# Keep getting acetaldehyde when kegging...



## zeggie (2/10/15)

It's driving me nuts! Ive been brewing for years but have only recently started kegging. At a guess over half of my beers that I keg have acetaldehyde.

Never ever had this when bottling. 

Ive focused on being more careful with sanitation, making sure not to oxidize when siphoning to the keg...cant seen to stop it.

Would priming the keg with dextrose and keeping at room temp to carb help?

Any tips guys?


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## Adr_0 (2/10/15)

Could be young,or could still be oxidation of alcohol back to acetaldehyde. More time, pre-purge with CO2, less splash?


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## barls (2/10/15)

whats the time frames and how are you doing it?


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## zeggie (2/10/15)

Last batch was in fermenter 3 weeks. Started at 18c then raised to 21c in steps in the second week. Rehydrated us05.

Put co2 into keg via liquid post. Used a sanitised auto siphon to slowly amd gently fill the keg.

Keg prv to purge oxygen. Regulator 12psi and into the fridge. I didnt touch it for 2 weeks.

Still has acetaldehyde.

Batch i did directly before this i bottled on purpose and no trace in that one.


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## barls (2/10/15)

what were the figures on the beer.
was it tasting clean before racking?


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## Nizmoose (2/10/15)

This might be out of the question for you but maybe consider trying a natural carbonation with the keg by priming the keg with sugar and leaving the keg wherever you leave bottles for two weeks to see if a second fermentation puts the issue to bed?


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## antiphile (2/10/15)

Hi Zeggie

You sound way too experienced to make the mistake of confusing acetaldehyde with acetic acid (from _acetobacter_ infection), but I'll throw this in just in case.

Palmer says acetaldehyde is:


> A flavor of green apples or freshly cut pumpkin; it is an intermediate compound in the formation of alcohol. Some yeast strains produce more than others, but generally it's presence indicates that the beer is too young and needs more time to condition.


Acetobacter is an infection that causes a strong vinegar smell and taste. I can vouch its a hard one to get rid of as I had it last year. I thought I'd done a good job of cleaning all the equipment and brewing area but it was still evident in the next batch. It then took me 2 or 3 days to strip down everything and use chlorine on everything I thought could withstand it (including walls, ceiling, benches etc), boil almost everything, and use heaps of sodium percarbonate and starsan too. That finally solved it but was a real PITA. For your sake, I really hope thats not your problem!

Cheers mate.


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## zeggie (3/10/15)

Yeah its definitely acetaldehyde. Green apple. Beer tastes fine otherwise. No vinegar.

Admittedly i havent been tasted from the fermenter...ill have to start doing that. 

Going to try natural carbing. Cheers


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## manticle (3/10/15)

Taste from fermenter and don't keg too early.


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## MHB (3/10/15)

Acetaldehyde is almost exclusively an attribute of yeast and or yeast management, US-05 isn't particularly prone to making lots of it.
The one big giveaway would appear to be that its not there in the bottles and is in the kegs, which indicates that the late "secondary" fermentation is also cleaning up the Acetaldehyde.

Reading what you have posted it sounds like your temperatures are reasonable and your problem is most likely to be yeast/pitch related, so a couple of things to think about: -
Are you pressure fermenting - too high a pressure too early in the ferment can cause problems
Under pitching yeast - If the beer is taking 3 weeks to be ready for packaging you are under pitching, primary should be over in 7 days max!
Unhealthy Yeast - Rehydrating yeast can (should) be beneficial but it has to be done properly, look at your procedure, accurately measure water temperature etc. You could be killing half of your yeast by trying to help it whish would mean you are in effect under pitching.

If you put up some more detail as to your yeast use it might help pin down the exact cause, Acetaldehyde can be a bit ticklish sometimes the cause and the cure sound like they are the same, both under and over pitching can cause more acetaldehyde, but over pitching tends to be self repairing and the fix becomes one of process rather than ingredients.
Mark


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## Jez (3/10/15)

Are you using new taps or 2nd hand? When I first started kegging I had what sounds like almost the identical issue. Everything kegged tasted like green apple when I'd previously had no issues when bottling. After trying everything under the sun to fix things with no luck I finally changed my 2nd hand floryte taps I'd got from eBay for brand new celli taps and it went away instantly. Maybe break your taps down and give them a brutal cleaning or even try using a bronco tap and see if that changes anything


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## zeggie (4/10/15)

Using a bronco tap now...all i have. About to buy taps so will test that too.


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## zeggie (30/10/15)

Bump.

So 2 batches on, both bottled. One is great but the other is green apple city. So definitely not to do with kegs. I do not keg/bottle early which seems to be the biggest trigger. Both these beers spent 4 weeks in the fermenter. It's driving me nuts as its not consistent. 


