big yeast cake floating in top of fermenter instead of falling out of suspension

[shuie]

I kegged two 5 gallon batches yesterday and had to deal with something a little out of the ordinary (for me, at least). There was a yeast cake was floating on top of all of the beer in the fermenter when I opened the lid. It actually looked like a sheet of of bread sitting on top of the beer in both batches.

On the brewday 3 weeks ago I used two packs each of dry S-04 and US-05 in the respective batches. These were not really big beers (~1.060 OG), so I over pitched. I did not rehydrate the yeast, just opened two packs of each and sprinkled the dry yeast in the fermenter after aerating the wort. I had good airlock activity in both batches almost immediately and the FG readings indicate the yeast did what it was supposed to. Pretty normal, except that it has always fallen out of suspension.

I'm guessing most of the yeast clumped together in the foam left on top of the wort from my aeration process (vigorous stirring w/slotted spoon). I always do this, but anyway. I did dump a fair amount of yeast from the bottom of my conicals before racking, so some of it fell out like normal. The beer that I racked off was as clear as normal, but the thick bread like layer of yeast floating on top of the beer really interfered with getting the last few pints out of each of the fermenters.

Is this normal? I've used both of these yeast strains a dozen times without rehydrating and have never had this happen before. The temps in my fermentation area have definitely been cooler over the last 3 weeks, but Im thinking the way I pitched the dry yeast onto the foam on the aerated wort was the cause.

Any thoughts on how to avoid this in the future? I guess I should start rehydrating my dry yeast again instead of just sprinkling it in the fermenter?

TIA

 

[Bensiff]

I've seen it happen a time or two. I give it a shake to knock it down loose, wait for it to settle at the bottom, then siphon.

I don't use dry yeast for fermenting just on occassion to assist in bottle conditioning, but everything I have ever read for using dry yeast (for brewing and other uses) is to properly rehydrate as it reduces the loss rate.

 

[aboule13]

Interesting, I pulled this thread up while looking for an explanation for a floating layer of yeast on an IPA I have in primary right now. I cant say my layer is "bread like" but there is definitely a thin yeasty layer.

Just to document this for posterity, I had a brain fart on this brew day. I had an ESB that I kegged while I was brewing my IPA. The ESB used the -04, and the IPA used the -05. What I did by accident was sanitize one carboy, and simply rinse out the one from the ESB. They both looked rather clean, but I did not sanitize the former ESB carboy. Of course I mixed them up and pitched right into the unsanitized ESB carboy.

We will see how it turns out, I wonder if the residue from the ESB yeast will contribute or lead to off flavors. I am not overly worried about contamination as I only washed the carboy out with water, and the ESB came out great

 

[aboule13]

Well, I gave the carboy a quick swirl and everything fell right to the bottom. It was about 2.5 weeks from brewday to today, so the layer struck me as kind of strange.