Unintentional sour

I brewed up 10 gallons of Centennial blonde just over 3 weeks ago. Pitched a third generation of WLP001. Checked the gravity after two weeks, and it had gone from 1.052 to 1.042, held in the chamber at 65F. I was thinking that this was my first stuck ferm. But, I left it alone, raised the temp to 70 and checked yesterday. Now down to 1.010, but each fermenter is cloudy as hell, and tastes like Granny Smith apples. Very tart and sour. I'm not a big sour fan, and certainly did not intend to make a sour.

Outside of just putting these fermenters in a corner and forgetting them for a while, is there anything I can do with this beer to recover it?

 

No, if it's souring then you can't really stop it. I'd stash them away for a while and see what becomes of them. Might be good!

 

The first thing I would do is check the temperature in the chamber with a different thermometer. Your beer should have been fermented out with 2 weeks at 65 but it might have been really slow to ferment if it was 55 instead.

Since your ferment went really slow, I think it is cloudy because it isn't quite done yet and the sour you taste is from acetaldehyde, an intermediate product of fermentation that will be consumed with time at a higher temperature. Try raising the temp a few more degrees and give it a week and I'll bet the sour is gone.

It's really hard to get a bacterial infection that would give you a sour beer if you leave the beer in the primary. Those bacteria need oxygen and they can't get it in the primary unless you intentionally introduce it.