stuck fermentation

[chefse...@gmail.com]

Hi Everybody

I think I have a stuck fermentation and would appreciate some advice.

cider was pear and apple (50/50)

Ph-3.5

TA- 7.21

OG- 1.062

Yeast- Wyeast Cider yeast 4766

30/3 -Pitched yeast and put in temperature controlled environment at 14 degrees celsius

3/5 -Fermented down to SG 1006 so racked to secondary and topped up with more juice

11/5- checked gravity again and was at 1012 

28/5- checked gravity and still at 1012

Can anybody advise on the best way to get this one moving again. I note the advice in Andrew's book was to add nutrient, however I did add nutrient initially (the one that comes with the Wyeast packet that you smack together in the packet).

Should I add more at this stage? 

Also Andrew's book says vigorous aeration for 30 minutes but not sure what this means exactly. Vigorous stirring or shaking. Will this not cause undesirable contact with the air?

[Andrew Lea]

Consider the fact that if you have a lot of pears there, you may have a high residual SG due to non fermentable sorbitol. In which case the fermentation is not stuck, it is finished. 

Andrew

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[chefse...@gmail.com]

Hi Andrew

Okay thanks for that. The flavour is still quite sweet, would that make sense is there is sorbitol.

Is there any way to check if this is the case, or should I just let sit and see if any re- fermentation occurs

[Andrew Lea]

I don't think a person can easily distinguish between the sweetness profile of sorbitol and that of normal sugars. (Others may disagree).  There is no easy way to tell the detailed sugar composition short of a lab analysis. The simplest way is to watch and wait. 

You could try adding extra nutrients or thiamin (vitamin B1) to a test portion of course, to see if fermentation starts again. 

Andrew

Sent from my iPhone

[chefse...@gmail.com]

Okay Andrew sounds good. I might try the test as it would be good from a learning point of view to see what happens. How much thiamin to use for a 100ml ?

[Andrew Lea]

My book / received wisdom says 0.2 ppm thiamin. That's just 0.02 mg per
100ml. Tiny. But it won't matter if you overdose a bit. I have some
Youngs B1 tablets which claim to contain 3 mg B1 and they say add 1 or 2
per gallon (5 litres). That's 0.6 - 1.2 ppm actually. But going on their
dosage rate you'll need 1/50 of a tablet for 100 ml. Don't try to cut
the tablet! Do it by serial dilution of a stock solution in water.

On 28/05/2013 08:47, chefse...@gmail.com wrote:
> Okay Andrew sounds good. I might try the test as it would be good from a
> learning point of view to see what happens. How much thiamin to use for
> a 100ml ?
>
> On Tuesday, May 28, 2013 5:38:21 PM UTC+10, Andrew Lea wrote:
>
> I don't think a person can easily distinguish between the sweetness
> profile of sorbitol and that of normal sugars. (Others may
> disagree). There is no easy way to tell the detailed sugar
> composition short of a lab analysis. The simplest way is to watch
> and wait.
>
> You could try adding extra nutrients or thiamin (vitamin B1) to a
> test portion of course, to see if fermentation starts again.
>
> Andrew
>
> Sent from my iPhone
>

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[chefse...@gmail.com]

Right, thanks Andrew I will source some tablets over here (Melbourne, Australia). I am assuming I will get them from homebrew suppliers if they are a yeast nutrient, if not I am thinking health shop/ vitamin supplier. I will then proceed with your dosage rate figures using a stock solution

[Claude Jolicoeur]

Andrew Lea wrote:
> I don't think a person can easily distinguish between the sweetness profile of sorbitol and that of normal sugars. (Others may disagree).  There is no easy way to tell the detailed sugar composition short of a lab analysis. The simplest way is to watch and wait.
>
> You could try adding extra nutrients or thiamin (vitamin B1) to a test portion of course, to see if fermentation starts again.

On a recent perry I did, I couldn't know what would be the finished
SG: I was at 1.009, is it finished or could it still go lower???

What I did was to take a 1 liter sample, add a good dosage of
nutrients plus a bit of yeast, and leave it to ferment at room
temperature. This quickly fermented to dryness and stopped at 1.003.
It took a bit over a week. This is an easy way to know where you stand
with a fermentation... Once you know where your finished SG is, it is
much easier to take the right decision on what should be done with
this cider.
And as suggested, better to try on a sample bottle before doing the
whole batch...

