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white 'crust/scum/stuff' on top of fermenting batches in car

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Post Wed Jun 11, 2008 7:13 pm

white 'crust/scum/stuff' on top of fermenting batches in car

Last year we had a blood orange mead that got stuck [too much acid for the yeast from the insane amount of oranges i squeezed into the must] and I kept it in the carboy for about 9 months, even once it was obvious it was dead [but the flavor was such that everyone with a sweet tooth loved it and so we did not re-start it, and just bottle it as a dessert mead and give it to various folks as gifts ;)]. Anyway before bottling I noticed there was some white crust/scum/whatever in the top of this, and if I shook it up it 'broke' apart. There was only a bit and so I didnt worry about it and went on with life.

This year three of our batches have this stuff, more than the blood orange.

The one that has the most is actually a wine with no honey in it.

Should I be worried about this?

Anyone else run across this?

If they were not in carboys I'd just skim it off, but I dunno if I rack it if it will just reform or somehow escape into the new carboy...bleh.

Thoughts? experiences?



Brew-r Tom


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Post Wed Jun 11, 2008 7:30 pm

Without pictures, it sounds like acetobacter infection. I had it happen once because of fruit flies.


Post Wed Jun 11, 2008 9:18 pm

hmmm, what does it do exactly and what does one do about it? [and also how to prevent it....we use vodka in the vapor locks...]


Post Wed Jun 11, 2008 9:55 pm

Strongly disagree with Tom's diagnosis. Saying it's acetobacter just because there's white stuff is...premature to say the least. Acetobacter exhibits as a cloudiness in the brew, with an oily, matte film on top, and a strong odor of acetone or vinegar.

I've seen ciders or beers, after 4+ weeks in primary, develop a thin layer of white stuff that I am fairly sure is yeast, floating at the top. There is no off-flavor or odor and no mold, and is, far as I can tell, harmless.


Post Thu Jun 12, 2008 3:58 am

Well, I examined one of them last night [one that had not been shaken to disturb its forming] after slightly panicking and noticed a definite structure to it, like a living bacteria, but it was not any kind of yeast structure I've seen before. Generally yeast seem off white to orangey brown and just appear fluffy/fuzzy in various colony/cloudy shapes. And do not live on the surface. I wish I had taken pictures, but well my camera battery was out of charge.
This had long thin structures/formations with knobby ends.
I racked the two with the worst of this, trying to be careful to not get the white stuff [which breaks apart into tiny white flecks when shaken at all] into the 'new' batch, sterilized the hell out of the equipment with b brite solution, and added more yeast and a bit of sugar.
Both batches are very very young and so tasting it, I'm not sure if they are truly on track and young or something is off. Both tasted a bit flat/thin/bit sour. Going out of town in 15 minutes for about 5 days, and hoping to come home to find this done. The 3rd had such a light infestation [and it was so 1AM] that I left it and may rack it when I return...
*crosses fingers hopefully*


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Master Brewer

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Post Thu Jun 12, 2008 5:16 am

Can't say for sure but I have seen a whiteish surface layer on my heavier beers out of the primary. It seems to adhere to itself but still not enough of it to cover the whole surface.

Don't know why it was white but since it floated I figured it was some oils that where released from emulsion and collected some impurities from the crap on the bottom of the fermentor.

Didn't seem to effect the taste and no one ever got sick.


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Post Thu Jun 12, 2008 6:24 am

Without at least a good picture to look at it's impossible to take an educated guess on what it is. It's either trub, yeast, or an infection that you're describing. My guess right now is it's infected, post a picture when you get a chance.
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