Yeast starter turned to Sour?

[Riggs401]

I decided on Saturday to do a last minute batch. Everything was going great, until it came time to pitch. I had harvested some heady topper yeast about 6 months ago, did a yeast starter, pitched some in the batch, and saved the rest.

I stored it in a growler, and left it in the fridge for 6 mos. When I went to pitch on this batch, I started pouring, and the color was slightly off, a pinkish. So I smelled it and it smelled like a sour. I immediately grabbed another growler of a known good strain (eccentric ale yeast) and pitched it. That one smelled fine.

I tasted the soured yeast starter and it tasted like a sour, but with a lack of hop flavor (expected).

I think I'm answering my own question, but if I continue fermenting at 68 degrees, can and will it sour? I keep reading that lacto sours at 100. I wouldn't be opposed to the idea, but needless to say, I sure messed up with my yeast starter.

 

[microbusbrewery]

Lacto sours faster at warmer temps, say 100 - 114F, but it'll sour at room temp, just slower. Most lacto strains are pretty sensitive to hops so they'll struggle if IBUs are higher than 10-ish and/or with lots of late additions (even of IBUs are low, hop oils coat the bacteria, interfering with their ability to metabolize sugars).

 

[Riggs401]

Thanks for the response! I brewed an IPA that should be around 70 IBU, so from what you mentioned, it sounds like I should be clear. I'll probably age a bottle or two for experimentation.

 

[microbusbrewery]

Unless it's pedio that got in there, you'll probably be fine in the timeframe that most people would plan to go through an IPA. Pedio on the other hand is pretty hop tolerant...but it works slower than lactobacollus, so you're probably still ok.