[KellerBrauer]

This has been a very interesting subject indeed.  However, my opinion is that way too much emphasis has been placed on it.  Unless one is brewing in a vacuum (literally) the inclusion of oxygen into the process is inevitable.  I further believe it’s most important to minimize the inclusion of oxygen post fermentation than it is pre fermentation.  I think, after reading all the expert opinions in this thread, that oxygen inclusion, preboil, seems to be a major effort in futility.

[Big Monk]

This has been a very interesting subject indeed.  However, my opinion is that way too much emphasis has been placed on it.  Unless one is brewing in a vacuum (literally) the inclusion of oxygen into the process is inevitable.  I further believe it’s most important to minimize the inclusion of oxygen post fermentation than it is pre fermentation.  I think, after reading all the expert opinions in this thread, that oxygen inclusion, preboil, seems to be a major effort in futility.

It’s actually extremely easy to exclude oxygen throughout the process but the discussion of how and why is outside the bounds of this thread.

I think everyone can agree, as always, on the importance of cold side oxygen exclusion.

[wobdee]

It seems there is a great deal of discussion pertaining to Hot Side vs. Cold Side of the brewing process.  Instead, shouldn’t the discussion be Pre-Aeration and Post-Fermentation?  Perhaps I simply don’t understand the conversation.  But we want oxygen in the wort when we pitch.  Then, we work to avoid inclusion of oxygen after fermentation.

I want as much splashing as possible when I pump my wort from the BC through my plate cooler and into the fermenter; this can only help fermentation.

So why would oxygen on the hot side be of any concern?  Am I missing something?

You want a controlled addition of oxygen at the right time, i.e. in cooled, pre-fermentation wort. Oxygen is orders of magnitude less reactive with the wort  at pitching temperatures than at mash temps. The rates at which oxygen will affect a chilled wort are such that an active pitch of yeast will chew through it before it could ever cause any damage.

To be safe ive gone to a vitality starter rather than relying on oxygenating the wort. Im not so sure that the yeast will take care of the O2 in the wort prior to it doing some damage. Ive read that it takes yeast 30 minutes or more to use up the O2 in wort. This seems like a long time to me where there may be some damage happening?

[ynotbrusum]

Here you go :

https://www.morebeer.com/articles/how_yeast_use_oxygen

Pretty much answers the question.

[Robert]

Here you go :

https://www.morebeer.com/articles/how_yeast_use_oxygen

Pretty much answers the question.

Thanks for pointing out this excellent summary.   It is important to separate the two very distinct functions oxygen performs in yeast metabolism.   If one could get past all the recent screaming of "Crabtree! Crabtree!  Yeast doesn't respire!" it would become quite clear why actual, practical experience demonstrates that a starter on a stir plate, exchanging CO₂ for O₂,  produces a far greater mass of far healthier yeast, leading to better ordered fermentations, better beer,  and yeast better prepared for repitching, and why it is important to decant the liquid containing undesirable products no matter how you grow your starter.  Common sense may come round yet again.  (Standard disclaimer, YMMV, it's all a crapshoot with homebrew.)

[mabrungard]

It’s actually extremely easy to exclude oxygen throughout the process but the discussion of how and why is outside the bounds of this thread.

I think everyone can agree, as always, on the importance of cold side oxygen exclusion.

I've incorporated many refinements to my methods and equipment to reduce oxygen uptake on both the hot and cold sides. For some styles (light malty), I find that it definitely makes a difference. But not so much for others.

The ease with which I incorporated those measures was probably increased since I already ran a RIMS. For brewers employing more mash mixing, it may not be nearly as easy and they are less likely to note a difference even in those beer styles that benefit.

At a minimum, I strongly encourage brewers to focus on eliminating post-fermentation oxygen contact during transfer and packaging. That definitely improves the longevity of your beers.

[Big Monk]

I've incorporated many refinements to my methods and equipment to reduce oxygen uptake on both the hot and cold sides. For some styles (light malty), I find that it definitely makes a difference. But not so much for others.

I will say that I have a very limited scope of beers brewed. I do Trappist “style” ales, Pale Ale, 9% Imperial Stout and Brown Ale. I’ve noticed the difference in all of them, especially my Trappist beers. Overall I agree with you though. For many this may be another tool in the toolbox to nail paler beers.

