Contamination Options

[WillRun4Beer]

i recently brewed a scottish ale. i left it in the primary for about 5 weeks then racked it to a secordary glass carboy for clarification. a couple of days after racking, i started noticing these little white floating discs on the surface of the beer, some of which actually seem to have a hexagonal shape. the FG was in my target range and the beer did not smell off when i racked it. should i be worried about these discs? could it be mold, and if so, will it harm the beer?

[Dave F]

i recently brewed a scottish ale. i left it in the primary for about 5 weeks then racked it to a secordary glass carboy for clarification. a couple of days after racking, i started noticing these little white floating discs on the surface of the beer, some of which actually seem to have a hexagonal shape. the FG was in my target range and the beer did not smell off when i racked it. should i be worried about these discs? could it be mold, and if so, will it harm the beer?

Could you post a picture? I suppose it could be a mold, but could it be some sort of foam? Other yeasts like Brettanomyces can form pellicles that would float on the top too...
Perhaps you could scoop one out with a sterile implement and look at it magnified...

[WillRun4Beer]

Could you post a picture? I suppose it could be a mold, but could it be some sort of foam? Other yeasts like Brettanomyces can form pellicles that would float on the top too...
Perhaps you could scoop one out with a sterile implement and look at it magnified...

a couple of them appear to be bubbles but the rest look fuzzy and are hexagon shaped. weird. i'm gonna try to bottle it tonight, if it tastes ok. Here's a pic, i think. it's not very good. i only have a camera phone, and not a very good one at that. Any input would be appreciated.
(IMG:http://www.uscconlinealbum.com/photos/photo01/54/5c/8e4a18b5fa17.jpg)

[Slainte]

It could be mold or a pellicle forming from wild yeast or bacteria. Chances are it's not a good thing. Brewer's yeast doesn't rise and float to the top when fermentation is complete. Chances are you introduced some oxygen upon transferring the beer, and nothing will get a pellicle up there faster than O2.

Did you taste it at all? You say you smelled it, but that probably wouldn't tell you much. Especially since it wasn't carbonated.

I would let it sit some, monitoring the gravity over time, and tasting it. If it keeps dropping, something is munching on it other than Saccharomyces. You don't want to bottle it and risk gushers or worse, exploding bottles. If you don't want to wait, you could do a test. Bottle one in really thick glass, and set it in a warm location for a few weeks. The warm temperature will accelerate microbial activity.

Most importantly, you want to closely examine your cleaning and sanitation practices. Replace all plastic, and use a no-rinse sanitizer. StarSan or Iodophor works best for that. Clean and sanitize in two steps. You can't sanitize a dirty surface.

edit: Just saw you posted a pic. Impossible for anyone to draw any conclusions...it's too fuzzy. The fact that you see some bubbles (those are fine), but also some fuzzy stuff (bad), makes me think you have a problem.

This post has been edited by Slainte: Nov 19 2009, 06:26 PM

[WillRun4Beer]

It could be mold or a pellicle forming from wild yeast or bacteria. Chances are it's not a good thing. Brewer's yeast doesn't rise and float to the top when fermentation is complete. Chances are you introduced some oxygen upon transferring the beer, and nothing will get a pellicle up there faster than O2.

Did you taste it at all? You say you smelled it, but that probably wouldn't tell you much. Especially since it wasn't carbonated.

I would let it sit some, monitoring the gravity over time, and tasting it. If it keeps dropping, something is munching on it other than Saccharomyces. You don't want to bottle it and risk gushers or worse, exploding bottles. If you don't want to wait, you could do a test. Bottle one in really thick glass, and set it in a warm location for a few weeks. The warm temperature will accelerate microbial activity.

Most importantly, you want to closely examine your cleaning and sanitation practices. Replace all plastic, and use a no-rinse sanitizer. StarSan or Iodophor works best for that. Clean and sanitize in two steps. You can't sanitize a dirty surface.

edit: Just saw you posted a pic. Impossible for anyone to draw any conclusions...it's too fuzzy. The fact that you see some bubbles (those are fine), but also some fuzzy stuff (bad), makes me think you have a problem.

well, i just moved it into my kitchen and the formations seemed to break up. after closer examination, they appear to be extremely fine bubbles. if it was mold pellicles, i wouldn't expect them to break up. any thoughts?

[Slainte]

In my experience from brewing sour beers, pellicles break up very easily when rousing the fermenter, and can vary in appearance.

Although if they look just like "normal" bubbles to you...well you're the one that can see the beer. (IMG:style_emoticons/brewboard/smile.gif)

But taste it and monitor the gravity to be sure.

This post has been edited by Slainte: Nov 19 2009, 07:38 PM

[WillRun4Beer]

In my experience from brewing sour beers, pellicles break up very easily when rousing the fermenter, and can vary in appearance.

Although if they look just like "normal" bubbles to you...well you're the one that can see the beer. (IMG:style_emoticons/brewboard/smile.gif)

But taste it and monitor the gravity to be sure.

yeah, i tasted it and took a gravity reading. tasted ok. high alcohol content. no obvious off flavors. gravity was same as a week ago when i moved it to the secondary. they definitely appear to be fine bubbles. wouldn't mold be sort of fuzzy? i'm gonna go ahead and bottle it and monitor.

[slothrob]

I see that your secondary has a lot of head space above the beer. That's not recommended, you should get a bottle that is nearly full, if you are going to secondary, or skip the secondary.

The reason I bring this up is that beer is often contaminated to some degree and one of those contaminating organisms can often be acetobacter. The yeast pitched will often out compete those organisms, lower the pH enough to inhibit them, or use up the oxygen and prevent it from growing. If you add back oxygen, from a rough transfer or from a large headspace in secondary, acetobacter can start to grow until the oxygen is used up. The good news is that if it is acetobacter, it shouldn't grow once the beer is bottled.

Just watch for over carbonation in the bottles, in case it is a wild yeast that can ferment sugars that your pitched yeast can't.