Repitch Yeast

[Grey Ghost]

I have brewed a Imperial Oatmeal Stout that had a OG of 1.103 it is now down to 1.060 I am going to repitch some yeast. Should I oxygenate? I use pure oxygen with a .5 micron stone.

 

[Ozarks Mountain Brewery]

I would add more oxygen yes, how ever you can, just not too much and only if its stalled, usually what I do is just shake it a few times, not add pure oxygen

 

[The Brew Mentor]

Why re-pitch?
Is there trouble with the fermentation?
The only oxygen I'd add would be to a starter and then add a healthy, active slurry to it.

Brian

 

[SwampWater]

How long has it been fermenting?

 

[GernBlanston]

I agree with the Mentor. Don't add oxygen to the fermentor at this stage, If you need to re-pitch, make a starter that is well oxygenated and pitch while it is highly active. If you just dump yeast into a partially fermented beer that already has some alcohol, and with the O2 used up, it may not do anything.

 

[Nosybear]

And I agree with both: Don't add oxygen after about 24 hours into fermentation. You're courting wet cardboard/sherry oxidation flavors by doing so. Make a fresh starter, well-oxygenated, and pitch it while it's still fermenting - don't wait for the yeast to floculate out. Swampwater's question is a good one as well: How long has it been fermenting? You started above 1.1, that's a very big beer. If you aren't where you need to be after a week, no worries as long as it's still fermenting. But likely your yeast gave out in the anaerobic, acidic, alcoholic environment of that very big beer. Next time:
- A monster pitch, a two-liter starter at minimum.
- Extra oxygen BEFORE 24 hours into fermentation.
- If you can, use oxygen, not air, for oxygenation.
- Consider finishing the last third of the beer with a supplemental yeast. Champagne yeast works well, just be sure you hydrate it, or use a fresh starter of something like San Diego Super Yeast.