Claude

[chefse...@gmail.com]

Hi There,

Okay I have just completed the experiment.. that is I took a sample of my cider and added nutrient and more yeast (champagne) to it and left it for a week in a warm spot.

It has now fermented down to SG 1005 (from SG 1012) and all signs of activity have ceased as of a couple of days ago.

So therefore I assume this means there is still some fermentable sugar left in my bulk cider, the rest of the gravity reading being the high sorbitol content left from the pears.

so next question...should I now proceed to treat my bulk cider with this process (champagne yeast and nutrient in appropriate quantities).

[Claude Jolicoeur]

chefseraf...@gmail.com wrote:
> It has now fermented down to SG 1005 (from SG 1012) and all signs of
> activity have ceased as of a couple of days ago.

> so next question...should I now proceed to treat my bulk cider with this
> process (champagne yeast and nutrient in appropriate quantities).

Next question is rather: what sort of perry do you want?
dry or medium dry?
still, petillant or sparkling?

Depending on the answer to the above questions you would use different
strategies...
And by the way, is your perry relatively clear by now? And when did
you start it? You did mention you were in Australia - is this this
year's perry? if that is the case, this is extremely fast
fermentation. My own perry, which I mentioned in a previous message,
was started last fall, is now just about ready to bottle...

Claude

[chefse...@gmail.com]

It is this years perry, started 30/3. 

Yes, I have been learning more about the whole process and now understand that is a fast fermentation. I did try to slow fermentation down by lowering temperature to 9 degrees celsius (I have the  Perry in a chest fridge with heat pad and external thermometer) but the Wyeast that I used couldn't tolerate the lower temp and stopped so I raised it back to 14 degrees.

Next year I will try a wild yeast fermentation which will tolerate cold temps more and also not use nutrients to attempt to slow fermentation down considerably more.

As far as this perry goes..

Yes it is quite clear now.

I would prefer medium dry and sparkling. I was intending to ferment to dryness, back sweeten with sugar to 1010, pasteurise (in bottles using hot water) and keg to force carbonate.

However now it has stopped at 1012 do you think I should rack now and let it age before pasteurising and kegging. I suppose there is no need to ferment to dryness and then add more sugar if it has stopped where I want it to be anyway?

[Claude Jolicoeur]

chefseraf...@gmail.com wrote:
> Yes it is quite clear now.
> I would prefer medium dry and sparkling.

This is the most difficult! You could easily have it medium dry and
still by bottling it as is - it would possibly ferment a little bit in
bottle to give a perlant or very slightly petillant. But you wouldn't
have a full sparkling that way.
Or you could bottle with some nutrients and yeast, and you would then
obtain a dry sparkling - if the SG drops from 1.012 to 1.005 (i.e. a
drop of 0.007) in bottle this is perfect for a sparkling, as such a SG
drop produces approximately 4 volumes of CO2.

To obtain a medium dry and sparkling, it would be a bit more
complicated. If it is well stable as it is now, you could simply force
carbonate it as is. But before doing this, I would suggest to rack and
leave it at least a month or two to be sure it is well stable, then
carbonate - pasteurization wouldn't be required if it is stable.

Claude

[chefse...@gmail.com]

Okay, thanks very much for your advice Claude.

I will rack and let sit, don't intend to drink it for a few months anyway to let it improve for a while.

If all stable then I will just carbonate and drink as is

[chefse...@gmail.com]

And just a couple more questions.....

If I leave my perry at 1010 and just force carbonate and drink as it is (which is what I would like to do)..

what are the chances of the perry re-fermenting?

Will their be more chance of re-fermentation as the weather warms up in the (Australian) summer?

Will there be less chance of re-fermentation the longer I leave the Perry to sit? Will 6 months or longer decrease the chance? Does the yeast die off eventually?

Lastly, once I keg it and put it in the keg fridge at 5 Celsius will that should remove any last risk of re-fermentation? The yeast, according to the Wyeast website, has a temperature tolerance of 15-24 celsius, and I assume my original PMS treatment would have removed any other yeasts.

thanks

[Claude Jolicoeur]

chefseraf...@gmail.com wrote:
> And just a couple more questions.....

