Samuel Smith's Yorkshire Squares

[Bob C.]

I have a question. How does SS ferment using their open Yorkshire Squares when oxygen is so detrimental to quality beer.

 

[rmr9]

I have a question. How does SS ferment using their open Yorkshire Squares when oxygen is so detrimental to quality beer.

The yeast they use forms a massively thick krausen that protects the beer under it. Once the fermentation slows they package it up so exposure to oxygen is limited.

 

[rmr9]

Limited oxygen exposure without active yeast I should say

 

[eshea3]

If the beer is going in cask, it will be racked to cask where additional fermentation will take place which should scavenge residual O2. Once in cask, it is out to the trade and dispensed in a relatively short period of time. Once the cask is tapped, there will be oxygen ingress in any event and that is part of the real ale process and profile.

 

[McMullan]

A Yorkshire square is actually a closed fermenter, strictly speaking. The vessel on top of the fermenter, the yeast trough, is essentially a big ‘airlock’. Oxidation of the fermenting beer just isn’t the problem it might seem. Even in the more commonly used open squares in England and elsewhere, oxidation just isn’t a problem, if the brewer knows what he or she is doing. I’ve had commercial bottles of beer fermented in these systems stored in the fridge for over a year without noticing any detrimental oxidation developing. Nor have I noticed any problems with the ales fermented in my Yorkshire square, but they’re usually consumed within a month or few at most.

 

[rmr9]

A Yorkshire square is actually a closed fermenter, strictly speaking. The vessel on top of the fermenter, the yeast trough, is essentially a big ‘airlock’. Oxidation of the fermenting beer just isn’t the problem it might seem. Even in the more commonly used open squares in England and elsewhere, oxidation just isn’t a problem, if the brewer knows what he or she is doing. I’ve had commercial bottles of beer fermented in these systems stored in the fridge for over a year without noticing any detrimental oxidation developing. Nor have I noticed any problems with the ales fermented in my Yorkshire square, but they’re usually consumed within a month or few at most.

I think I’ve seen pictures of your Yorkshire square on other threads and it was super cool

 

[eshea3]

A Yorkshire square is actually a closed fermenter, strictly speaking. The vessel on top of the fermenter, the yeast trough, is essentially a big ‘airlock’. Oxidation of the fermenting beer just isn’t the problem it might seem. Even in the more commonly used open squares in England and elsewhere, oxidation just isn’t a problem, if the brewer knows what he or she is doing. I’ve had commercial bottles of beer fermented in these systems stored in the fridge for over a year without noticing any detrimental oxidation developing. Nor have I noticed any problems with the ales fermented in my Yorkshire square, but they’re usually consumed within a month or few at most.

By strictly speaking I take it you mean the actual vessel in which the wort is fermenting. Am I corrected my understanding that the upper deck where the yeast is discharged is open to the atmosphere?

 

[McMullan]

Am I corrected my understanding that the upper deck where the yeast is discharged is open to the atmosphere?

Not really, there’s a tall layer of active yeast totally saturated with vigorously evolving CO2. When fermenting wort gets recirculated periodically even more CO2 gets knocked out of solution. Any O2 molecules entering the yeast head are unlikely to reach the yeast hole then the fermenting wort.

 

[eshea3]

Not really, there’s a tall layer of active yeast totally saturated with vigorously evolving CO2. When fermenting wort gets recirculated periodically even more CO2 gets knocked out of solution. Any O2 molecules entering the yeast head are unlikely to reach the yeast hole then the fermenting wort.

Wasn't addressing O2 ingress through that layer of yeast, but only that that layer of yeast is exposed to the atmosphere. Is that aspect correct?

 

[McMullan]

Wasn't addressing O2 ingress through that layer of yeast, but only that that layer of yeast is exposed to the atmosphere. Is that aspect correct?

Presumably, to the ambient air in the brewery’s fermentation room (or my fermentation chamber) to some degree, but there’s still effectively a gas barrier (blanket) being maintained by the evolving CO2 and even a ‘skin’ that forms at the interface between yeast foam and ‘air’, as well as the overflow and ‘calving’ slowly removing the top layer. So probably not that much exposure as long as fermentation is active, I’d say. Not as much as it looks in a photo without much context of what’s actually going on.

