Beer somehow became sour during cold crashing.

[Morganmurdick123]

So I had brewed a Pilsner about a month ago, everything went great during the fermentation. Went from a OG of 1.048 to a FG of about 1.008. Tasting my gravity reading when I hit my FG it tasted perfect. Once I had cold crashed it and kegged it I noticed when I was cleaning out my fermenter it smelt kind of sour but I kind of brushed it off. When I tasted it today though to see how the carbonation was going it was very sour. Which leads me to believe somewhere in the cold crashing process it became sour?? Any ideas?

I fermented at 50°F for almost 2 weeks before I reached 80% attenuation then ramped up to 62°F for a diacetyl rest for about a week. Tasting my final gravity sample everything was fine. Then I cold crashed 2° every 12 hours until reaching 34°F, let it sit for 3 more days and then kegged.

I am very strict with my sanitation regime and I close transferred to a purged, sanitized keg.

Does anyone have any ideas of what could of happened? Any insight would mean a lot.

 

[bailey mountain brewer]

What do you ferment in? Any chance of suck back during cold crash?

 

[hotbeer]

Change up what you use as a sanitizer every so often or just use chlorine bleach on everything including the keg and give it the 10 to 20 or so minutes it needs to work well, before you go about your normal sanitizing routine.

It'd only be a guess as to where something went wrong for you.

 

[VikeMan]

Change up what you use as a sanitizer every so often or just use chlorine bleach on everything including the keg and give it the 10 to 20 or so minutes it needs to work well, before you go about your normal sanitizing routine.

Using various sanitizers is a good thing. But bleach causes pitting on stainless steel.

 

[hotbeer]

Using various sanitizers is a good thing. But bleach causes pitting on stainless steel.

For ten to twenty minutes with chlorine bleach mixed to the proper ratio, it shouldn't be any issue for pitting.

For me it's always been overnight soaks that might cause SS and other metal parts to pit.

 

[VikeMan]

For ten to twenty minutes with chlorine bleach mixed to the proper ratio, it shouldn't be any issue for pitting.

For me it's always been overnight soaks that might cause SS and other metal parts to pit.

You are a bigger risk taker than I. Also worth mentioning is that bleach can remove SS's passivation layer, which would happen before it got to the pitting stage.

 

[hotbeer]

You are a bigger risk taker than I. Also worth mentioning is that bleach can remove SS's passivation layer, which would happen before it got to the pitting stage.

True, but I've never had an issue with passivation. For 304 SS it pretty much passivates itself with just exposure to the air. A little heat from an oven or burner will speed that up.

I certainly have never had to use anything to passivate the SS pots, containers and other things I have. Even after scrubbing on them with steel wool or sandpaper.

 

[hotbeer]

I actually just put full strength Clorox bleach in a SS lid for one of my pots and left it for twenty minutes. I had the lid cocked to the side so the bleach only stayed on half of it.

After rinsing and drying I can't tell which side the bleach was on.

Of course this is just anecdotal and maybe circumstantial. So YMMV. But I have never had reason to fear bleach and SS.

Now plain old table salt thrown in a pot of simmering water (or maybe it was simmering food of some other sort instead of just water) and left undissolved on the bottom for a while, I've had that cause some pitting.

 

[bwible]

1) How long was the beer at final gravity? Its supposed to stay at the same gravity for at least 3 days to be considered finished. Beers that keep fermenting below final gravity are a sign something is wrong, if your recipe is supposed to stop at 1.012 for example, and it doesn’t stop at 1.012 and remain there for days but instead continues down to 1.005 then thats a sign of a problem. You don’t rack the beer or keg the beer as soon as it reaches a number.

I bought a Tilt hydrometer and I love it for this purpose. It keeps all the data points and makes a little chart for you even. Shows you gravity and activity in real time.

2) If it tasted fine at bottling/kegging then sources of contamination could include racking canes and tubing, any sugar used if not boiled, any spoon or anything you stir with if not sanitized, the receiving keg and keg lid if not sanitized, or anything in the airlock that might have been sucked in by cold crashing. If your fermenter has a faucet, that has to be cleaned and sanitized also. Do you suck start your syphon? Thats a no-no. Did you ever use this fermenter to make a sour or a belgian, etc, before? Some sources of infection, especially the ones that cause souring, can be stubborn and hard to eliminate. If Star San isn’t doing the job try iodophor at hospital sanitary strength. Iodophor will stain plastic and tubing orange. Most tubing and plastic are cheap to replace and should be replaced regularly anyhow, especially when trying to fight contamination.