> what are the chances of the perry re-fermenting?
> Will their be more chance of re-fermentation as the weather warms up in the
> (Australian) summer?
> Will there be less chance of re-fermentation the longer I leave the Perry
> to sit? Will 6 months or longer decrease the chance? Does the yeast die off
> eventually?

You will have your answers once you rack it and leave it for a while.
If after a month or two no fermentation has occured, there is no
reason why it would restart later. Note you need a good hydrometer to
evaluate this. Temperature is a factor however: if you leave it after
racking at a very low temperature, you might erreneously conclude it
is well stable. But if your temperature is higher than 10 or 12C, if
some fermentation is to occur, it will happen at those temperatures.

I mentioned the hydrometer above - with a standard triple scale
hydrometer you can't evaluate the SG with a better precision than +/-
0.002. So imagine the following situation:

- you measure SG today, and obtain 1.010, but the true SG is 1.012 -
you have a measurement error of -0.002
- next month, you measure the SG and obtain 1.010 again, and conclude
the perry is well stable. But in reality the SG is 1.008 and you have
an error of +0.002. In fact the perry will have dropped its SG by
0.004 during this month and you have measured it as stable!

This is a bit of an extreme example, but it illustrates that the SG
measurements may be misleading when time comes to evaluate if a cider
or perry is well stable. A good quality hydrometer and temperature
correction are essential when doing this...

>
> Lastly, once I keg it and put it in the keg fridge at 5 Celsius will that
> should remove any last risk of re-fermentation? The yeast, according to the
> Wyeast website, has a temperature tolerance of 15-24 celsius, and I assume
> my original PMS treatment would have removed any other yeasts.

Sure, if you leave it in the cold it wouldn't referment.
Claude

[chefse...@gmail.com]

Hi Claude

Okay, so I will definitely invest in a higher quality hydrometer. To be honest I didn't even know there were higher quality ones, I thought they were all the same. As it so happens I dropped my hydrometer and broke it yesterday and need to buy a new one so good timing!! I will research where to buy a better quality one over here and check SG regularly over next couple months.

 

I understand your example and I can see what you mean about the problems of inaccurate readings. Temperature control is not a problem as the Perry is in a temperature controlled environment at 14 Celsius, so this is high enough that fermentation will re-start if Perry is not stable.

thanks very much for your advice, really appreciated!

[chefse...@gmail.com]

Hi Claude

By more accurate hydrometer do you mean a digital one? If so can you recommend an appropriate one?

Also, by temperature correction do you mean the temperature of the sample? If so, a good quality digital thermometer is also needed?

[vince wakefield]

I think what Claude means is a hydrometer that covers a smaller range, I have just bought one from vigo that has a scale from 0.990 to 1.020, with divisions at 0.0005, the scale is 75mm long for that range and it’s very easy to read

 

Vince

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[Claude Jolicoeur]

chefseraf...@gmail.com wrote:
> Hi Claude
>
> By more accurate hydrometer do you mean a digital one? If so can you
> recommend an appropriate one?
>
> Also, by temperature correction do you mean the temperature of the sample?
> If so, a good quality digital thermometer is also needed?

I use precision hydrometers that have graduations at 0.0005.
Some have a range from 1.000 to 1.070, and others from 1.000 to 1.050.
I also have seen some which have a range like .980 to 1.020.
There are also some in Brix that do well, for example 0 to 8 or to 10
Brix, with graduations at 0.1 Bx (equivalent to 0.0004 in SG).

They are somewhat similar to the triple scale ones, but cover a much
smaller range hence permit to read with a better precision.

You may also find a thermo-hydrometer - these contain a thermometer in
the body of the hydrometer, thus permitting to measure the temperature
of the cider at the same time as the SG - and if the temperature
differs from the calibration T of the instrument (usually 60F) you may
then apply a correction. Otherwise, you would measure the temperature
of the cider with a standard thermometer.

A good thermo-hydrometer sells for about 30-40$ in America - so no
need to go to digital instruments that would be much more costly. Some
wine making supply stores carry good hydrometers, or they may be
acquired from laboratory equipment suppliers such as Cole Parmer for
example. Try googling for lab equipment supply in Australia, and you
should find something.

Claude

[greg l.]

Winequip sell hydrometers.

http://www.winequip.com.au/Hydrometers/

Greg

[chefse...@gmail.com]

Okay got it, thanks everyone I am on the right track now!