The ease with which I incorporated those measures was probably increased since I already ran a RIMS. For brewers employing more mash mixing, it may not be nearly as easy and they are less likely to note a difference even in those beer styles that benefit.

I disagree here. For single infusion without recirc, gentle stirring and Metabisulfite are your friend. We have a number of very successful single infusion brewers with very simple cooler rigs and a spoon for stirring.

At a minimum, I strongly encourage brewers to focus on eliminating post-fermentation oxygen contact during transfer and packaging. That definitely improves the longevity of your beers.

Absolutely no one in this day and age should disagree with you here.

[denny]

Here you go :

https://www.morebeer.com/articles/how_yeast_use_oxygen

Pretty much answers the question.

Thanks for pointing out this excellent summary.   It is important to separate the two very distinct functions oxygen performs in yeast metabolism.   If one could get past all the recent screaming of "Crabtree! Crabtree!  Yeast doesn't respire!" it would become quite clear why actual, practical experience demonstrates that a starter on a stir plate, exchanging CO₂ for O₂,  produces a far greater mass of far healthier yeast, leading to better ordered fermentations, better beer,  and yeast better prepared for repitching, and why it is important to decant the liquid containing undesirable products no matter how you grow your starter.  Common sense may come round yet again.  (Standard disclaimer, YMMV, it's all a crapshoot with homebrew.)

I just haven't found your concerns to be anything other than theoretical.  I have found non stir plate starters, pitched with the starter wort to make beer that is at least equivalent to what I was doing before.  There's common sense, and there's practical experience.  YMMV, but again I think you're painting with too broad a brush. 

[klickitat jim]

Here you go :

https://www.morebeer.com/articles/how_yeast_use_oxygen

Pretty much answers the question.

Thanks for pointing out this excellent summary.   It is important to separate the two very distinct functions oxygen performs in yeast metabolism.   If one could get past all the recent screaming of "Crabtree! Crabtree!  Yeast doesn't respire!" it would become quite clear why actual, practical experience demonstrates that a starter on a stir plate, exchanging CO₂ for O₂,  produces a far greater mass of far healthier yeast, leading to better ordered fermentations, better beer,  and yeast better prepared for repitching, and why it is important to decant the liquid containing undesirable products no matter how you grow your starter.  Common sense may come round yet again.  (Standard disclaimer, YMMV, it's all a crapshoot with homebrew.)

I just haven't found your concerns to be anything other than theoretical.  I have found non stir plate starters, pitched with the starter wort to make beer that is at least equivalent to what I was doing before.  There's common sense, and there's practical experience.  YMMV, but again I think you're painting with too broad a brush.

I wish we could use two different terms for what everyone calls "starters". To me a "starter" simply starts the yeast, gets it out of dormancy, begins its phases of activity. What many people call a "starter" is probably a propagator...  if the "starter" completes or nearly completes the yeast life cycle, in my book it's propagation not a starter, and unless it's a properly handled drinkable beer, it ought to be decanted and discarded.

[Robert]

Here you go :

https://www.morebeer.com/articles/how_yeast_use_oxygen

Pretty much answers the question.

Thanks for pointing out this excellent summary.   It is important to separate the two very distinct functions oxygen performs in yeast metabolism.   If one could get past all the recent screaming of "Crabtree! Crabtree!  Yeast doesn't respire!" it would become quite clear why actual, practical experience demonstrates that a starter on a stir plate, exchanging CO₂ for O₂,  produces a far greater mass of far healthier yeast, leading to better ordered fermentations, better beer,  and yeast better prepared for repitching, and why it is important to decant the liquid containing undesirable products no matter how you grow your starter.  Common sense may come round yet again.  (Standard disclaimer, YMMV, it's all a crapshoot with homebrew.)

I just haven't found your concerns to be anything other than theoretical.  I have found non stir plate starters, pitched with the starter wort to make beer that is at least equivalent to what I was doing before.  There's common sense, and there's practical experience.  YMMV, but again I think you're painting with too broad a brush.

