Keep getting acetaldehyde when kegging...

[nosco]

A little ot but i thought co2 being denser/heavier than oxygen created a slight protective layer/blanket over the beer from oxygen? So how would oxygen permeating cling wrap matter?

 

[manticle]

While co2 is being actively produced, there will be some resistance to o2 but it is not a brick wall and it is not permanent.

Glad is fine during active fermentation but not great for any decent length of maturation

 

[GalBrew]

A little ot but i thought co2 being denser/heavier than oxygen created a slight protective layer/blanket over the beer from oxygen? So how would oxygen permeating cling wrap matter?

Google 'gas partial pressure'. The CO2 blanket thing is temporary at best. Not to mention that cling wrap is very gas permeable.

 

[GalBrew]

Time to report back!

Ok. I'm starting to think it's *not* due to the gladwrap sorry guys. I'm pretty sure its my US05 yeast. It's probably been mishandled and thus I've been underpitching. I bought 10x at one time from a retailer I won't name and have been using it for brews over the last few months and pretty sure it is the cause of my acetaldehyde issues now.

Brewed a new belgian blonde with WB06, was done before the airlock post here so fermenter had gladwrap. No sign of green apples after a week in the fermenter, at kegging, nor after 2 weeks in the keg. It's great!

My other brew an american porter with US05 I mentioned in a previous post. Bottled. After a week in the bottle it had definite acetaldehyde aroma and taste.
Well after 3 more weeks today the acetaldehyde is pretty much undetectable. It's very drinkable now. Rejoice!

However my pale ale keg from 6 weeks ago in a keg, left to condition, and even taken out of the fridge and allowed to warm up is still green apple city.

So what I *think* I've learnt is that (as google shows) yeast health is the primary factor.
It seems that bottling and allowing to bottle condition warm helps reduce or eliminate the acetaldehyde.
However kegging and then carbing and placing straight into the fridge gives it no chance to clear the acetaldehyde. Taking the keg out and sitting it at room temp made no difference either. In future if I get the slightest whiff of green apple when kegging I'll just bulk prime and naturally carb the keg warm I think, just to be safe.

Think I'll just stop being lazy and start using liquid yeasts for all of my brews! I'll report back when my current brews with liquid yeast as ready, but no signs of green apple from the fermenters thus far. Regardless I've bought airlocks and will be using them as well on my fermenters just in case I'm going to boil the remaining US05 and use it as yeast nutrient as well!

Your problem is that there shouldn't be any acetaldehyde in your beer when you keg. Kegging and force carbing cold beer is standard. We all do it all the time and don't have acetaldehyde issues. You need to work out why you are getting acetaldehyde in the first place.