Oxygen absorption

[hausofstrauss]

I did a few searches and I haven't found a discussion yet.

I'm wondering, has anyone ever actually done a scientific study to measure the differences in oxygen absorption between plastic and glass fermenters?

All this work to oxygenate the wort before fermentation and then to worry about oxygen getting into the beer seems ironic.

I see you can buy dissolved oxygen meters, but at $250+, I don't want to get one just for academic purposes.

I've got glass carboys, but buckets are just so much more convenient, easy to clean and you can install spigots. So I'd like to ferment and lager in plastic just due to my current setup. Should I dispense a small cloud of CO2 on top of the beer when I rack to the secondary?

 

[JJL]

In your example, the cause of oxygen penetration really doesn't have anything to do with glass vs. plastic. It's really an issue of sealing the vessel. Buckets have lids that don't necessarily seal very well. The carboy (glass or plastic) has a smaller opening that can be sealed with a rubber stopper or bung that creates a tighter seal than a bucket lid does. As for dispensing some CO2 over the top of the beer, you could, but it's probably not necessary. The beer is still producing small amounts of CO2 even after you rack it, so it will create its own blanket. If your using a bucket as a secondary, it won't matter if you use CO2 because it's just as likely to seap out as the beers naturally produced CO2.

 

[dcp27]

All this work to oxygenate the wort before fermentation and then to worry about oxygen getting into the beer seems ironic.

very different things. you oxygenate your wort for yeast reproduction. once this stage is passed, any oxygen added to your beer will oxidize it leading to stale/sherry/carboard flavors

In your example, the cause of oxygen penetration really doesn't have anything to do with glass vs. plastic. .... If your using a bucket as a secondary, it won't matter if you use CO2 because it's just as likely to seap out as the beers naturally produced CO2.

im sorry, but this is incorrect. its a very well known fact that plastic is worse for oxygen permeation than glass. also, when you rack, your beer should be done fermenting, so any released CO2 is what comes out of solution, not production. a bucket is a terrible secondary becuase it leaves far too much headspace

 

[TarheelBrew13]

I think JJL was referring to the op's example as having nothing to do with the permeability of Plastic versus glass to O2.

To the OP, if you want to know the difference between O2 permeability of plastic versus glass you can easily do a search for it. This type of data is frequently used by engineers to select materials. This, however, refers to how much oxygen you can expect to pass through the plastic or glass and not oxygen that would enter through the head space.

As for using plastic fermenters to lagger, this is certainly possible but as the previous poster mentioned your beer won't be producing much, if any, CO2 when you rack to this secondary vessel so that can cause problems. You could dispense a little CO2 to blanket the beer as you suggested. CO2 is much heavier than any other atmospheric element, especially O2, so the CO2 would not be in danger of floating away unless it was somehow disturbed.

 

[hausofstrauss]

So to clarify my question, does anyone have any actual empirical data to show just how much beer gets oxygenated by sitting in a plastic bucket after the fermentation process is complete?

If the lid is the biggest leak, then theoretically placing a layer of CO2 over the top of the beer would shield against oxygen. This would also negate arguments against too much head space.

I 100% agree that plastic is permeable and that stainless is better. It would just be a very interesting comparison if someone was fermenting two beers. One in glass and one in plastic. Taking samples over time to see what the measured difference is.

Most importantly, has anyone been able to detect a taste difference between an 8 week lager done in plastic versus stainless or glass? Of course assuming best practices in both cases.

 

[JJL]

You might get something out of this thread.

https://www.homebrewtalk.com/f163/oxygen-permeability-plastic-298055/

And yes I was talking about the OP's example. I was really talking more about head space and CO2 leaking out allowing the beer to be less protected from O2. I'm not arguing the technical aspects of the O2 permeability of glass vs. plastic. I would argue the practical impact of the O2 permeability for homebrewing, but that's more of a subjective argument.

 

[hausofstrauss]

You might get something out of this thread.

https://www.homebrewtalk.com/f163/oxygen-permeability-plastic-298055/

And yes I was talking about the OP's example. I was really talking more about head space and CO2 leaking out allowing the beer to be less protected from O2. I'm not arguing the technical aspects of the O2 permeability of glass vs. plastic. I would argue the practical impact of the O2 permeability for homebrewing, but that's more of a subjective argument.

Thanks for the link to that thread. I don't know why I didn't find it before. So I guess it answers my question. There still doesn't appear to be anyone who has done a legitimate test showing O2 absorption in to beer over time.

What I get from that thread is that whatever amount of O2 that seeps into the beer is completely dwarfed by the amount introduced from racking.