Yeast+trub cake blew up while racking

[Justy]

Hi, everyone.

A weird thing happened while I was bottling the last batch of my double IPA today. I don't rack to secondary (tried it, made no perceptible difference, didn't adopt it). Was racking from the fermentor into a bottling bucket, and when I was about 2/3 through, a crazy amount of bubbles went up from the bottom of the bucket, breaking up the yeast cake and hop trub on top of it. The piece of sanitized pantyhose I use for filtering spared me the worst of it, but I still ended up with lots of extra yeast and some fine hop powder in the bottling bucket.

Any ideas on what might have caused it? Any ideas on how to prevent it from happening in the future? I'm absolutely sure I haven't touched the surface of the cake (the racking cane never even went close to it before it blew up). It looked like the gas was trapped somewhere in the cake, or like a lot of CO2 somehow decided to come out of solution at once.

 

[bucketnative]

Were you siphoning out of a previously cold-crashed fermentor? If yes, then it was likely a release of CO2 as the contents warmed up and CO2 started to come out of solution. It may be that once you got 2/3 of the beer off the cake, the pressure of the "beer column" was about equal to that of the CO2 that had come out of solution and remained trapped in the trub. Hence the seemingly sudden onset of the issue.

At least that's my best guess.

 

[Justy]

No, the bucket had a constant temperature since the moment I pitched. But I think with the ~7 gallons or so on top of the cake, it may just be possible that the pressure drop itself caused a lot of the dissolved CO2 to come out of solution at once. Or is that too far-fetched?

 

[greeze]

I`ve had that exact thing happen to me recently. the two carboys were pulled from the ferementor and sat on the bench. While siphoning the somewhat cold crashed beer (55*) at about half way the cake just expelled hop and trub into suspension, I thought the cane had fell into the trub. I went on tot he next one to complete the keg fill and just like the first it let loose about halfway but the can was no where near the cake.

first time I`ve seen it and I`ve been brewing over 3 years. it was a ipa using wlp090

 

[Justy]

Good to know I'm not insane. So, any way to prevent it from happening in the future, other than reducing the batch size?
Using a bag for the dryhop, perhaps? I'm not too sure about the mechanics of that, and I like to keep the interference to a minimum, but on the other hand it might also allow me to use the spigot before bottling, because the yeast cake usually doesn't reach the spigot hole by itself (i.e. without another inch of hop trub on top of it).