advice on FG

[GeneDaniels1963]

I have two 1 gal batches of blackberry wine that are on the second racking. Both started out about 1.115. They are fermented with wild yeast on the berries.

One gal went down to 0.994, but the other only got to 1.013. Just to make sure, I hit the second one with some Red Star red wine yeast. Based on what I have read that should take up to 15%.

Anyway, I let them sit another 2 weeks and neither has moved. The first batch comes out at about 15.3% ABV, the other at 12.7%. I just gave them a dose of potassuim sorbate and will let them sit for a couple more weeks. But unless something changes I think they are both done.

I am sure the first one (0.994) is done, and I plan to backsweeten with some must I saved back in the freezer. The second one tastes wonderful as it is, so I want to just bottle it. But I am a bit worried about the 1.013 reading. Could it just be stalled? Is there any significant chance of it restarting now? How long should I leave it under airlock to make sure? Another 2-3 weeks?

Any advise is most appreciated

 

[dmtaylor]

If it's done, it's done. If you already waited a few weeks and it didn't move at all, you can bottle it. Lucky, no need to backsweeten!

 

[Morrey]

Have you considered blending some of the two batches together? The must could be used as a final adjustment.

 

[GeneDaniels1963]

Have you considered blending some of the two batches together? The must could be used as a final adjustment.

That's a good idea, might try that.

 

[RPh_Guy]

I just gave them a dose of potassuim sorbate

Sulfite too right? Don't want geraniums.

1.115 to 1.013 is about 15% ABV according to
https://www.brewersfriend.com/abv-calculator/
using the alternate equation.

 

[GeneDaniels1963]

No,

Sulfite too right? Don't want geraniums. 1.115 to 1.013 is about 15% ABV according to
https://www.brewersfriend.com/abv-calculator/
using the alternate equation.

No, I just use Potassium Sorbate based on some of the readings I did in the past.

As for the alternate calculation, it sure does not taste like 15%.

 

[RPh_Guy]

Lactic acid bacteria can create a strong geranium flavor in the presence of sorbic acid. SO2 is needed to prevent that

The ABV calculators are just estimates. Use whichever you want... But I like that one because it's based on a higher regression created with the help of computers. (And why did your added yeast not further drop gravity if not for the ABV?)
The sweetness and acidity could easily hide the ABV.

 

[GeneDaniels1963]

(And why did your added yeast not further drop gravity if not for the ABV?) The sweetness and acidity could easily hide the ABV.

Very good point. I was wondering about that myself.

 

[GeneDaniels1963]

The ABV calculators are just estimates. Use whichever you want... But I like that one because it's based on a higher regression created with the help of computers. (And why did your added yeast not further drop gravity if not for the ABV?) The sweetness and acidity could easily hide the ABV.

When I used the alternate calculator on the first batch I came up with 17.46%. Is that possible with wild yeast? I am guessing its possible, but...

 

[RPh_Guy]

It's a numbers game. Toss in enough strains and you'll get some that are highly alcohol tolerant (or even just one, if it's your lucky day).

These Koreans tested 600+ isolates from the surface of fruit and found 24 that were able to grow in 15% ABV media.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3385091/
I've heard the best yeast is inside the fruit, so their methods weren't even the best. Possibly why they only found one Sacc strain.

It's also plausible you had a contamination from some previously used strain floating around.

Glad your wine turned out well!
Cheers.