 

[eshea3]

You inspired me to do a bit of investigating. Currently one of the breweries using Yorkshire Squares is Black Sheep. Here's a link to their description of the brewing process along with an image of the work being sprayed over the top of the yeast bed. I'll leave particulars to the science guys, but if that is not sealed off from the ambient air, I'd be surprised if you're not picking up oxygen there.

https://www.blacksheepbrewery.com/our-story/our-brewing-methods/

 

[mac_1103]

an image of the work being sprayed over the top of the yeast bed. I'll leave particulars to the science guys, but if that is not sealed off from the ambient air, I'd be surprised if you're not picking up oxygen there.

That's actually yeast being sprayed onto the wort. You want to oxygenate at that step.

 

[DuncB]

Watch some videos of Harvey's beer being made, you'll see it being recirculated and sprayed through the air back onto the yeast barm.
Undoubtedly it picks up oxygen but the yeast performs better being treated this way. The beer does not manifest oxidation when served until the cask has been open to long.
But if you haven't drunk much cask ale this might not seem believable.
Lots of saisons fermented open and other Belgian beers.

 

[eshea3]

That's actually yeast being sprayed onto the wort. You want to oxygenate at that step.

According to their description that's the wort that's being sprayed over the yeast. And agree that you want to oxygenate that point so you are picking up oxygen in a Yorkshire Square

 

[Miraculix]

As long as there is strong active fermentation and lots of yeast, oxygen doesn't do damage to the beer. The yeast is so quickly absorbing it at that stage, that it doesn't have time to oxidise the beer.

Things get interesting once fermentation stops and at that point the beer is usually already packaged air tight, either with carbonation sugar or remaining gravity points to be fermented in the cask/bottle.

 

[eshea3]

Watch some videos of Harvey's beer being made, you'll see it being recirculated and sprayed through the air back onto the yeast barm.
Undoubtedly it picks up oxygen but the yeast performs better being treated this way. The beer does not manifest oxidation when served until the cask has been open to long.
But if you haven't drunk much cask ale this might not seem believable.
Lots of saisons fermented open and other Belgian beers.

So agreement then that fermentation in the Yorkshire Square results in pick up of O2. So the notion that the yeast bed completely precludes this is wrong.

 

[eshea3]

As long as there is strong active fermentation and lots of yeast, oxygen doesn't do damage to the beer. The yeast is so quickly absorbing it at that stage, that it doesn't have time to oxidise the beer.

Things get interesting once fermentation stops and at that point the beer is usually already packaged air tight, either with carbonation sugar or remaining gravity points to be fermented in the cask/bottle.

Believe that's quite similar to what I said above.

 

[McMullan]

You inspired me to do a bit of investigating. Currently one of the breweries using Yorkshire Squares is Black Sheep. Here's a link to their description of the brewing process along with an image of the work being sprayed over the top of the yeast bed. I'll leave particulars to the science guys, but if that is not sealed off from the ambient air, I'd be surprised if you're not picking up oxygen there.

https://www.blacksheepbrewery.com/our-story/our-brewing-methods/

Yes, understandably, it always seems very surprising to those who don’t appreciate how it actually works. How oxidation doesn’t occur at any noticeable level. Certainly not to any negative level. It sounds counterintuitive to the average home brewer who imagines airlocks are somehow necessary during active fermentation. I’ve tried to convince quite a few home brewers who ‘know it all’ and tell me its wrong, but ‘open’ fermentations remain surprisingly common among successful commercial breweries, including those producing some of the finest ales in England. Unlike hoppy American beers, there’s nowhere to hide flaws in the process. I’m pretty sure it would have been noted by now if the beers were flawed in any way. No shortage of literature going back to the late 19th century, if you’re interested in investigating beyond some marketing spiel.

Now, given how little O2 is considered to be sufficient to ruin a beer, it says a lot about how essentially no O2 reaches a beer in a Yorkshire square being managed properly. It mainly comes down to the skill of the brewer managing fermentation with some knowledge and good yeast management of Yorkshire yeast strains. It’s not a fermentation system I’d recommend to those who aren’t confident with brewer’s yeast, especially beasts like top-cropping Yorkshire strains.