However I've realized that every brew showing acetaldehyde was fermented with US-05. Possible link? Anyone else experienced this? Ferment temperature? I normally ferment at 18 and bump it to 21 after a week or so.


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## danestead (30/10/15)

Its probably not going to help this thread and your issues but I stopped using us05 after getting consistent competition feedback of diacetyl, even though I was doing diacetyl rests etc. After a year of not using us05 the diacetyl feedback has stopped but now im getting acetaldehyde feedback. All my competition beers are CPBF from the keg and I dont taste acetaldehyde on tap at home. I am hoping its oxidation causing the acetaldehyde in the bottles. I am very careful when bottling but if the reports still continue I may have to look at bottle onditioning for competitions. I also recently spiked some beers with an acetaldehyde off flavour kit so I know the flavour and aroma, however my taste buds are definitely not sensitive right down at the average flavour threshold level as stated on the kit.


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## idzy (31/10/15)

zeggie said:


> Bump.
> 
> So 2 batches on, both bottled. One is great but the other is green apple city. So definitely not to do with kegs. I do not keg/bottle early which seems to be the biggest trigger. Both these beers spent 4 weeks in the fermenter. It's driving me nuts as its not consistent.
> 
> ...


Would be interested to know if there was a difference in the OG between the one with and without?


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## Nizmoose (31/10/15)

idzy said:


> Would be interested to know if there was a difference in the OG between the one with and without?


Or FG for that matter


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## zeggie (31/10/15)

porter OG 1059 - US05 - green apples - FG 1012
pale ale OG 1055 - BRY97 - no apples - FG 1011

Previously beers with acetaldehyde were 2x pale ale and an IPA using US05.

Since these were bottled this time, I've got the porters in a warm spot >20c so hopefully after fully carbed the yeasties can convert it.

Currently in the fermenters is a hefeweizen with WLP380 and an IPA with WLP090. Let's see if liquid yeasts avoid this green apple curse.


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## Nizmoose (31/10/15)

This has gotten me beaten. 3 weeks in the fermenter is definitely enough time. Have you made any starters? I'd be inclined to make a us05 and target a pretty monster pitch, overpitch and see if you get the green apple. Pretty weird that this problem has popped up all of a sudden


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## zeggie (1/11/15)

Made some big starters with the liquid yeasts,hopefully that helps.

Maybe I've got dodgy or old US05. Expiry is mid next year but maybe I've been underpitching if it was stored incorrectly prior. (I always keep my yeast in a 4c fridge)


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## drsmurto (1/11/15)

It won't solve your problem in regards to where the acetaldehyde is coming from but you can remove it by adding potassium metabisulfite. 

Start out small, 1g in just enough hot water to dissolve it. Give the keg a gentle swirl. Taste after 24 hours. If it still has acetaldehyde repeat the dose.


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## 1974Alby (1/11/15)

are you using an air-lock or gladwrap?...I found glad wrap was causing me issues with acetaldehyde when leaving beer in primary for more than 2 weeks. A 7-10 day ferment was fine, but if it sat too long post-fermentation, oxygen would premeate the glad wrap. I have now stopped using glad wrap and returned to air-locks ..no more acetaldehyde!


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## SimoB (1/11/15)

Change the yeast, you never know. I don't like US-05 anymore, I changed up to liquid yeast and I noticed a huge difference in the quality of my beer. I've had troubles with US-05 in the past, it's probably down to my brewing practices, but it can't hurt trying. I understand US-05 is perfectly fine and could be nothing related to your problem, but that's my view.

-SIMo.


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## zeggie (1/11/15)

Albainian said:


> are you using an air-lock or gladwrap?...I found glad wrap was causing me issues with acetaldehyde when leaving beer in primary for more than 2 weeks. A 7-10 day ferment was fine, but if it sat too long post-fermentation, oxygen would premeate the glad wrap. I have now stopped using glad wrap and returned to air-locks ..no more acetaldehyde!


Holy crap, its about the time I got new fermenter and started using glad wrap that the issues started... Just did a Google and found a few comments like this. Getting rid of glad wrap ASAP now!


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## danestead (1/11/15)

zeggie said:


> Holy crap, its about the time I got new fermenter and started using glad wrap that the issues started... Just did a Google and found a few comments like this. Getting rid of glad wrap ASAP now!


Please report back once you have fermented a couple more batches. I'd like to see if you get rid of your problem by simply using a lid again.


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## Diesel80 (1/11/15)

Never use a lid, leave all beers in primary for 2-3 weeks then 2-3 weeks CC.
I keg, but dont use US-05.

hmmmm....

don't experience the same issue.

