The pellicle photo collection thread on HBT is full of pictures of how infected beer often appears.
https://www.homebrewtalk.com/threads/pellicle-photo-collection.174033/Granted, most of these are intentionally pitched with bactera and/or brett to make mixed fermentation beers; however, beers unintentionally infected with bacteria and wild yeast often create these same biofilms.
You may see cloudiness before, during, or instead of a biofilm. That's often a sign of infection, too. Wild yeast can do some weird things like make what looks like mushroom caps floating on the surface or spongy blobs that sort of look like flattened silly putty. If you see what looks like a disc or fried egg floating beneath the surface, that's either acetobacter or a combination of acetobacter and other contaminates forming a combined mass, similar to a scoby used to ferment kombucha.
Mold like you think is fairly uncommon in beer. You can get mold growth if you add fruit or other ingredients in secondary that float. If wort fails to start fermenting in a few days, you can also see mold growth. In these cases, it may be fuzzy, powdery, or furry growth like you see on bread. It may also be fairly smooth blobs of unusual colors like red, blue, yellow, or green. Mold will either float on the surface or grow along the edge of the surface and up the side of the vessel. If unexpected growth on the surface is white or tan, it's most likely yeast and/or bacteria. Any other color, likely mold.
Topic: beer contamintaion (Read 6571 times)
