Off flavour after kegging?

[Adamkav]

If anyone has some insight or had similar issues, please let me know!

I brewed a blonde ale, kegged and immediately bottle about a dozen for a friend(bottle conditioned).
Force carbed the keg and after a week or so tasted it. Initially thoughts were: Wierd esters and fusel alcohols... not clean at all (I didn't make a yeast starter after all) 1 pk Imperial yeast about 2-3 months old.
Still ..would drink a few pints over the next couple weeks.. then opened one of the bottle conditioned ones.. no off favour!

Next beer I made a hazy pale ale, kegged up, great beer, no off flavours, success! (made a yeast starter)

Next beer: Italian pilsner.. made a yeast Starter with escarpment labs Isar yeast (yes I had proper pitching rate, using recommended lager pitch rate, fermented in temp controlled chest freezer)
After six weeks, kegged up and... same fusel alcohol, estery, harsh bitterness..

So.. I gather it's not fusel alcohol from an underpitched wort like I had thought for the blonde ale.. the only thing I can think of is excess pbw? However I'm always super careful and hot rinse anything after a wash like.. 4 to 6 times because I don't want any pbw in my beer!

From the flavours described does anyone know what this is? I really don't want to brew another batch just to have this same probably (especially a 6 week lager!)

Details:
All Grain
10 Gal Ss brewtech kettle
Mash king plastic mash tun
Immersion wort chiller (copper)
Glass carboy fermenter
R O water treated with 2g ca cl, 4g gypsum, 4ml lactic acid
Mash temp 149
Worth mentioning:
All my beer consistently comes out dryer than expected (82% attenuation roughly)
The Italian pilsner came in at 1.0000 FG!!

 

[Bobby_M]

149F mash temps expectedly produce a highly fermentable wort. If you don't want that, mash at 152, 154, whatever it takes.

It sounds like you have a handle on most best practices but using a glass carboy might suggest that you're simply open racking to your keg. The bottle conditioning mitigated any oxygen damage while poor kegging process wouldn't. You can actually oxidize a beer back to having acetaldehyde which can express as solventy, green apple, and even vegetal like pumpkin flesh. Describe how you get the beer from the carboy to the keg and I can tell you how to improve that.

 

[uweschmitt]

The Italian pilsner came in at 1.0000 FG!!

How long did you ferment? Off-flavors could also be caused by an infection with wild yeasts, but then it would take much longer than a usual ale fermentation to reach FG. I had this.

 

[hottpeper13]

Same thing happened to me with a barrel aged triple. The half that was corked and caged is awesome and the keg is nail polish remover.
I brought it off tap and to 64* and was going to add 6 oz of honey and 3 grams of cbc yeast. Is this a good way to fix it or can't it be fixed?

 

[wdavis2003]

Sounds like the yeast was happy and healthy in the bottle munching on additional sugars at room temp while the yeast in the keg didn't get a chance to finish their job at much colder temps. You didn't give any details on the fermentation.

 

[Adamkav]

149F mash temps expectedly produce a highly fermentable wort. If you don't want that, mash at 152, 154, whatever it takes.

It sounds like you have a handle on most best practices but using a glass carboy might suggest that you're simply open racking to your keg. The bottle conditioning mitigated any oxygen damage while poor kegging process wouldn't. You can actually oxidize a beer back to having acetaldehyde which can express as solventy, green apple, and even vegetal like pumpkin flesh. Describe how you get the beer from the carboy to the keg and I can tell you how to improve that.

I close transfer using c02 at about 2psi

 

[Adamkav]

How long did you ferment? Off-flavors could also be caused by an infection with wild yeasts, but then it would take much longer than a usual ale fermentation to reach FG. I had this.

I fermented at 50C for about 10 days before slowly increasing temp for D rest. Held for a couple days, then slowly back down to 2C for 2 weeks

 

[Bobby_M]

I close transfer using c02 at about 2psi

That's a good start. How did you ensure there was no oxygen in the keg prior to filling it?

 

[Adamkav]

That's a good start. How did you ensure there was no oxygen in the keg prior to filling it?

Filled with sanitizer and purged with co2

 

[Bobby_M]

I'm out of ideas on the oxidation front, but no mention of diacetyl rest. You may still have issues with residual acetaldehyde if you're not bumping fermentation temps up a few degrees towards the end of fermentation. Bottle conditioning will usually scrub it because it does grow some new yeast and many people store the bottles at elevated temps above fermentation temps to get the carbonation to happen.

 

[Adamkav]

I'm out of ideas on the oxidation front, but no mention of diacetyl rest. You may still have issues with residual acetaldehyde if you're not bumping fermentation temps up a few degrees towards the end of fermentation. Bottle conditioning will usually scrub it because it does grow some new yeast and many people store the bottles at elevated temps above fermentation temps to get the carbonation to happen.

I did perform a diacetyl rest, as mentioned in a reply above