Cheers,
D80


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## zeggie (2/11/15)

From google it might be the pressure that causes it. The gladwrap does tend to expand like a balloon. I don't prick a hole or anything.

Will report back in a few weeks after 2 more batches.


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## manticle (2/11/15)

Pressure? 

Should be no need to prick a hole (defeats the purpose).

If using plastic wrap, I'd recommend using it for primary only but I wouldn't be sure it is the cause of your problems.

Anyway try the yeast change and try the lid change separately and see what makes the biggest difference.

I've known krausening to reduce acetaldehyde but was interested to hear about the campden from drsmurto.


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## Diesel80 (2/11/15)

Are you sure the Flavour in the keg is acetaldehyde? Could it be carbonic bite from newly force carbed keg?

Does it clear up after a while?
Do you force carb at serving pressure over time or high pressure over shorter time?

I used to get a sharpness with force carbed beers that only lasted a few days then dissipated. It happened when i tried to rush the carbonation.

Cheers,
D80


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## fraser_john (2/11/15)

Albainian said:


> are you using an air-lock or gladwrap?...I found glad wrap was causing me issues with acetaldehyde when leaving beer in primary for more than 2 weeks. A 7-10 day ferment was fine, but if it sat too long post-fermentation, oxygen would premeate the glad wrap. I have now stopped using glad wrap and returned to air-locks ..no more acetaldehyde!


Can attest to the problems Albainian has stated he had, many club comp nights his beers had this problem .... and now that he mentions it, you are right, have not detected acetaldehyde in your beers recently!!! Glad it worked for you!


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## zeggie (2/11/15)

Yeah certain its acetaldehyde. Have done fault/taint tests before. Def not carbonic bite, I'm experienced with that and the latest affected batch was bottled in PET bottles.

Sick of apple beer so next batches will be with airlocks AND liquid yeasts, if either or both fixes it I'll be happy.


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## Diesel80 (2/11/15)

brew apple cider? 

Cheers,
D80


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## Nizmoose (10/11/15)

Make sure you keep us posted on the results of these next few lidded batches zeggie! Really interested in the results


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## chaositic (11/11/15)

Yeah I'm very interested in the outcome of this. I have what I suspect is a similar problem I'm just not sure exactly what I'm tasting.


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## Cube (11/11/15)

Obviously you are holding your tongue on the wrong side of your mouth when pouring.

h34r:


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## zeggie (12/11/15)

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!


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## drsmurto (12/11/15)

zeggie said:


> 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.
> 
> ...


As i mentioned, you can remove acetaldehyde by adding potassium metabisulfite to the keg. It works, I've done it a few times. I do the reverse in the lab at work, add acetaldehyde to remove sulfite. 

Obviously you want to prevent it from occurring in the first place but this is a quick way of fixing up an undrinkable beer.


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## Nizmoose (12/11/15)

I wouldn't jump off the dry yeast bandwagon! I would argue that a starter is good for yeast health regardless of the packaging method


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## mfeighan (12/11/15)

DrSmurto said:


> It won't solve your problem in regards to where the acetaldehyde is coming from but you can remove it by adding potassium metabisulfite.
> 
> Start out small, 1g in just enough hot water to dissolve it. Give the keg a gentle swirl. Taste after 24 hours. If it still has acetaldehyde repeat the dose.


Cheers for the info Smurto, I wish i knew about it with one beer i made last year! I am still unsure however if the apple flavour i got was more from my home grown hops. If you still have some of that stuff left over Dano I will drop over and drink some 'off' beers with you haha


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## zeggie (13/11/15)

DrSmurto said:


> As i mentioned, you can remove acetaldehyde by adding potassium metabisulfite to the keg. It works, I've done it a few times. I do the reverse in the lab at work, add acetaldehyde to remove sulfite.
> 
> Obviously you want to prevent it from occurring in the first place but this is a quick way of fixing up an undrinkable beer.


Thanks for the advice. I'm cautious to add stuff to the keg, but since it's barely drinkable I'll give it a whirl!


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## danestead (14/11/15)

Mikey said:


> Cheers for the info Smurto, I wish i knew about it with one beer i made last year! I am still unsure however if the apple flavour i got was more from my home grown hops. If you still have some of that stuff left over Dano I will drop over and drink some 'off' beers with you haha


Yeah man still got 1 acetaldehyde vial left. Also have heaps of others. Will chat to u tomorrow about what ive got.


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## nosco (14/11/15)

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?


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## manticle (15/11/15)

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


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## GalBrew (16/11/15)

nosco said:


> 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.


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## GalBrew (16/11/15)

zeggie said:


> 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.
> 
> ...


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.


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