High alcohol kills or just stunts lacto?

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Feb 20, 2017
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I’ve had a rough lacto infection in many beers. I’ve replaced all my plastic and conducted an alkaline PBW followed by acidic Star San apocalypse on all my gear. I had already made a quad before I realized how widespread my problem is.

The quad has no signs of infection. I was hoping to use the cake on another beer.

If we assume that there’s a chance that some lacto got in to this beer but was quickly neutralized by the high alcohol, is the lacto actually dead and this beer in effect sanitized any lacto out? Or is the lacto just dormant and if I were to pitch, say, a blonde on this, it would show up again?

I’m not positive the lacto is in it, of course, I’m just trying to decide if I’d rather gamble on making another beer and having it infected, or tossing a perfectly fine cake for no reason. The cost will be about the same either way, I just end up with twice as much bad beer in the first circumstance.


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Apr 8, 2008
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Madison, WI
I believe production of lactic acid by lactobacillus is stunted by hops and lower pH, but not as much by alcohol. Check this out. Since you made a quad (low hop levels), and you suspect you had infected equipment at the time, i would suspect lacto could be present but just hasn't showed up yet. Sounds like you've got a handle on the scope, though, if you've already replaced your gear.

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