[dpevans]

I am trying an experiment by adding cut apples into an amble ale. I read it was best to add after primary fermentation, so I added to the fermenter after 1 week. It's been 2 weeks since I've added them and I'm still seeing an occasional bubble come up through the airlock. I was hoping to transfer to keg today, so not worried about bottle bombs, but wondering if I should leave it alone until the bubbling stops entirely.

[denny]

Take a gravity reading.  All bubbles tell you is that CO2 is being released, not necessarily that fermentation is happening.

[RC]

CO2 production never stops entirely in fully fermented beer that's sitting on the yeast cake. When yeast are done fermenting and settle and go dormant, they metabolize their glycogen reserves to say alive, and so they will still produce CO2, albeit much more slowly. And you may have added other microbes to the beer with those apple slices, which will slowly consume carbon sources in the beer and also produce CO2.

[dpevans]

Gotcha, that makes sense. The gravity was down to 1.01 when I added the apples, which I assume is adding more fermentable sugar. So I'm not sure how to account for these sugars for follow up readings to determine when it's "done". I was planning two weeks based on what I've read in How to Brew.

[denny]

Gotcha, that makes sense. The gravity was down to 1.01 when I added the apples, which I assume is adding more fermentable sugar. So I'm not sure how to account for these sugars for follow up readings to determine when it's "done". I was planning two weeks based on what I've read in How to Brew.

Just check to see if it's stable over the course of a few days.  When fermentation happens,  O2 is produced.  Some pd it is released, some of it goes into solution in the beer.  That dissolved CO2 can be released,  making it appear that fermentation is happening even when it isn't

[RC]

Gotcha, that makes sense. The gravity was down to 1.01 when I added the apples, which I assume is adding more fermentable sugar. So I'm not sure how to account for these sugars for follow up readings to determine when it's "done". I was planning two weeks based on what I've read in How to Brew.

Just check to see if it's stable over the course of a few days.  When fermentation happens,  O2 is produced.  Some pd it is released, some of it goes into solution in the beer.  That dissolved CO2 can be released,  making it appear that fermentation is happening even when it isn't

^Yeah just go with this advice. Almost certainly the yeast would be done fermenting the apple sugars after two weeks, and any additional microbes would work so slowly that the gravity, if stable, won't appreciably change anymore.

[dpevans]

This is exactly why I am happy dues-paying member of the AHA. Thanks guys.