Keep getting acetaldehyde when kegging...

[zeggie]

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?

 

[Adr_0]

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

 

[barls]

whats the time frames and how are you doing it?

 

[zeggie]

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.

 

[barls]

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

 

[Nizmoose]

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?

 

[antiphile]

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.

 

[zeggie]

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

 

[manticle]

Taste from fermenter and don't keg too early.

 

[MHB]

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

 

[Jez]

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

 

[zeggie]

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

 

[zeggie]

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.

 

[danestead]

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.

 

[idzy]

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.

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

 

[Nizmoose]

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

Or FG for that matter

 

[zeggie]

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.

 

[Nizmoose]

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

 

[zeggie]

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)

 

[drsmurto]

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.