Headspace

[Thanks_Yeasties]

I have a sour going in a 15 gallon demi-john with about 2 gallons of headspace. I hooked it up to a 6 foot long blow off tube that ends in a pitcher of starsan. Being that it is still in the primary, undisturbed since fermentation started, would there be any worry that some of that headspace is exposing the beer to oxygen?

Seems like even with temp change in suck back, no outside air/starsan will ever make it all the way back up the blow off tube and the headspace would be filled with CO2 from fermentation still.

Any thoughts?

 

[Oldsock]

It'll be fine assuming the blow-off is tightly fit and the end stays submerged. Head space is a much bigger issue in barrels because it allows the wood near the top to dry out (becoming more permeable). In impermeable fermentors, the issue is just that each time you open it up for a sample, more air can get in. 5-10% is no big issue, just don't go pulling samples once a week!

 

[Thanks_Yeasties]

Thats what I was thinking, sounds like I have nothing to worry about then.

Hopefully one day soon I will have barrels of worries!

 

[millsbrew]

Reviving this old thread since I have a similar question. My issue is the opposite. I had close to 6g in the fermenter. Racked to secondary, and got all the way up to the neck of the 5G glass carboy. Is there a pro/con to leaving such a small amount of head space?

 

[EPbrew]

Reviving this old thread since I have a similar question. My issue is the opposite. I had close to 6g in the fermenter. Racked to secondary, and got all the way up to the neck of the 5G glass carboy. Is there a pro/con to leaving such a small amount of head space?

Not enough headspace is a problem in primary but shouldn't be in your secondary. Did you need to use your primary for something else? There's really no reason to transfer to secondary unless you're aging it for more than a couple months IME.

 

[millsbrew]

Thanks. I did not "need" it, but will be filling the fermenter next weekend. I will be aging my sours at least 8 months, probably closer to a year. I want to increase sourness, so I thought transferring off the sac yeast cake would give the brett less to eat, and give the bacteria a chance to eat some of the residual sugars/carbs. From my limited research, funk character increases if it is left on the sac yeast for too long. Is that not the case?

 

[EPbrew]

I'm pretty new to sours so I don't know how to answer your question and be 100% correct. I would suggest picking up "American Sour Beers" if you haven't already. I am about half way through and it's very informative. You also might find the answer here: www.themadfermentationist.com

 

[millsbrew]

Read it. Seems most commercial breweries rack after primary but I'm guessing that has to do with space/production requirements. I will just wait it out. Thanks.

 

[TAK]

I think leaving it on the original yeast cake from primary can lead to increased funk character, most likely from autolysis, or autolysis-like processes, which would be completely undesirable in a clean beer, but can be interesting in a sour beer, where Brett is more daft in how it autolyzes (is that a word).

Millsbrew, to your original question, I think for aging in glass, minimal headspace is best practice. I have 3 soleras that I keep filled to 1-2 inches from the bottom of the stopper.

 

[millsbrew]

Thanks TAK. I did some more reading and that seems to be the norm since sampling will reduce quantity and increase headspace over time. Appreciate it.