Mold or Infection?

What went wrong? Was this supposed to happen? Should I throw it out? What do I do now?

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Mold or Infection?

Postby Suthrncomfrt1884 » Wed Aug 19, 2009 10:07 pm

So, my latest batch (an oktoberfest) was done fermenting a few weeks ago, but I decided to leave it in primary for a total of 26 days. I went to keg it today and when I pulled off the lid, I noticed there was a whiteish glass-like substance floating on top with the remnants of the krausen that hadn't fallen in. It had bubbles formed in it, and when I went to skim it off, it broke apart like plasic.

I'm not too concerned about the beer, just wondering if anyone can tell me what happened? After tasting the beer, it has a little bit of a sour flavor, but not enough to ruin the beer. It still tasted fine.

The yeast used was wyeast california lager. I didn't make a starter so it tok about 36 hours for fermentation to start and it fermented at the high scale around 67 degrees the whole time.
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Sounds like start of acetobacter

Postby billvelek » Thu Aug 20, 2009 11:05 am

Two things you said suggest the very early stage of an acetobacter infection: sour taste and a glass-like or plastic-like film on top -- although I don't know how accurate "plastic" is as a description; I assume the thin film will be transparent like glass while it is still very thin. Acetobacter is a bacteria which converts alcohol into acetic acid and IIRC cellulose or something very similar to it; it is how wine spoils. The acetic acid causes the sourness and the cellulose like substance collects as a membrane on top which will actually get quite thick like a pancake as the process continues. This is how vinegar can be made, and I believe the celluose membrane is referred to as 'mother of vinegar'. I am familiar with the process because I used to make kumbucha tea (also known as mushroom tea, although the floating pancake is not a mushroom). I don't know how the process can be stopped other than finding a way to kill all of the bacteria, possibly by heating your beer at least to pasteurizing temperature -- which is probably going to be very close or above the boiling point for ethanol, so you ought to keep the container tightly covered and not heat for too long in order to prevent too much loss of alcohol. I also don't know if all acetobacters are the same in the sense of how much acetic acid they can tolerate; for instance, lambic beers are deliberately infected to cause their sourness. I've never made one, so I don't know if it is a natural process for the acetobacters to stop at a certain point before the beer gets too sour -- possibly dependent on the strain -- or if steps are taken to kill them. Unless someone here knows, you will need to do a bit of research on these issues. Obviously, if you do kill off the bacteria, you will be killing the yeast, too, so you will need to pitch some new yeast into your starter solution before bottling.

Good luck.

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Postby Suthrncomfrt1884 » Thu Aug 20, 2009 3:18 pm

This concerns me. I had originally thought it was a bacteria strain that takes hold in lambics, but wasn't sure how a lambic style oktoberfest would taste, so I kegged it anyway.

I'm thinking the culprit has to be my plastic buckets. This one hasn't been replaced in awhile. My sanitation is always very strict, so I doubt it could have been that. The only thing that changed was the lager style yeast fermented at higher temps and the length of time I left it on the yeast.

I will definately be doing to research to see if I can save the batch. Hopefully when it comes time to carbonate it, it will taste fine.
Primary - Belgian Dubbel, Belgian IPA
Secondary - Cherry Lambic
Bottled - Bourbon Barrel Coffee Porter, Double Chocolate Raspberry Stout, Imperial Nut Brown, Apfelwein, American Amber Ale w/Homegrown Hops, Breakfast Stout
Kegged - Bass Clone, ESB
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bacteria

Postby slothrob » Thu Aug 20, 2009 5:06 pm

I wouldn't worry too prematurely. I had an Oatmeal Stout that had a similar looking infection, kind of a clear, oil-like film on the top. I bottled the beer and there was a slight sourness. Whatever it was, I held bottles of that beer for a year and a half and it only got better. The sourness never progressed much beyond what I tasted at bottling and integrated into the beer's overall flavor after a couple months. The beer was great and it must not have been acetobacter.

My buddy had fruit flies get to his beer and he got an acetobacter infection and the beer got very sour and he dumped it.

I'd wait it out and hope for my bacteria not his.
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Postby Suthrncomfrt1884 » Thu Aug 20, 2009 5:39 pm

Here's a picture if it helps. It's a bad picture because of all the krausen that didn't fall in, but you can see the white stuff on the right side.

Image
Primary - Belgian Dubbel, Belgian IPA
Secondary - Cherry Lambic
Bottled - Bourbon Barrel Coffee Porter, Double Chocolate Raspberry Stout, Imperial Nut Brown, Apfelwein, American Amber Ale w/Homegrown Hops, Breakfast Stout
Kegged - Bass Clone, ESB
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That doesn't look like what I meant

Postby billvelek » Thu Aug 20, 2009 11:16 pm

I've never had an acetobacter infection, so I'm not _positive_ what it's supposed to look like, but I believe that it should be fairly uniform across the surface. Your photo doesn't look like that, but maybe it's just from stirring. Anyway, you know what it looked like before, so I'd suggest that you look at these pictures on the following websites and maybe some others on Google Images:

I don't know the language, but the photos are typical of my kombucha tea:
http://www.houby-tibet.estranky.cz/clan ... cha-obecne

http://blog.craftzine.com/archive/2007/ ... F307375954

While looking for some info for you, I came across this website that indicates that ozone can be used to fight bacterial infections when making wine, ... so why not with beer, too? http://www.mcclainozone.com/wine.html

Hope that helps.

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