No Chill Keg Pressurization, small batch

[MattSFT]

I did a no chill brew today (dunkelweizen) by siphoning the wort immediately after the boil into a corny keg. I also put put the lid on immediately. The keg is still plenty hot at this time.

I brew 2.5 gallon batches, so there is oxygen in roughly half the keg. I wanted to pressurize the keg a bit to prevent negative pressure from cooling.

If I pressurize the keg with CO2, will I be pushing the oxygen in the headspace into the wort and subjecting it to hot side aeration? I've seen threads on 5 gallon batches, but not smaller ones.

I've heard HSA is somewhat of a myth, but I don't want to make assumptions. Does someone have knowledge/experience to share?

Thanks,
Matt

 

[Demus]

If you pull the release valve a few times the Co2 should displace the O2 because it's heavier. Are you planning to ferment in the keg?

 

[MattSFT]

Yeah, I was planning to ferment in the keg. I could transfer to another vessel for aeration if I need to purge the oxygen to pressurize.

I wonder if hot side aeration would be an issue if I pressurize as-is (oxygen still in the headspace)?

 

[Demus]

I think hot side aeration from a little headspace is the least of your concerns. No chill in a keg, you're gonna have all the cold break, trub, and spent yeast in the bottom of that keg. How are you planning to get all that out? How will the ferment off gas Co2? These are much bigger concerns than a little O2 in you're headspace as your wort cools. In fact, that brings up another issue. Once it finally cools, how will you get O2 INTO it for proper aeration?

 

[MattSFT]

Good points,

I'm not worried so much about the cold break, trub, and yeast since I always leave that stuff in. For letting off CO2, I'll be setting up a blowoff tube using the gas in post. There is a video online of a guy that does this, which is what got me interested in keg fermentation. I have an extra keg that I'll ultimately transfer the beer into for serving so that the sediment is left behind.

Your question on aeration is a good one and something that I hadn't thought about. I don't have an aeration pump, which would have come in handy for this method (putting this on my to-get list). Since I don't have a pump, I'll be transferring to another container for aeration. Very round-about, but I'll need to do this in this particular situation.

A large concern I had during the original post was damaging my keg as a result of the vacuum effect from cooling. It turned out that the keg held up fine, although the lid was nearly sucked into it when I went to check/relieve the vacuum.