Off flavor when fermenting in keg... Any idea?

[frenchbrewer]

Hi!!

I am experimenting with fermenting directly in keg. The 2 first fermentations where done under pressure. The first one was a stout and good. The second one was a dobble Bock and was ... weird. FG was quite higher than expected. I put it under the pressurize fermentation fault. The taste was off. Somehow cidery almost like acetaldehyde. I was like ok it is clearly an incomplete fermentation...

My last try is in the same keg without pressure just a blow off tube. The fermentation went well. FG as expected - a little on the dry side. Now I tested it after 1 week in the fridge. Boom same taste. This off flavor I have difficulty to describe...

I cannot imagine the stainless steel being an issue. I'm thinking about too much time on the yeast? But I thought autolyze was not an Homebrewer issue..

For what it worth I only use Kveik strains so far.

 

[Dgallo]

Hi!!

I am experimenting with fermenting directly in keg. The 2 first fermentations where done under pressure. The first one was a stout and good. The second one was a dobble Bock and was ... weird. FG was quite higher than expected. I put it under the pressurize fermentation fault. The taste was off. Somehow cidery almost like acetaldehyde. I was like ok it is clearly an incomplete fermentation...

My last try is in the same keg without pressure just a blow off tube. The fermentation went well. FG as expected - a little on the dry side. Now I tested it after 1 week in the fridge. Boom same taste. This off flavor I have difficulty to describe...

I cannot imagine the stainless steel being an issue. I'm thinking about too much time on the yeast? But I thought autolyze was not an Homebrewer issue..

For what it worth I only use Kveik strains so far.

Was it Hornindal? Hornindal can throw this strange caramel/sherry thing when stressed.

 

[frenchbrewer]

Was it Hornindal? Hornindal can throw this strange caramel/sherry thing when stressed.

No weirdly it is 2 different strains. Initially it was Oslo and lately Lida...

 

[Dgallo]

No weirdly it is 2 different strains. Initially it was Oslo and lately Lida...

That is why I ruled out a Kveik specific issue...

I will say as high as 90% of all off flavors come during fermentation.

what was your pitch rate?

All kviek strains need ample nutrients or they can throw stressed flavors. I’m not familiar with Lida and I only ever under pitch Oslo so I don’t have nutritional issues.

another possibility is oxidation. Are you familiar with its flavor? Any possibility that the keg post or lid o-ring have issues?

 

[frenchbrewer]

I will say as high as 90% of all off flavors come during fermentation.

what was your pitch rate?

All kviek strains need ample nutrients or they can throw stressed flavors. I’m not familiar with Lida and I only ever under pitch Oslo so I don’t have nutritional issues.

another possibility is oxidation. Are you familiar with its flavor? Any possibility that the keg post or lid o-ring have issues?

Honestly I don't know exactly the pitch rate. I do the same starter everytime and pitch it. Again the same process I do outside of the keg in a normal fermenter.

I never tasted oxidize beer as such. I put keg lube on all the o-rings. The keg is new and holding pressure well but I cannot say during fermentation...

It feels really strange this off flavor is difficult to describe but it feels like despite FG low the beer is too sweet.

 

[Dgallo]

Honestly I don't know exactly the pitch rate. I do the same starter everytime and pitch it. Again the same process I do outside of the keg in a normal fermenter.

I never tasted oxidize beer as such. I put keg lube on all the o-rings. The keg is new and holding pressure well but I cannot say during fermentation...

It feels really strange this off flavor is difficult to describe but it feels like despite FG low the beer is too sweet.

So for kviek you can literally pitch 1tbs of slurry (seriously 1tbs) into 5 gallons of a 1.065 beer and it will finish in around 72 hours. So no need for a starter. So it’s possible it was a stressed flavor.

Here is a pretty good article on oxidation off flavors. See if their description are similar to what you are tasting
https://www.google.com/amp/s/beerandbrewing.com/amp/off-flavor-oxidized/

 

[frenchbrewer]

So for kviek you can literally pitch 1tbs of slurry (seriously 1tbs) into 5 gallons of a 1.065 beer and it will finish in around 72 hours. So no need for a starter. So it’s possible it was a stressed flavor.

Here is a pretty good article on oxidation off flavors. See if their description are similar to what you are tasting
https://www.google.com/amp/s/beerandbrewing.com/amp/off-flavor-oxidized/

I get it but I cannot understand why it is not happening with my other fermenters...

 

[Dgallo]

I get it but I cannot understand why it is not happening with my other fermenters...

Are the keg post poppets in property? If no air is getting in... then unfortunately you have to look at an infection or contamination in that keg

 

[frenchbrewer]

Are the keg post poppets in property? If no air is getting in... then unfortunately you have to look at an infection or contamination in that keg

I believe they are in because I have no leak when I put it under pressure.

It is weird to think of an infection on a new keg. I wash it with PBW and sanitize it every time... But it seems to be one of the possibilities