I was referring to the line of arguement I've encountered that "since yeast don't respire, a stir plate couldn't possibly help, so you shouldn't ever use it" while there's plenty of published and practical evidence to the contrary.  This explains why. Continuous gas exchange can improve growth and health, and it has nothing to do with respiration.   So it can be useful, but that depends on lots of other aspects of your process.  I personally rarely use a stir plate, my starters are usually too big, so just O2 at the start.  But I'm still in the camp going for maximum cell count and long term health, because I'm not pitching at high kräusen, just doesn't fit my brew schedule.  If you are, then you can't decant, so you want to avoid excessive aeration of the starter to avoid pitching off flavors with your yeast. If you plan to repitch, other  concerns are involved.  There's no single optimal method, but no wrong one either. The article provides insight into some subtleties than can help you decide on what aeration practices best suit your own yeast handling and fermentation procedures.  I think it's a good resource.   I'll have to reread it at an earlier hour of the day, saw that post on my way to bed.

I like Jim's point a lot.  There are two models here, as there are two stages of yeast growth in breweries:  lab propagation, stepping up at high kräusen,  and brewery propagation, successive completed and decanted batches.  The "vitality starter"  follows the lab model, the decanted "starter" the brewery model.  Distinguishing between the two, with their different goals, would eliminate confusion about the "right" way to conduct them.  FWIW I have always personally referred to my procedure as "propagation," not a "starter."  But in general conversation that subtlety gets lost.

[denny]

Here you go :

https://www.morebeer.com/articles/how_yeast_use_oxygen

Pretty much answers the question.

Thanks for pointing out this excellent summary.   It is important to separate the two very distinct functions oxygen performs in yeast metabolism.   If one could get past all the recent screaming of "Crabtree! Crabtree!  Yeast doesn't respire!" it would become quite clear why actual, practical experience demonstrates that a starter on a stir plate, exchanging CO₂ for O₂,  produces a far greater mass of far healthier yeast, leading to better ordered fermentations, better beer,  and yeast better prepared for repitching, and why it is important to decant the liquid containing undesirable products no matter how you grow your starter.  Common sense may come round yet again.  (Standard disclaimer, YMMV, it's all a crapshoot with homebrew.)

I just haven't found your concerns to be anything other than theoretical.  I have found non stir plate starters, pitched with the starter wort to make beer that is at least equivalent to what I was doing before.  There's common sense, and there's practical experience.  YMMV, but again I think you're painting with too broad a brush.

I wish we could use two different terms for what everyone calls "starters". To me a "starter" simply starts the yeast, gets it out of dormancy, begins its phases of activity. What many people call a "starter" is probably a propagator...  if the "starter" completes or nearly completes the yeast life cycle, in my book it's propagation not a starter, and unless it's a properly handled drinkable beer, it ought to be decanted and discarded.

But isn't the same thing true of the wort no matter what you call it?  Maybe I'm misunderstanding you, but are you saying it's OK to pitch wort from a starter, but not a propagator?

[Robert]

^^^^
If it tastes ok, sure, pitch it.  But (this is referenced in the article in question) if you continuously aerate the propagation,  which may be advisable,  it's not going to taste good.  So decant.  Case by case.

[denny]

^^^^
If it tastes ok, sure, pitch it.  But (this is referenced in the article in question) if you continuously aerate the propagation,  which may be advisable,  it's not going to taste good.  So decant.  Case by case.

I agree that if you continuously aerate it won't taste good and you shouldn't pitch it.  But I don't believe you were that specific in your previous statement.  Sounds like we're in agreement.

[narcout]

I was referring to the line of arguement I've encountered that "since yeast don't respire, a stir plate couldn't possibly help, so you shouldn't ever use it" while there's plenty of published and practical evidence to the contrary.

Maybe I've missed it, but I don't think I've heard anyone say that.

The Crabtree Effect doesn't mean yeast don't utilize oxygen to synthesize sterols, etc. or that oxygen isn't beneficial.

[hmbrewing]

I'm just not at that part of my "brewing career" that I want to worry about HSA. I'm not saying I splash the hell out of my wort. I take measures to ensure my recirc tube is below the mash level and small stuff like that. But, beyond that - I just can't see complicating my brew day. The beer that I brew, keg, and enjoy is just too delicious to justify complicating it at this time. Could it be better if I watch my HSA? I don't know, maybe. But I've spent time on changes like building water from distilled and controlling fermentation temperatures to within 1 degree. These 2 changes alone have greatly improved the quality of my beer but I also recognized that I needed to make those changes due to inconsistency from batch to batch. As of right now I'm not picking up on anything that makes me want to start worrying about HSA.

I also only brew 2.5g batches. It's possible this whole HSA thing is more concerning at larger scales. I don't know. Not an expert on this.