[Village Taphouse]

Sounds like a pretty extreme example (removing the foam) that doesn't support a general rule, but I have to acknowledge that I haven't listened to the podcast and Dr. Bamforth has forgotten more beer knowledge than I have ever learned.

Right.  All hail the Pope of Foam. 

[Megary]

This may be a dumb question…

Is there any reason to believe that swirling or rousing the fermenter actually restarts yeast that have dropped out or have otherwise given up?  I hear this a lot, but I’ve never experienced any additional activity when I have tried it.  Time mostly, but also a bump in temperature (before it’s too late) seem to be the only arm-twisting I can use to successfully encourage the yeast along.

I don't buy it myself. If the yeast has already formed flocs and dropped out of suspension, then shaking the flocs back up isn't going to bring the yeast out of dormancy to further attenuate a wort that they already quit on.

In all likelihood this is an old brewers' tale that dates back to the days where "active fermentation" was determined by airlock activity rather than hydrometer readings. Swirling the fermenter probably knocked some CO2 out of solution and made it look like fermentation had restarted.

Imagine this:  I have S-04 running in an ale and it's on my basement floor where it's cool and after a few days fermentation stops.  Then I carry it upstairs to a warmer place and I rouse the fermenter and yes, of course I would get some bubbling because I roused the yeast and then I might allow a few hours to go by and do that again with the wort warmer and now... for another 5-6 hours I have steady blooping in my bucket of sanitizer because the yeast warmed up and knocked the gravity down a few more ticks.  Are you thinking that if I had just moved the fermenter and not roused it the yeast would warm up and do all of that final fermenting on its own?  I'm not arguing it, I'm just curious.  I hate underfermented/sweet beer.  I want a dry finish and I want my yeast to complete it's important work.  I also want to eliminate diacetyl in a yeast strain that is known for it.

My experience has been that whatever yeast settles to the bottom is no longer helpful.  If I were to swirl that up, all it would do for me is clog the spigot on the fermenter.   

[Village Taphouse]

My experience has been that whatever yeast settles to the bottom is no longer helpful.  If I were to swirl that up, all it would do for me is clog the spigot on the fermenter.   

I was under the impression that cooler temps could allow for the yeast to drop before all the work was done and warming it up could get whatever fermentation remaining to kick in and also [potentially] help drive off/reduce/take out diacetyl.  That could be complete nonsense.  The other thing is that I make A LOT of lagers which are also prone to diacetyl [the S-04 thing applies to yeast I'm using now and it also is known for diacetyl] and I will allow the lager yeast to work around 50° but once fermentation begins to slow I'll move the fermenter to a warmer spot for the rest of fermentation.  Same principle.  But if someone smarter than me says that once yeast drops out [regardless of temp] then rousing it does nothing... I am all ears. 

[MDL]

Seems to me if you pitch enough healthy yeast and  ferment at a reasonable temp you shouldn’t need to rouse most yeast. I have heard about some British strains that require much more oxygen to ferment to completion, like in open fermenters, so perhaps rousing might help in this type of fermentation. I worked with a guy who used to brew for Shipyard Brewing in Maine. He said they open ferment and actually pump the beer back into the open tank through a spray wand to rouse and aerate to get the yeast to finish fermentation. They also top crop generations of yeast for eternity.

[Megary]

My experience has been that whatever yeast settles to the bottom is no longer helpful.  If I were to swirl that up, all it would do for me is clog the spigot on the fermenter.   

I was under the impression that cooler temps could allow for the yeast to drop before all the work was done and warming it up could get whatever fermentation remaining to kick in and also [potentially] help drive off/reduce/take out diacetyl.  That could be complete nonsense.  The other thing is that I make A LOT of lagers which are also prone to diacetyl [the S-04 thing applies to yeast I'm using now and it also is known for diacetyl] and I will allow the lager yeast to work around 50° but once fermentation begins to slow I'll move the fermenter to a warmer spot for the rest of fermentation.  Same principle.  But if someone smarter than me says that once yeast drops out [regardless of temp] then rousing it does nothing... I am all ears.

You might be right, I’m certainly no expert.  And I brew 95% ales, so there’s that.
But maybe warming your fermentation is only helping the yeast still active and still in suspension??  And the swirling or rousing isn’t resurrecting any spent yeast??  This is where the science leaves my atmosphere and I have to rely on what I have observed in practice. 

[Village Taphouse]

My experience has been that whatever yeast settles to the bottom is no longer helpful.  If I were to swirl that up, all it would do for me is clog the spigot on the fermenter.   

