Samuel Smith's Yorkshire Squares

[McMullan]

It seems you are trying to have it both ways. If the process requires oxygenation, then it needs to reach the trough. So it's not that there is no O2 pickup, it's that the yeast and brewing processes are adapted to that O2 ingress and it is beneficial.

Have what both ways? O2 is usually required at pitching, depending on the pitching rate. Recirculating wort in a Yorkshire square is done periodically after active fermentation has started. The day after pitching, when the yeast head has risen high up in the trough. The need for O2 has passed at this stage. I have also experimented with a sealed yeast trough and get comparable beer, so I can't say I agree with this idea O2 is beneficial for the yeast after fermentation has started. Again, the primary reason for recirculating and spraying fermenting wort is to rouse the yeast.

 

[McMullan]

I'll leave it to the sciencey guys to explain that, but my point is that whether it happens early in the fermentation or not, spraying wort into the top chamber will result in O2 pickup and that O2 will reach the trough. We're in agreement that that does not produce oxidation in the beer. Because of their yeast and their capability of managing that process is Smith and others continue to use that process for their beer. On the other hand the LODO guys probably have nightmares about that sort of process.

Whether what happens early in the fermentation or not? I don't think you understand the process very well.

 

[DuncB]

For very high gravity ferments I've roused and supplied pure oxygen on day 2 and 3. No Oxidation problems due to the yeast actively metabolising to reproduce, or going about their usual business making ethanol and other products and probably metabolising any oxidised ingredients.
Any oxygenation during rousing in these open fermenters is not consequential.

 

[user 246304]

Just came on this and as I am eternally wanting to bring Yorkshire practice into my home as much as possible, I find it fascinating. It took me a long time to accept past my limited understanding and fairly rigid biases, that the system isn't about aeration. I "hand rouse" the first 48-72 hours (almost always now, closer to at most 60 hours), but @McMullan's system is something I still pine to achieve at home.

 

[user 246304]

By the way, it's a question I recently raised elsewhere, just curious - do these Yorkshire breweries following this practice oxygenate or aerate their worts prior to pitching - i.e., if the purpose of the recirc isn't about O2, do they oxygenate, or forego it, prior to beginning the fermentation?

 

[BrewZer]

No, the point of recirculating and spraying is to rouse yeast that have flocculated on the bottom of the yeast trough and FV below. They are highly flocculant yeast strains. O2 is only necessary at the beginning like a standard fermentation, unless enough healthy yeast have been pitched and oxygenating the wort serves no purpose. The info you are using is BS for the general public who know less about brewing than my dog.

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I might not know as much about brewing as your dog, but at least I haven't been neutered.