fermenting again.
Really, we've got to look deeper for the problems that occasionally cause
stuck fermentations. But they are rare.
> ...But the best
> way to deal with a stuck fermentation is to do all you can to avoid
> them from the start.
In general that's a good way to think--as in "An ounce of prevention is
worth a pound of cure"--but that's only if there's no down-side to the
preventive measures.
> If there is differing information related to aeration and cider
> production I would be very interested to hear it.
See above--not really needed (unless you're trying to blast out "product"
in a couple weeks), and for craft cider probably not even wanted.
Fixing a stuck fermentation is a different matter. At that point it's a
concern of getting it restarted and not losing it to contamination or
oxidation, so measures are indicated that might not be otherwise.
--
Dick Dunn rc...@talisman.com Hygiene, Colorado USA
greg l.
so a fairly strong, fast ferment is unavoidable for me. Even so I
don't see any need for aeration, as Dick says the press gives plenty
of oxygen to get a good ferment started.
Greg
Thomas Hart
Andrew Lea
> Well, you've just hit a big "qualification" (that is, difference).
> Aeration of apple juice before fermentation is pretty much a waste of
> time in any typical situation. The juice is aerated as it comes out of
> the press, and may pick up more air as it's moved about.
I agree with Dick's spot-on analysis. Even if you are going for a fast
2-week turnaround there is enough air in the juice to satisfy the needs
of most modern cultured yeasts. Some months back I had need to discuss
this matter with the technical manager of one of the UK's foremost
'industrial' cidermakers. He wrote that "most industrial dried yeasts
are at optimum glycogen and sterol levels if they are rehydrated to
instruction and do not benefit from aeration before fermentation".
There is also a downside to the excessive aeration of fresh apple juice
or grape must prior to fermentation, and that is that it will encourage
the polymerisation and loss of 'tannin' by activation of the
polyphenoloxidase (PPO) enzyme. Sometimes this is seen as a good thing
and is used as a deliberate technique ('hyperoxidation') in warm climate
white wine making to remove polyphenols which could cause instability
and browning later in the finished wine. Generally, certainly in ciders,
it isn't necessary or desirable to reduce tannins in this way.
As Dick says, a stuck fermentation is of course a different set of
circumstances, and the original question was about a very (too?) slow
wild yeast fermentation where aeration might indeed be of benefit.