I was under the impression that cooler temps could allow for the yeast to drop before all the work was done and warming it up could get whatever fermentation remaining to kick in and also [potentially] help drive off/reduce/take out diacetyl.  That could be complete nonsense.  The other thing is that I make A LOT of lagers which are also prone to diacetyl [the S-04 thing applies to yeast I'm using now and it also is known for diacetyl] and I will allow the lager yeast to work around 50° but once fermentation begins to slow I'll move the fermenter to a warmer spot for the rest of fermentation.  Same principle.  But if someone smarter than me says that once yeast drops out [regardless of temp] then rousing it does nothing... I am all ears.

You might be right, I’m certainly no expert.  And I brew 95% ales, so there’s that.
But maybe warming your fermentation is only helping the yeast still active and still in suspension??  And the swirling or rousing isn’t resurrecting any spent yeast??  This is where the science leaves my atmosphere and I have to rely on what I have observed in practice.

I hear you.  Same with me.  I'm experience-driven, not science-driven.  Someone will be along any minute to set us straight and that's why we hang out here... so people who know their stuff can feed us their knowledge and personal experiences.   

[Megary]

My experience has been that whatever yeast settles to the bottom is no longer helpful.  If I were to swirl that up, all it would do for me is clog the spigot on the fermenter.   

I was under the impression that cooler temps could allow for the yeast to drop before all the work was done and warming it up could get whatever fermentation remaining to kick in and also [potentially] help drive off/reduce/take out diacetyl.  That could be complete nonsense.  The other thing is that I make A LOT of lagers which are also prone to diacetyl [the S-04 thing applies to yeast I'm using now and it also is known for diacetyl] and I will allow the lager yeast to work around 50° but once fermentation begins to slow I'll move the fermenter to a warmer spot for the rest of fermentation.  Same principle.  But if someone smarter than me says that once yeast drops out [regardless of temp] then rousing it does nothing... I am all ears.

You might be right, I’m certainly no expert.  And I brew 95% ales, so there’s that.
But maybe warming your fermentation is only helping the yeast still active and still in suspension??  And the swirling or rousing isn’t resurrecting any spent yeast??  This is where the science leaves my atmosphere and I have to rely on what I have observed in practice.

I hear you.  Same with me.  I'm experience-driven, not science-driven.  Someone will be along any minute to set us straight and that's why we hang out here... so people who know their stuff can feed us their knowledge and personal experiences.   

 

[BrewBama]

... I have heard about some British strains that require much more oxygen to ferment to completion, like in open fermenters, so perhaps rousing might help in this type of fermentation. … they open ferment and actually pump the beer back into the open tank through a spray wand to rouse and aerate to get the yeast to finish fermentation. They also top crop generations of yeast for eternity.

Sounds like a pretty good description of Yorkshire Squares:

[MDL]

... I have heard about some British strains that require much more oxygen to ferment to completion, like in open fermenters, so perhaps rousing might help in this type of fermentation. … they open ferment and actually pump the beer back into the open tank through a spray wand to rouse and aerate to get the yeast to finish fermentation. They also top crop generations of yeast for eternity.

Sounds like a pretty good description of Yorkshire Squares:



Cool pic. That would make sense as the story is that Shipyard uses some old Ringwood yeast strain.

[fredthecat]

Sounds like a pretty good description of Yorkshire Squares:

i want to set up an open fermentation system for when/if i ever get a hold of WLP037 or W1469 or certain other british strains. i guess just a brew bucket with a paintstrainer over top

[denny]

Sounds like a pretty good description of Yorkshire Squares:

i want to set up an open fermentation system for when/if i ever get a hold of WLP037 or W1469 or certain other british strains. i guess just a brew bucket with a paintstrainer over top

Sierra Nevada open ferments their hefeweizen

[fredthecat]

Sierra Nevada open ferments their hefeweizen

never had SN hefeweizen before, but yes could also definitely use it for weisse beers and belgians and perhaps more.

[hopfenundmalz]

Sounds like a pretty good description of Yorkshire Squares:

i want to set up an open fermentation system for when/if i ever get a hold of WLP037 or W1469 or certain other british strains. i guess just a brew bucket with a paintstrainer over top

Sierra Nevada open ferments their hefeweizen

And Bigfoot.

[denny]

Sounds like a pretty good description of Yorkshire Squares:

i want to set up an open fermentation system for when/if i ever get a hold of WLP037 or W1469 or certain other british strains. i guess just a brew bucket with a paintstrainer over top

Sierra Nevada open ferments their hefeweizen

And Bigfoot.

Ah, yes, forgot that one.  I have pics of the hefe fermenters.

[Cliffs]

Sounds like a pretty good description of Yorkshire Squares:

i want to set up an open fermentation system for when/if i ever get a hold of WLP037 or W1469 or certain other british strains. i guess just a brew bucket with a paintstrainer over top

Sierra Nevada open ferments their hefeweizen

And Bigfoot.

Bigfoot is the best barleywine in the world and I'm willing to die on this hill