Grodziskie Sour

[AlexKay]

So I kegged a grodziskie (smoked wheat, K97, Magnum/Saaz, 1.041/1.010) a little over two weeks ago. I set the regulator to 22 psi and left it for a week, at which point it was fine: in particular, it tasted fairly clean, though it hadn't cleared yet.

Now, after another week in the keg (it's been cold -- 34 or so -- the whole time), it's changed: it's strongly fruity/estery, with a touch of apple cider vinegar as an aftertaste. It tastes Belgian, so much so that I've gone back to the keezer twice now to make sure I'd gotten the right tap. (It's sitting next to a rye tripel.)

Can this happen? Specifically, can an infection proceed this quickly in a cold, mostly oxygen-free keg?

Thanks in advance for advice (or commiseration).

 

[AlexKay]

@#$%^&!! The cream ale I kegged the same day seems to have gone off too. Fruity/sour, this time with a hint of sulfur.

The same StarSan got used to sanitize both, and they transferred using the same length of silicone tubing. Nothing else in common.

 

[Hoppy2bmerry]

Do you have any flipping fruit flies hanging around?

 

[AlexKay]

I don't remember seeing any in the garage where I was transferring to kegs. We occasionally have them in the kitchen, though, so I guess I can't rule them out.

 

[Hoppy2bmerry]

I don't remember seeing any in the garage where I was transferring to kegs. We occasionally have them in the kitchen, though, so I guess I can't rule them out.

That would be my guess, as you report a vinegary aspect to the taste/smell. They can get into the smallest spaces and are attracted to fermentation even sauerkraut.

 

[Lefou]

I'm waiting for first frost or freeze.
I've refused to make beer for MONTHS because the kitchen has been shanghai'ed for sour doughbread and fruited kombucha by Number 1 Son. His flour and vinegar spray gets everywhere. He really needs his own kitchen.
When first frost or freeze comes it's usually a good time to brew because those little pests tend to disappear. Simple traps can be made from a small cup with apple cider vinegar and fruit rind, plastic wrap, and a rubber band. Put some of the smelly vinegar in a cup, cover with wrap, and roll a rubber band to secure it. Poke some holes in the wrap so the flies can get in. Most times they're too stupid to get back out.

 

[AlexKay]

Thanks for the advice and commiseration. So the beer got infected during the transfer to kegs, tasted ok after the first week, but infection progressed enough (at 34 F) in a week to spoil it? Or is it possible it was infected on its way into the fermenter, and not show up for three weeks, and then come in strong at four?

I'm going to boil that piece of silicone tubing, clean and hot PBW the kegs, then run it through the hoses, then repeat with StarSan. Does that sound like enough?

 

[mashpaddled]

How were you normally cleaning and sanitizing your racking equipment?

 

[AlexKay]

I have ball valves on my brew buckets, so I use gravity and that length of silicone tubing to go directly into the keg. It (the tubing, not gravity) is just washed in water and then soaked in StarSan.

The ball valves get boiled, PBW, and StarSan each time I use the fermenter. The fermenter gets scrubbed, PBW, and StarSan. The kegs get scrubbed and StarSan, with occasional PBW soaks.

I'm definitely getting a whiff of vinegar from my empty fermentation chamber, so I guess it's time to clean that.