Burton continuing to go bad.

If it were me, the second it was funky/sour it would be dumped.

IF you like why not let it ride and have something fancy/wild going? You might not be able to make it again, but at least what you have you would enjoy.

 

The fact that you have a pellicle is telling. Mostly that there is a species of microbe in your fermenter that is a biofilm former. Many are.

As an aside, nobody should want a pellicle on their beer. It is a sign of oxygen ingress and beer does not like oxygen.

Unless you are up for a completely unknown end product, I'd dump it. How does it smell? Have you tasted it?

 

Oh, I'm sure that you have and they were, but they shouldn't be. Pellicles/biofilms are a response to oxygen, not a protection from it. They are decidedly not a good sign.

 

I would taste it...probably not something you want to keep,,,but it will either get better or worse with time.

"While seeing something like this on the surface of a normal homebrew would be a cause for alarm, it is perfectly normal when going through a wild fermentation. The film is called a pellicle and it's a basic defense mechanism of both Brett and Pedio, protecting the bugs in the beer from exposure to air and bacteria." Joe Postma

 

This is, very irritatingly, one of the most well held onto myths in homebrewing.

Pellicles DO NOT protect a beer from oxidation and are made by most non-domesticated species of bacteria and yeast. Modern saccharomyces cerevisiae strains have simply been selected in such a way that the gene for pellicle formation has been turned off. If you see a biofilm on your beer, be assured that it is getting more than a micro amount of oxygenation.

 

I was under the impression that it depends on which pellicle is present first...acetobacter being the one that uses the most oxygen (completely aerobic) and that the pellicles from Brett and Pedio can help reduce acetobacter infections.

http://www.beersnobs.org/recipes_tools/SourPresentation.pdf

 

HOLY FUCK is that presentation full of errors. Some decent information mixed in there, too, but mostly just errors. Where did you get that?

 

Examples?
Didn't check his sources, I have Sparrow's book (WildBrews)...but was lazy
Edit: pg. 109

 

To answer your question more directly, it doesn't matter which pellicle is present first. Mostly because more than one microbe can aid in the formation of a single biofilm. Secondly, you can't have an acetobacter infection if you don't have a lot of oxygen, as most acetic acid forming bacteria are obligate aerobes. Thirdly, although Brettanomyces sp. and Pediococcus sp. certainly can form pellicles, so can Lactobacillus sp., Saccharomyces sp., and other yeast and bacterial species from other genera. Fourthly, once you have acetic acid in your beer at high levels, the only thing that you can hope for is esterification to ethyl acetate by Brettanomyces sp., which can not only form acetic acid, but have strong enough esterase enzymes to make ethyl esters from it, like ethyl acetate. Even then, you're better off just dumping your beer, because either of those chemicals at high levels are unpleasant and irreversible.

 

Do you want me to list them numerically (by page number) or alphabetically?

 

No, that's ok...I almost didn't post it until I saw Sparrow's citation: "Brettanomyces exhibits the odd propensity to form a pellicle- an often thick, lumpy white coating -on top of liquid during fermentation. The yeast cells form chains that can float on the top of the wort, making use of atmospheric oxygen, characterizing Brettanomyces as an oxidative yeast. The pellicle will form in the fermenting vessel or even in the bottle if the Brettanomyces sp. still have a source of sugar to ferment. The pellicle helps to guard against oxidation during a long fermentation process, as well as against unwanted mold and Acetobacteria, so should be left intact."

 

While I certainly respect Jeff and Wild Brews, he's not a microbiologist. I'll take their word over his any day.

Pellicle formation is only odd if you look at modern, well-selected Saccharomyces cerevisiae strains used in brewing and wine making. In the rest of the microbial world, they are normal at air-fluid interfaces.

Pellicle formation is decidedly NOT why Brettanomyces is characterized as oxidative. It is because the genera both grows and ferments better in the presence of oxygen, which is the opposite of Saccharomyces sp. Also see Pasteur Effect vs. Custers Effect.

Again, this is not why pellicles form. If there is still fermentable sugar in solution, but no oxygen, Brett., or any other yeast or bacteria, will not form a pellicle.

A pellicle does not protect the beer from anything. It is simply a vehicle for the microbes to use oxygen. Since the vast majority of molds and acetic acid forming bacteria are obligate aerobes, the carbon dioxide produced by the microbes in solution will protect the beer just fine.

 

BTW, sorry if I've gotten this thread off on a tangent, but I think this stuff is important enough to correct errors and myths.

 

You probably need to correct Michael Tonsmeire (American Sour Beers) also...pg 252

 

I like Mike. He's a good dude who is very generous with his time and has done a lot for the sour beer brewing community at large.

However, he's also not a microbiologist or a chemist. His excellent blog and ASB have some obvious technical errors, but are otherwise wonderful source material that I often use myself.

 

Keeping in mind that I believe ASB to be a very good book, the two sources that I most often refer to are the Milk the Funk wiki (pellicle page), each page of which is thoroughly cited, and Dr. Matt Miller's excellent blog called Sour Beer Blog.

There are certainly copious amounts of other materials, but I find those two to be the easiest to read and the most complete.

 

Did he say that?

I would be glad to hear what a microbiologist or chemist has to say on disturbing pellicles in...say a lambic or wild brew
Nice discussion, but yes, we are off on a tangent...sorry to OP