Lacto vs yeast questions

[rmeskill]

So I was posting some of this elsewhere, but I figure it makes sense to pull it into its own thread. I've spent some time poking around the forums but haven't found any specifics, so here goes...

I just brewed my first Berliner Weiss with White Labs WLP677 lacto strain. OG of 1.039, could only keep it at ~80*, but let it run for about a week, at which point I boiled it like lots of recipes call for. Except I didn't consider my SG at that point was 1.012, meaning I probably boiled off most of my alcohol. So my first question is this: how much of a gravity drop should I expect from a lacto-only strain? I've started a new batch using the same lacto strain (just fed up to a starter-size, not a new tube from WL)-I guess I should presume my lacto strain is contaminated with yeast at this point, and I don't plan on boiling this time anyway, so at what point should I add a proper yeast, or should I even bother? I have to believe, now that I think about it, 1.039 - 1.012 must be at least partially a yeast ferment, no? I don't mind a very sour beer, but I want to make sure I get some alcohol in there, too. My plan at this point was waiting 48-72 hours and then adding some US-05 just to make sure I get some yeast activity. Thoughts?

 

[sweetcell]

a pure lacto shouldn't drop gravity more than 2-3 points.

white labs' lacto strains are known for being contaminated with yeast. sounds like this is what happened with you, although i suppose you could also have picked up a wild yeast.

you could try spiking your berliner with some everclear. the boiling might have had other negative affects on the beer, but that would get you your alcohol back... or, you could revel in the knowledge that you might have the world's only alcohol-free berliner

that slurry now has both yeast and lacto in it, so plan accordingly. dunno how that combo is going to perform for fast souring (will the yeast be too fast?) but if you're up for an experiment why not give it a shot. if you do, let us know how it turns out. it would need to be a no-boil fast sour, or a post-boil sour - i would recommend the latter to kill off anything that might be alive in the wort.

 

[rmeskill]

Well I can definitively say the yeast wasn't too fast for my first batch-I was safely in the 3.8ph level when at 1.012, so I take it I would have gone down to more like 3.2 by the time the yeast finished up. I guess if we're fairly certain there's yeast in there already there's no sense to adding more except to try to beat out the lacto before it sours too much. At this rate I'm doing another one with the yeast/lacto slurry and don't plan on boiling to kill anything-I'll just let it go until it finishes and see how it ends up. I can always pasteurize them once they're in bottles if it comes to that. I'll keep everyone posted on how it goes.