Acetaldehyde Correction

[CTBrewer]

We have a 40 bbl batch of Blonde Ale that has an abundant amount of Acetaldehyde. I can say with confidence that it is from ending fermentation prior to reaching its terminal gravity. I say this with confidence as we have never had infection issues and there was not an issue with excessive head pressure in the fermenter. When I was away last Friday the beer was filtered to a brite beer tank where it currently sits. What can I do to correct the issue? Can I warm the beer up and re-pitch the yeast to rid the beer of Acetaldehyde? What steps can I take to correct the problem, if any?

[TL Services]

Acetaldehyde is very volatile, so warming would help - although be careful you don't over do it and damage your flavour compounds.

Additionally you could try gas washing to help the flashing-off of the rogue but again take care you're not also losing the things you want to keep.

I'd be a little 'slow' to repitch - presumably you skimmed initially because you were down to gravity, so repitching would just counter that.

[beerking1]

As CTBrewer states, you can bubble CO2 through to off-gas the acetylaldehyde, but be careful not to bubble off too much other aromatics.

The traditional approach is krausening. Rather than repitching, I would warm it up to the low end of your ale ferment temp and add some light ale in high krausen. The active yeast in the fermenting beer should get right to work cleaning up after the prior incomplete ferment.

[Ted Briggs]

Ditto on Krausening- you need an active ferment for the yeast to convert that over. From now on watch your pitch amount and yeast health- slow and stuck ferments due to underpitching are usualy the cause.

[TL Services]

From now on watch your pitch amount and yeast health- slow and stuck ferments due to underpitching are usualy the cause.

Just a question for CTBrewer, prompted by this - did you actively end the fermentation early or did it just stop?

[Goon Boy]

Acetaldehyde is very volatile, so warming would help - although be careful you don't over do it and damage your flavour compounds.

Additionally you could try gas washing to help the flashing-off of the rogue but again take care you're not also losing the things you want to keep.

How long and at what pressure should you 'gas wash' with CO2? I've tried doing this at 1.0bar for an hour but I'm concerned about over carbing the beer.

Has anyone used Potassium Metabisulfite to get remove Acetaldehyde? If so:
- How much did you use and how did you get it into solution?
- Was it successful?
- Did the resulting sulphur blow off?
- Any other flavor by products as a consequence?

Thanks.