2nd pellicle on my lambic? Is this bad?

[Chris_J]

I made a beer a while back and pitched a pack of wyeast lambic blend. Within a little while I had a pellicle. It crusted over and all was right with the world. A while later it broke apart and sank to the bottom. It tasted pretty good actually. I was surprised by the amount of brett flavour. So I boiled the snot out of some oak cubes in a covered pot and then added them to the batch about two weeks ago. Today I noticed there is a thin film on top of the beer. Something else is at work here and I hope it's not a harmful (to the beer) bacteria or something ruining my beer. Is it uncommon for a lambic to restart fermenting? Maybe it wasn't completely done? Or should I just have a taste and refrigerate it to slow the bacteria and cut my losses?

[wezil]

2 things (or combination of the 2)
When you pulled the sample you disturbed the CO2 blanket and added oxygen. Which caused it to reform
When you added Oak you added and additional/more wild yeast (not real likley since you boiled them)

Brad

[Chris_J]

OK that makes sense. Will the extra oxygen cause some strain in the lambic blend to start fermenting again or is it just a protective layer? Thanks for your help, by the way.

[Bellmer]

OK that makes sense. Will the extra oxygen cause some strain in the lambic blend to start fermenting again or is it just a protective layer? Thanks for your help, by the way.

Double yes. It is a protective layer for a number of the strains that are in there, but it is also a fuel for some that are better left suppressed (like acetobactor...the minutest amount is ok but much more than the faintest hint ruins it - you got vinegar to drink).

[boobookittyfuk]

OK that makes sense. Will the extra oxygen cause some strain in the lambic blend to start fermenting again or is it just a protective layer? Thanks for your help, by the way.

Double yes. It is a protective layer for a number of the strains that are in there, but it is also a fuel for some that are better left suppressed (like acetobactor...the minutest amount is ok but much more than the faintest hint ruins it - you got vinegar to drink).

+1. vinegar is made commercially by adding oxygen and acetobactor to grain alcohol.

if you bump or move your carboy, you'll disturb the pellicule and it will fall down. After it falls, it can comeback it not disturbed. I tell my wife to not touch (or even look at) my sour beer carboys.

[Chris_J]

That's what I assumed as well. I guess I'll just have to taste it and go from there.