2 Different Brews, Same Yeast, Same Off-Flavor:

[MrEggSandwich]

So I posted this https://www.homebrewtalk.com/f39/soapy-taste-session-ipa-438992/ thread on 10/24 after tasting a session IPA in which I detected a "soapy flavor".

Last night, I tasted a pumpkin ale I brewed using a slurry of WLP090 that was sitting in the fridge since April (both beers were brewed in Sept). I did starters with both, and both fully fermented. The pumpkin ale has the same soapy, flavor to me. Dissappointing.

-Both used slurrys of WLP090. Did starters for both.

-Both fully fermented.

-Temp on session IPA was dead on and constant throughout fermentation (67-67).

-Temp on pumpkin ale ran hot when I woke up next morning (75+), I put it on ice, it cooled down, then ramped back up to nice temp (65-67 range).

I though the soapy flavor of the IPA may have been from cascade, but the pumpkin only has .5oz of magnum for bittering, so it's not the hops.

Main culprit here is the "old" WLP090. I've never tasted this off-flavor in any of my brews.

Thoughts?

 

[waldzinator]

So I posted this https://www.homebrewtalk.com/f39/soapy-taste-session-ipa-438992/ thread on 10/24 after tasting a session IPA in which I detected a "soapy flavor".

Last night, I tasted a pumpkin ale I brewed using a slurry of WLP090 that was sitting in the fridge since April (both beers were brewed in Sept). I did starters with both, and both fully fermented. The pumpkin ale has the same soapy, flavor to me. Dissappointing.

-Both used slurrys of WLP090. Did starters for both.

-Both fully fermented.

-Temp on session IPA was dead on and constant throughout fermentation (67-67).

-Temp on pumpkin ale ran hot when I woke up next morning (75+), I put it on ice, it cooled down, then ramped back up to nice temp (65-67 range).

I though the soapy flavor of the IPA may have been from cascade, but the pumpkin only has .5oz of magnum for bittering, so it's not the hops.

Main culprit here is the "old" WLP090. I've never tasted this off-flavor in any of my brews.

Thoughts?

Not to call out the obvious, but are the pumpkin and IPA the last two brews you've made? I'm asking because maybe it is a change in your process or cleaning regimen. Alternatively, maybe the way you cleaned your storage vessel for your slurry?

EDIT: You said the slurry was sitting since April. Did any of your fermentations with that yeast culture get up high in temperature? Hot fermentation temperatures break down lipids into soapy-like compounds.

 

[MrEggSandwich]

Not to call out the obvious, but are the pumpkin and IPA the last two brews you've made? I'm asking because maybe it is a change in your process or cleaning regimen. Alternatively, maybe the way you cleaned your storage vessel for your slurry?

Thanks for the reply...Yes, these two are the last two I have made. I have not made any changes to my cleaning process, I only use PBW + hot water overnight, dump in morning, then refill with hot, clean water.

Edit: In total, I made 3 beers with the WLP090 slurries. One in May? = No off flavors there (That I recall)...The pumpkin got hot, no doubt, but the IPA was in perfect range (67-68).

 

[duboman]

Soap by definition is the salt from fatty acids which can be present in the trub layer in the primary. Because you used a slurry of old yeast it is possible this was present in the yeast.

Unfortunately this will not age out or go away and I would suggest you no longer use that slurry for any further batches.

 

[progmac]

definitely the yeast

 

[waldzinator]

Soap by definition is the salt from fatty acids which can be present in the trub layer in the primary. Because you used a slurry of old yeast it is possible this was present in the yeast.

Unfortunately this will not age out or go away and I would suggest you no longer use that slurry for any further batches.

Agree, based on OP's statement that there was no change to cleaning regimen and that fermentation temps got hot, the breakdown of lipids caused the soapy taste (and likely mouthfeel). Toss out the WLP090 you've been using and get a fresh tube. Also in the future, keep those temps in order!