Re-fermentation

[troutgod]

Making a Cab Sauv from juice. Starting grav 1.090, I think. I say that as after I picked up the juice it appeared to have possibly started fermentation by the time I got it home. When I checked the specific gravity it was only in the range of 1.08?. So I bumped up with some corn sugar.
Fermentation proceeded as normal and once it appeared to complete I added malolactic culture. I failed to check the specific gravity at that point...my bad.
After about two and a half months I checked the specific gravity and it was 1.008 and tasted quite sweet. So I made a new yeast starter and fermentation begin again.
It has been well over two weeks and the fermentation continues. My question is why is it taking so long to ferment a little residual sugar. Also,is it possible malolactic fermentation did not take place due to the Residual sugar and is that what I am seeing now. Thanks

 

[sour_grapes]

I'll take a shot...

I checked the specific gravity and it was 1.008 and tasted quite sweet. So I made a new yeast starter and fermentation begin again.
It has been well over two weeks and the fermentation continues. My question is why is it taking so long to ferment a little residual sugar.

It is tough to get a good colony of yeast going when you are starting them out in a hostile environment. I mean, something happened to conk out the first colony of yeast, after all. Did you initially add any yeast (to the already fermenting batch)? What yeast did you add just now? When you say "fermentation continues," what are you referring to? Bubbles in the airlock? Better to consult your hydrometer to monitor fermentation.

Also,is it possible malolactic fermentation did not take place due to the Residual sugar and is that what I am seeing now. Thanks

Seems unlikely that the sugar is what interfered with the MLF. You can coinoculate MLB with yeast during primary alcoholic fermentation, after all.

 

[troutgod]

Initial yeast was Lalvin 212 and I just added Redstar Premier Cuvée to restart.
I can see a ring of tiny bubbles in the carboy and “islands” of bubbles floating on the surface. I get a bubble in the airlock once every 30 seconds or so.

 

[salcoco]

that sound more like MLF what does your hydrometer say?

 

[troutgod]

Just checked and SG is down to 1.002 so it is apparently fermenting...slowly. Tastes like fermenting wine, too.
Still seems like a long time, but I’ll let it do it’s thing.
Thanks for your help.

 

[user 36973]

The RC212 yeast likes warm environments and is very hungry for nutrients. When I use that yeast strain I add 0.5-1.0g/L DAP about half way through to help it complete the fermentation without sticking. It sounds like your fermentation stuck at a couple % residual sugar and that can be difficult to restart. So good news you seem to have some fermentation on-going. RC212 can also put out a fair amount of H2S when it gets unhappy.

I would assume you need to re-inoculate the MLF once the primary fermentation is done. While you *can* co-inoculate the yeast and the MLF, it can be risky in cases like this where the primary fermentation sticks and leaves sugar behind that the malolactic bacteria can turn into vinegar. Hopefully your MLF were just killed off and did not cause any foul odors in your wine. Good luck.