Acetalaldehyde reuptake?

[ajdelange]

...try adding a Campden tablet to 5 gallons. This will reduce the acetaldehyde to ethanol...

A little further investigation shows that this is not the most likely fate of aldehyde in the presence of bisulfite. More likely is the formation of an adduct (sulfone). The double bond is still reduced but the reaction is more like
CH3CHO + HSO3- --> CH3CHOH(SO3-)

[HighCountry]

AJ and BrewChemist: many, many thanks. I am most certainly not a chemist...the most experience I have with this level of chemistry was how to identify methyethylbadshit in fire school. Then you call the crazy ass hazmat guys and step away.

So you two are my crazy ass hazmat guys. I owe AJ a sample on a different issue, so I might as well bottle up an acetaldebock and send one your way.

BrewChemist: what's at Park Meadows? I'm up in the city regularly and can bring you some samples. I really appreciate it.

To answer the questions you guys posed:

AJ: the green apple flavor is not quite acetic or vinegary. It's more of a perceived sweetness. It's not terribly unpleasant, but it is reminiscent of an apple Jolly Rancher, so I'm pretty sure it's a classic case. The beer is not filtered. Yeast is WL 838 Southern German Lager, which seems to produce more acetaldehyde when than 830 or 833. That's just my experience, though. At any rate, I believe the acetaldehyde is yeast-generated since this beer did not attenuate fully. 69.6% vs. 73% anticipated attenuation. Not sure why this occurred, since I used three fresh vials of 838 in a 3.75 gallon starter with O2 at the start and intermittent shaking for the duration of the propagation period. Temperature was controlled at 48 during the length of fermentation for 4 weeks. Time may be the culprit, since I normally leave my lagers on the lees for 6 weeks.

The beer is increasingly bright. Color is approximately 8.8 SRM and after 3.5 weeks of lagering there is still some visible haze. I'm hoping that 3.5 weeks is not enough time to lager completely. But my guess is that I pulled it out of primary too early.

I think my best bet is to depressurize, let it sit and allow the CO2 and cold to scrub out whatever it can. Since it's unfiltered the GodisGood might just finish cleaning up after itself. This is what I get for trying to rush for nationals. This beer was fantastic last spring, and I was a little late in brewing it this year. Lesson learned.

[BrewChemistinCO]

BrewChemist: what's at Park Meadows? I'm up in the city regularly and can bring you some samples. I really appreciate it.

I work about a mile from Park Meadows. I can quantitate a few of these samples for you and try to identify specifically what your problem is. Hopefully identify possible solutions too. I can also talk to a few microbiologists here and see about acetaldehyde adsorption and ways to get rid of it.

[HighCountry]

Many, many thanks. Very cool of you to do that. You go from Westminster to Park Meadows? What a shit commute...I can't even get my truck out of the driveway right now so it will be a few days. I'll PM you for the details. You realize this kind of favor results in lots of free beer, right?

[ajdelange]

the green apple flavor is not quite acetic or vinegary. It's more of a perceived sweetness. It's not terribly unpleasant, but it is reminiscent of an apple Jolly Rancher, so I'm pretty sure it's a classic case.

Based on this and your other comments I'd say it is not an infection and I certainly hope that is the case. I think there is probably a good chance that liberal use of "tincture of time" will fix the problem.

[HighCountry]

Based on this and your other comments I'd say it is not an infection and I certainly hope that is the case. I think there is probably a good chance that liberal use of "tincture of time" will fix the problem.

Can I pick that tincture of time up at my LHBS?

Thanks, AJ.

[ajdelange]

Probably, or you can order it over the net. Just be sure you get the terestrial and not the barycentric.

[Crackin]

I ran this question past JZ once, and he told me to warm it up and add an active fermenting yeast starter. It worked pretty well, although I don't think I ever got rid of all of it, but made it drinkable.