Headspace question

[Joewalla88]

I'm curious about the headspace on this half batch berliner I've got going. It's just in primary, and I'm bottling it this weekend, but I opened it up to sample it to see if it was. Am I good? I know you don't want a lot of headspace in secondary, but I'm wondering if letting air in to sample is an issue.

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[GoeHaarden]

CO2 is heavier than atmospheric air, so it will stay relatively settled if you were gentle getting your sample out. Since your yeast produce CO2 there will be a natural layer in your primary. Just have to find the balance between head space and room for fermentation. But all-in-all you should be fine...

 

[Joewalla88]

Cool, thanks. I usually just leave my beer alone tills it's done, so I wasn't sure about this one.

 

[doug293cz]

CO2 is heavier than atmospheric air, so it will stay relatively settled if you were gentle getting your sample out. Since your yeast produce CO2 there will be a natural layer in your primary. Just have to find the balance between head space and room for fermentation. But all-in-all you should be fine...

CO2 is heavier than air (44 vs 32 for O2 and 28 for N2), but it does not "stay settled." Gases spontaneously interdiffuse in a matter of minutes, and taking your sample had to create some disturbance which would speed mixing of air and the CO2 in the headspace. Active fermentation will push air out of the headspace very effectively, but when fermentation slows, air ingress becomes more of a problem.

Best practice is to minimize sampling after fermentation slows down.

All that said, lots of folks have been making beer without always using best practices to avoid O2 post fermentation. Unless you are making a style that is particularly sensitive to oxidation (such as an IPA) you will probably ok.

Brew on

 

[GoeHaarden]

... "stay settled"...

Forgot the " relatively" in the middle there

 

[Joewalla88]

I'm hopefully bottling this tomorrow, so I'm thinking it'll be okay. I've just seen some nasty infections from people leaving too much headspace, but I dont think it'll be an issue here. Thanks for the reassurance.

 

[GoeHaarden]

I don't think there is a correlation between headspace and infection...but I'm sure someone has a scientific theory to dispute me. Blah blah blah.