Ask Mr. Wizard

White Spots On Top of My Brew


Andreas Bettin - Toronto, Ontario asks,

I’m an extract brewer and I recently noticed a bunch of white spots on top of my brew (which was a wheat recipe) after I transferred it to the secondary. I thought it was mold forming but read that it’s probably “yeast rafts” or flocculated yeast clumps. The beer turned out nicely but I’m curious what causes this to happen? Are certain beer styles more susceptible to this phenomenon?

I am not completely sure about the nature of these little floaters. I think, however, that it is possibly either yeast, as you suggest, or protein clumps. Some yeast strains have a tendency to
Response by Ashton Lewis.