Should be a simple primary fermentation question

Have a question or want to show off your project? Post it! No Registration Necessary.  Now with pictures!

Threaded View


I'm embarrassed to be asking this question, because I'm a fairly
experienced winemaker.  My question concerns a persistent primary
fermentation, but the SG is not dropping.

A couple of months ago, I received a batch of botrytized juice with a
brix level of 35.  I'm trying to ferment it to the point that the
yeast dies, and I'll be left with some residual sugar.  My problem is
that it keeps bubbling away (vigorously), but the SG hasn't dropped at
all in the last 3 weeks.  It's stuck at 1.026.

I've put in a lot of lysozyme, because I don't want MLF.  Also, the
bubbles "look like" a primary fermentation.  There's been a bit of
temperature change (I warmed it up a bit up to about 76 degrees)
because I wanted to speed things up, but I can't imagine that this is
all CO2 coming out of solution.

The yeast that I originally used died when the SG was still in the
1.050 range.  That left me with too much residual sugar, so I re-
inoculated with Premier Cuvee, which has an alcoholic tolerance of 18
percent.  I realize that the Premier Cuvee might ferment all the way
down to 0, but that's ok...I can always add back some sugar and be
left with a very potent wine.  At this point, I just want things to
stop.

My alternative is to chill the wine, stop the fermentation, then
filter and hit it with sorbate...but frankly, my filtration is never
COMPLETELY sterile, and I don't like sorbate.

Any thoughts?  This is baffling me.  I can understand that the yeast
is still doing it's thing.  I just don't understand why the SG isn't
dropping.

Lee

Re: Should be a simple primary fermentation question


Lee wrote:

Quoted text here. Click to load it

You might check the temperature range of the yeast
you are using.  It may be that it is too cool for
it to do its thing the best. It might also be
worthwhile to check the pH and adjust if
necessary.  

I tried fermenting a red outside one year using
Pasteur Red.  I had a situation like yours
(except for the high brix).  I then researched
and found that Pasteur Red does not like
fermenting around 50 degrees.  I brought it into
the basement and wrapped a heating pad around the
fermenting container and introduced some EC-118.
It evenutally fermented out.  It took over three
weeks instead of the usual 10 days.

Re: Should be a simple primary fermentation question


Lee

1.  Lysozyme will not stop a full blown MLF once it is in progress.
     It may have been in the juice when you got it.
2.  Like you, I think P. Cuvee should have a way to go yet but the
     SG should be dropping slowly to indicate this.
3.  You are already headed toward "Port" style numbers, and if all
      you want to do is stop it at this point,  just add enough alcohol
      to bring it up to ~20%ABV.  This level of alcohol will kill
      everything (whatever it is) and since high alcohol prevents
      refermentation, no sorbate will be required.
HTH

        Frederick


Quoted text here. Click to load it



Re: Should be a simple primary fermentation question



Seems to me that the key issues are; 1. does the wine have sufficient
alcohol already, and 2. is the current activity mlf or yeast?

What I would probly do, in your shoes (which doesn't mean any of it is
right!) ....

* If the alcohol is sufficient at this stage, which it sounds as if it
is, refrigerate to stop any activity.
* Test the RS (I use clinitest) to ensure it is where you want it.
Chaptalize later if it needs sweetening ... but I suspect it doesn't
* Run a paper chrom test to see if there is any lactic acid present -
in other words, to determine if the current activity is mlf.
* If there has been mlf, you can still use lysozyme to prevent any further mlf
* If there has been mlf, do NOT use sorbate. Use a filtering to prevent
further activity, or as someone said, add alcohol - although the
resultant wine may be too hot or imbalanced
* If there has not been mlf, then sorbate should stop any yeast fermentation








Quoted text here. Click to load it



Re: Should be a simple primary fermentation question


How does it taste?  If it doesn't taste like you've got bacteria, why not
let it go until it is the sweetness and alcohol percent that you like? At 76
degrees you might be getting quite a ferment going.  Was the initial ferment
cold and slower?  If that is what is going on it will probably slow
drastically soon.

I have a honey grape I started in August that is still bubbling at the rate
of a bubble a minute.  It also started very sweet.  It tastes good and I am
interested in how it turns out.  Why rush it?
Mary


Quoted text here. Click to load it



Re: Should be a simple primary fermentation question


wrote:
Quoted text here. Click to load it

I am making a cranberry now that stuck the same way; it's cold here so
I tried making it in the furnace room.  The temperature excursions in
the room annoyed the yeast.  I moved it to a stable temp of  ~70F and
it picked up in two days and is proceeding down.

Joe

Re: Should be a simple primary fermentation question


Quoted text here. Click to load it

Lee:

I had some wines in the past that stalled like this, the airlock was
popping regularly at the rate of 8-12 bubbles a minute but the s.g.
drop was only about 0.001-0.002 in a month (I have a narrow range
hydrometer so can see very small drops in s.g fairly precisely). I
think what happened in those cases was the yeast population died down
a lot towards the end of the ferment for various reasons (lack of
nutrients, low temp) but not completely, so the ferment kept going. So
I would suspect just a very slow ongoing ferment in your case.

As others said, ML could also be an option so if you don't mind doing
the chromatography test, that'd narrow down the possibilities.

What style are you trying to make? It sounds like "Sauternes", in
which case you've got already more than enough alcohol in the wine and
the sugar should be on the low side, so why not just stop it now? If
you don't like sorbate (I don't either), use benzoate instead - there
was a recent thread on this. It might be ok to not add anything in the
end, if you filter the wine, th eyeast doesn't seem to be doing much
now so chances are it won't get going again once you clarify the wine.

Pp

Site Timeline