I have been fermenting my sour beer for two months now. I pitched dregs from Bam Biere Jolly Pumpkin along with another belgian yeast. I tasted and measured my beer a month ago and it tasted good, but could become more tart. The reading was at 1.010. Everything seemed good, and now it has a thin white film on top. I am about to taste and measure it again. Does anybody know if the film is normal or is this a bad sign? I have heard of beers being made from pitching dregs that start off great and age poorly because of other little microorganisms that eventually take over. Any ideas?
It’s normal for a pellicle to form with certain kinds of souring microorganisms. I wouldn’t worry about it. RDWHAHB.
That’s the Wild Yeast (Brettanomyces) in action. They usually form a white film (pellicle) on top of the beer during secondary fermentation. If you have an airlock attached to the fermenter, it won’t produce much acetic acid (tartness) due to the lack of a aerobic (oxygen) free environment. The white pellicle will not harm your beer whatsoever. When it comes time to racking (preferably 6-8 months into secondary), just puncture a hole through the film and start siphoning. ;D
The white film is also an O2 barrier (of sorts), and Vinnie Cilurzo has said he does not disturb it. Has his barrels set up with SS nails that he can pull out for a sample, drawing from underneath the pellicle.
I still use an airlock for my sours, but they are in a barrel, getting small amounts of O2.
That is where my beer wound up as well…I have the nails to use if I desire, but just cannot seem
to make myself put a nail hole in my oak cask…Airlocks have not moved much in a few weeks now…
Seems they resemble thermo/manometers more than airlocks now…liquid level moves when the
ambient temp changes…or when atmospheric pressure changes…I cannot help but wonder how much
they might be inhaleing now and then as a few small inequalities allow air bubbles to pass in the airlocks.
Edit: back on topic, your beer is prolly a-ok