Preventing Acetaldehyde

Step #1: Describe exactly what you are smelling and tasting, because acetaldehyde is pretty rare these days. Use any terms OTHER than "sour apple".

Or better yet -- have multiple certified judges taste your beer and confirm or refute what's going on.

Sorry, I just don't believe there's such a thing as a recurring acetaldehyde problem with different yeasts in small batches. Seems very very unlikely.

 

Nelson tastes like white grapes. Perhaps... that's what you're tasting??

 

I agree. Hmm. Puzzling...

Are you racking to secondary? How many days? Do you cold crash? Yeast doesn't like being jerked around too fast.

 

Don't rack off your yeast too soon...I would look at your all-grain procedures

 

That's not long at all. I have a beer been in primary for almost 5 weeks now and I'm not going to move it because there's still airlock activity and hasn't hit FG yet. Not sure why but I'm not going to touch it. I did taste a sample and it's excellent but sweet.

Yeast eats acetaldehyde, IF you don't rush them.

Patience might be just what the doctor ordered.

 

If the issue is indeed acetaldehyde, there are two ways it can happen.

1) Removing the beer from the yeast before it has had a chance to clean up the acetaldehyde. (All beer has acetaldehyde at some point. It's a normal part of the process.)

2) Oxidation of the finished beer, resulting in ethanol converting to acetaldehyde.

Ironically, leaving beer in a fermenter for a very long time (perhaps in an effort to avoid #1 above) can cause #2 if the fermenter allows O2 to get in. I recently tasted an acetaldehyde bomb (not mine fortunately) that did just this. I was puzzled until I saw the brewer's equipment/process.

 

I'd say that points toward oxidation as the culprit. (Again, assuming acetaldehyde is the problem.)

ETA: Gotta get some sleep. @dmtaylor, tag, you're it.

 

Two weeks seems like a long time for a 1 gal batch. My 5 gal batches are usually complete in 5-8 days. I would try doing a d-rest and reading these tips. http://beersmith.com/blog/2016/07/13/acetaldehyde-in-home-brewed-beer-the-green-apple-off-flavor/

 

Please describe what you are doing with the yeast, for example, how are you scaling down yeast to a 1 gallon batch? Are you using fresh yeast fresh every time? Are you repitching yeast? Rehydrating? Are there other aspects of the fermentation you can describe? OG, FG?

Can you describe your packaging process? You seem pretty insistent that this is acetaldehyde. I can think of 2 beers of mine in over 150 batches that exhibited green apple characteristic and both cases were beers that were bottle young and sampled early. I extended the warming phase of the bottles, and the problem disappeared.

To be honest, I am at a loss as to why you would see acetaldehyde after 2.5 weeks of fermentation of normal batches of beer, assuming nothing went wrong with the fermentation. Out of curiosity, have you used these yeast strains before? Could you just be detecting some normal fruity ester? They are both pretty neutral yeasts, but maybe you are sensitive to something they throw? Some people find US05 to be peachy, for instance.

 

Are you taking OG and FG readings to ensure fermentation completed?
How are you controlling the temp of fermentation? Poor temp control and cause excessive acetaldehyde production and or stop fermentation short not allowing the yeast to perform clean up.

 

Problem appears after switching to all-grain...an aldehyde not likely the problem, imho

edit: never mind after reading op's post about no bottling bucket spigot

 

That's actually a huge overpitch for 1 gallon. You could/should use just 1/10 of a pack in 1 gallon. Overpitching pisses off the yeast and thus might be leading to your problem as well.

Also, maybe try never cold crashing again. Fast reduction of temperature pisses off the yeast. Like I say............... you need to be very kind to your yeast.

Patience would also help. 2 weeks might not be long enough for them to get the job done. Try 3-4 weeks. That can help too.

Any 1, 2, or all 3 ideas should help. Good luck.