Question on stopping fermentation early!

[jh0330]

Hi, I am am making my first wild blackberry wine.
I was so excited to make wine for the first time that I made my must too sweet (SG 1.112= 14.5~15% alcohol content).
I am regretting of making my wine too strong. I am thinking I would probably enjoy drinking fruity wine at 10~13% more than 15%.
Also I was going to back sweeten a portion of my wine.

So I thought, why not stop fermentation on a portion of my wine early?
From my research I should follow the following steps:
-purchase k-meta(or campden tablets) and potassium sorbate
-filer with cheesecloth a portion of my wine that I wish to stop fermentation
(throw pieces filtered back into my primary)
-add enough k-meta to kill yeast.
SO2 + H2O <==> H+ + HSO3-
H+ + H20 = H3O+
pH=−log[H3O+]

pHbefore - pHafter = pHdifference = -log([H30+before])--[H30+before])
pHdifference = -log([H30added])
10^-pHdifference = [H30added]
Please check if i am right on this math.
Another problem is I've added 2 campden tablets prior to fermentation and I do not know my exact must volume. 2~2.5gallons.
-add potassium sorbate to make the yeast sterile (will ask clerk how to use and read instructions before use)
-let the must sit in secondary at least a week or two after the bubbler has stopped bubbling

Is this a bad idea?

 

[jh0330]

I found the search bar...
I was looking through pages after pages... haha silly me

Conclusion don't bother trying.
It is very difficult.

 

[sour_grapes]

It is extremely difficult to stop an active fermentation. There are only a few ways.

One is by sterile filtering, that is, through a filter fine enough to filter out the yeast. Home winemakers cannot really expect to do this.

Another is by increasing the alcohol (fortifying) to the point of killing the yeast. But that won't help lower your ABV, now, will it!?

Another is by pasteurizing, but that is generally thought to ruin the flavors of your wine.

K-meta does not kill wine yeast (except in extreme amounts). Not sure why Richmke, who knows more about this winemaking thing than I do, suggested that.

You are correct that potassium sorbate does not kill yeast, but only prevents them from reproducing.

I think you should just let it go dry, then rack, then add sorbate and backsweeten. Dilute with a juice to lower the ABV if you want less alcohol.

As for the math: I am really not sure where you are going with this. I am not sure why you are calculating the change in pH upon adding sulfites. Remember that you will only be adding about 100 ppm of sulfite. In any event, let me remind you that log(A+B) is not equal to log(A) + log(B).

 

[sour_grapes]

I found the search bar...
I was looking through pages after pages... haha silly me

Conclusion don't bother trying.
It is very difficult.

Arggh! Obviously I typed all that before seeing this message!

 

[richmke]

I was so excited to make wine for the first time that I made my must too sweet (SG 1.112= 14.5~15% alcohol content).
I am regretting of making my wine too strong. I am thinking I would probably enjoy drinking fruity wine at 10~13% more than 15%.
Also I was going to back sweeten a portion of my wine.

Take the high alcohol wine you have, k-meta/sorbate it, and dilute it with some unfermented juice.

That will add sweetness and lower the alcohol level.

 

[jh0330]

It is extremely difficult to stop an active fermentation. There are only a few ways.

One is by sterile filtering, that is, through a filter fine enough to filter out the yeast. Home winemakers cannot really expect to do this.

Another is by increasing the alcohol (fortifying) to the point of killing the yeast. But that won't help lower your ABV, now, will it!?

Another is by pasteurizing, but that is generally thought to ruin the flavors of your wine.

K-meta does not kill wine yeast (except in extreme amounts). Not sure why Richmke, who knows more about this winemaking thing than I do, suggested that.

You are correct that potassium sorbate does not kill yeast, but only prevents them from reproducing.

I think you should just let it go dry, then rack, then add sorbate and backsweeten. Dilute with a juice to lower the ABV if you want less alcohol.

As for the math: I am really not sure where you are going with this. I am not sure why you are calculating the change in pH upon adding sulfites. Remember that you will only be adding about 100 ppm of sulfite. In any event, let me remind you that log(A+B) is not equal to log(A) + log(B).

Thanks so much on this response,
it helped me much more and I had forgotten log(A+B) != log (A) + log(B)!!
Thanks for the advice reallly helpful ^^

 

[jh0330]

Take the high alcohol wine you have, k-meta/sorbate it, and dilute it with some unfermented juice.

That will add sweetness and lower the alcohol level.

I think I will do this.
I will have to read up more on this "backsweeten" technique.
I think it was after secondary rake it and then mix then bottle right?

 

[Bartman]

Whoa, I had to look up what H30+ was/is. Chemistry was a long time ago. I had no idea I was making Hydronium - I hope the Feds don't find out! I'd probably end up having my bank accounts frozen, getting threatened by Israel, and becoming an international pariah. Oh wait - that's plutonium.