 

[McMullan]

Watch some videos of Harvey's beer being made, you'll see it being recirculated and sprayed through the air back onto the yeast barm.
Undoubtedly it picks up oxygen but the yeast performs better being treated this way. The beer does not manifest oxidation when served until the cask has been open to long.
But if you haven't drunk much cask ale this might not seem believable.
Lots of saisons fermented open and other Belgian beers.

The fermenting wort is recirculated then sprayed through a blanket of CO2, not air (containing much O2). This is why it’s important to only recirculate (rouse) periodically during active fermentation.

 

[Miraculix]

The fermenting wort is recirculated then sprayed through a blanket of CO2, not air (containing much O2). This is why it’s important to only recirculate (rouse) periodically during active fermentation.

To be nit picky, Co2 blanket? In a wide shape like that? That is not how gasses work. There will be obviously a higher conentration of co2 closer to the brew, but there will also definitely be O2 pick up on the way from the sprinkler to the beer. But that is no problem as long as the yeast is still highly active.

 

[McMullan]

According to their description that's the wort that's being sprayed over the yeast. And agree that you want to oxygenate that point so you are picking up oxygen in a Yorkshire Square

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.

 

[Miraculix]

I like your dog.

 

[mac_1103]

Just because I don't want to try to manage an open fermentation in my own basement doesn't mean that I have any doubt that open fermentation works.

 

[mac_1103]

Oh, and my dog knows more about brewing than your dog.

 

[McMullan]

There will be obviously a higher conentration of co2 closer to the brew

Correct. And the same is true all the way to the top of the yeast trough. So unless your static textbook gas equations can break the laws of physics and the same space can be occupied by saturated CO2 continuously evolving (and rising with an updraft from all the energy being released) and air from above, I think the level of O2 in the trough is going to be so low and inconsequential for the process, it's not even of any academic interest.

 

[eshea3]

To be nit picky, Co2 blanket? In a wide shape like that? That is not how gasses work. There will be obviously a higher conentration of co2 closer to the brew, but there will also definitely be O2 pick up on the way from the sprinkler to the beer. But that is no problem as long as the yeast is still highly active.

Precisely. It's not that there's no O2 pickup, it's that the yeast and the other processes are adapted to that O2 pickup and it doesn't spoil the beer.

 

[eshea3]

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.

View attachment 841783

 

[eshea3]

Correct. And the same is true all the way to the top of the yeast trough. So unless your static textbook gas equations can break the laws of physics and the same space can be occupied by saturated CO2 continuously evolving (and rising with an updraft from all the energy being released) and air from above, I think the level of O2 in the trough is going to be so low and inconsequential for the process, it's not even of any academic interest.

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.

 

[McMullan]

Precisely. It's not that there's no O2 pickup, it's that the yeast and the other processes are adapted to that O2 pickup and it doesn't spoil the beer.

So on a number of occasions I haven't been home to seal the FV at the end of fermentation. The tall active yeast head dropped and flocculated on the bottom of the yeast trough exposing the 2" TC ferrule (yeast hole about 51mm diameter) for a day or two. A genuinely open FV. Still no signs of oxidation. So not simply the active cells in the yeast head scrubbing any O2 that might make it through. Probably because of residual CO2 still evolving, but, obviously, at a much lower rate, and the fact the trough space saturated with CO2 isn't going just disappear all of a sudden. A bit like how some harmful gases hang around causing air pollution problems. If only everything obeyed textbook equations, aye? I'd have oxidised beers too.

 

[eshea3]

So on a number of occasions I haven't been home to seal the FV at the end of fermentation. The tall active yeast head dropped and flocculated on the bottom of the yeast trough exposing the 2" TC ferrule (yeast hole about 51mm diameter) for a day or two. A genuinely open FV. Still no signs of oxidation. So not simply the active cells in the yeast head scrubbing any O2 that might make it through. Probably because of residual CO2 still evolving, but, obviously, at a much lower rate, and the fact the trough space saturated with CO2 isn't going just disappear all of a sudden. A bit like how some harmful gases hang around causing air pollution problems. If only everything obeyed textbook equations, aye? I'd have oxidised beers too.

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.

 

[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.