Vigorous Bubbling, With No Sugar Left To Eat... ?

[Brego Brew]

My Cyser fermented to 0.998 almost three weeks ago, and began to clear slowly soon after.

About one week ago today I popped off the bung to do double-check on the gravity and to see how things were going and as I expected, the moment I popped the bung, Co2 bubbles began rising to the surface at quite a steady pace. They kept coming for a good long while, and I finally decided to give the carboy a swirl to see what would happen, no splashing just a light swirling. That was one week ago today and it is this morning bubbling so Vigorously that it looks like active fermentation has started back up, and it will not cease.

I would assume that fermentation has started to again to finish off even the most negligible amounts of sugar, but the Cyser is still clearing, which I would also assume means that sugar fermentation is not taking place.

Could the yeast be metabolizing something else in the mead? If it's just co2 would it really continue gassing off Vigorously on it's own for a Week!?

Thanks,
Jonas

 

[Chevette Girl]

I had one batch that bubbled for years. Not always a lot of airlock activity but bubbles would rise to the surface if carboy was gently swirled. Strawberry wine with not more than 9% alcohol. Literally, my notes say SG was .990 in Oct/05 and "still bubbling!" notations as late as 2008. Finally hit it with campden tabs, but got a report from a friend who put a half-bottle of it in the fridge after I finally bottled it that it started bubbling again in the fridge, with no available sugar!!

 

[AToE]

Degassing can take a loooooong time, that's likely what you're seeing.

 

[Medsen Fey]

If you haven't sulfited it, you may be seeing malolactic fermentation which causes bubbling.

 

[wayneb]

If you haven't sulfited it, you may be seeing malolactic fermentation which causes bubbling.

...and which can take anywhere from 6 weeks to several months to complete.

 

[AToE]

I've got to start a discussion on MLF soon, I'll give it it's own thread though. When it's come up before Oskaar has made it clear he thinks it's rarely worth doing in a mead (even a melomel) and won't have much effect because there's just not enough malic acid to be a problem... but I think my blueberry meads are aproaching similar levels of acidity/fruit as a red wine and apparently malic acid is the main acid in blueberries.

Anyways, we'll leave that to it's own thread.

 

[mmclean]

I would love to see this discussed, especially as it pertains to blueberries.

 

[AToE]

I'll see if I get time to start the discussion later today. I want to start it out with a bunch of things Oskaar said in another thread I started that MLF came up in, plus I want to discuss some stuff my research lead me too on the morewinemaking website.