Breweries that counter-pressure fill

I really don't understand how there can be any advantage to purging a growler with CO2 before filling. They are filled to the absolute max anyways. This pushes all air out of the growler.

 

I have sometimes found this not to the case. I've seen some filled an inch and a half below the rim. That's not the norm, but it has happened enough.

 

Berryessa Brewing does counter-pressure filling.

 

The idea is that the beer is getting less oxidized during the filling process. When you purge with Co2 the beer is coming into contact with less oxygen as the growler is being filled. It's about more than just the headspace.

 

Doesn't the head build up in the growler act as a layer of protection during the fill? The foamy head always gets pushed out leaving the beer untouched to ambient air.

I think you guys are really splitting hairs, and i believe CO2 purge is most likely unnecessary.

 

Sierra Nevada Torpedo Room has a counter fill setup. It's like buying a packaged beer. Purged and ready for now or later.

 

But the dank sauce...

 

You're pouring beer into a container full of oxygen or a container full of Co2. They're clearly different, but to what degree I cannot say.

 

Gaseous diffusion, atmospheric pressure, container with a 1/4 opening to widest diameter ratio (more or less).

I used to know how to calculate this problem. But in essence, if they flush the container enough, it's not going to leak all that much before filling. The air up top will be almost all CO2 if they purge.b

The real issue is how much that little head room of air (20% oxygen at that) is responsible for beer degradation. I'd argue very little - the real problem with bombers is unsealed caps, not the little bit of oxygen if they don't purge.

 

I opened a Bruery growler of SITR w/ Boysenberries (from last September!) this past weekend and it was completely carbonated and tasted great. I didn't mean to save it that long (it got buried in the back of my fridge and I forgot about it), and when I opened it I was worried that the fruit flavor would have fallen off - I guess it's possible that it wasn't as boysenberry-forward as it would have been fresh, but the boysenberry was very prominent and it was delicious. I don't think they counter pressure fill though, so I guess I just got lucky.