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General Category => Yeast and Fermentation => Topic started by: Village Taphouse on July 29, 2020, 06:57:20 PM

Title: A question on the "shaken-not-stirred" starter...
Post by: Village Taphouse on July 29, 2020, 06:57:20 PM
I know there is another thread here on this but I didn't want to hijack.  I have a stirplate and have been making starters this way for awhile with what I would call "excellent" results.  Denny had mentioned the SNS method on another board I'm on and I remember people saying that it worked well.  My question:  Is SNS better than a stirred starter or "just as good"?  Not only do I use the stirplate but I also send a bit of pure O2 into the starter as well and my starters always seem to take off and get active quickly even with older packages of yeast.  Many have said that O2 is not necessary (as well as saying stirring is not necessary) so some of this falls into the "old habits die hard" category.  On one hand, I would go with "if it ain't broken" but just curious if SNS and less O2 is actually better.  Cheers.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: BrewBama on July 29, 2020, 07:40:23 PM
With a SnS starter you actually shake the begeezies out of it until it’s foamy so you are supplying O2.


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Title: Re: A question on the "shaken-not-stirred" starter...
Post by: denny on July 29, 2020, 07:52:28 PM
Ken, my assessment is that it's at least as good as the stir plate method.  I think the yeast is healthier because it doesnt spend days on a striplate and being crashed so you can decant.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: TeeDubb on July 29, 2020, 08:21:09 PM
I switched to this method 2 years ago and never looked back. Less equipment involved, yeast seems healthier by virtue of observing a somewhat shorter lag time after being pitched. I don't use any O2 besides what the intense shaking imparts.   Stir plate is collecting dust in my closet :)
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: denny on July 29, 2020, 08:41:00 PM
I switched to this method 2 years ago and never looked back. Less equipment involved, yeast seems healthier by virtue of observing a somewhat shorter lag time after being pitched. I don't use any O2 besides what the intense shaking imparts.   Stir plate is collecting dust in my closet :)

I can't even find mine any more!I
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: ynotbrusum on July 29, 2020, 08:49:37 PM
I retired my stir plate the day I tried SNS; not sure if it is necessarily "better" from a vitality perspective (but I think it is).  It certainly seems easier to me, but if you are using a heavy jug, I suppose it might be more tiring.  I just use an apple cider jug - 1 gallon with screw cap; after shaking replace the screw cap with foil and watch for the magic.  I will usually pitch into the wort anywhere from 6-12 hours in on the starter, so there is a little advanced timing involved.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: joe_meadmaker on July 30, 2020, 03:21:52 AM
I use a stir plate, but I don't let it go for days or decant it.  I usually make my starters the night before.  Just drop it on the plate and let it go.  I usually have the starter on the stir plate for 15-18 hours by the time brewing is done and just pitch the whole thing.

I've used SNS and also think that method works perfectly well.  But for me, sanitizing a little stir bar and pressing a button is easier than shaking a starter for a period of time.  Although there is the cost of the stir plate.  I think you're good either way, they both work well.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: goose on July 30, 2020, 01:45:53 PM
I use a stir plate, but I don't let it go for days or decant it.  I usually make my starters the night before.  Just drop it on the plate and let it go.  I usually have the starter on the stir plate for 15-18 hours by the time brewing is done and just pitch the whole thing.



I do the same thing.  The nice part is I can boil my starter wort in my erlenmeyer flask (with the stir bar in the flask to sterilize it), cool the flask and the wort in an ice bath (can't do that with a glass jug since the glass will not withstand the shock of rapid cooling from boiling temperatures), pitch the yeast, and put it on the stir plate.  That way I don't have to pour off the wort into a glass jug for the SNS method.  One thing to remember especially if you are using an open flame to boil the wort in the flask, buy a wire gauze square (yuou can get them from any scientific equipment supply house to prevent hot spots on the bottom of the flask from the open flame.  Hot spots weaken the borosilicate glass and could cause it to break.  I even use it on an electric range that has a coildd burner.

That said, either way will work well.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: MNWayne on July 30, 2020, 03:12:38 PM
I'm with Joe and Goose.  I spin my flask (starting the day before brewing) in a 50 degree fridge, so when my wort has cooled to ferment temp (50F), I pour off a pint for the next batch and pitch 4 liters.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: Saccharomyces on July 30, 2020, 10:51:19 PM
I'm with Joe and Goose.  I spin my flask (starting the day before brewing) in a 50 degree fridge, so when my wort has cooled to ferment temp (50F), I pour off a pint for the next batch and pitch 4 liters.

You do know that a stir plate does nothing to improve the quality of a yeast culture?  Have you ever seen what they use to start new cultures at White Labs?  I will give you a hint.  It is not a stir plate.  Stir plates were designed for stirring solutions, not culturing microorganisms. The proper device for culturing yeast is an orbital shaker. Whoever propagated the myth that stir plates are used for yeast culturing needs to atone for his/her sins.  You should try my method of making starters (a.k.a. Shaken, not Stirred). I guarantee that it will change your outlook with respect using a stir plate, a device which is one step above worthless when culturing yeast.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: joe_meadmaker on July 31, 2020, 12:58:59 AM
The proper device for culturing yeast is an orbital shaker. Whoever propagated the myth that stir plates are used for yeast culturing needs to atone for his/her sins.  You should try my method of making starters (a.k.a. Shaken, not Stirred). I guarantee that it will change your outlook with respect using a stir plate, a device which is one step above worthless when culturing yeast.

Why is there such a big difference between the two?  I'm familiar with what an orbital shaker is.  But I'd never imagine that the effect on a yeast starter would have the orbital shaker in the 'proper device' category, but the stir plate as 'one step above worthless'.  What's happening inside the vessel just doesn't seem to be that much different.

I'm genuinely curious.  If you have any information or links to the different effects of an orbital shaker vs. a stir plate on the liquid inside the vessel, I'd love to learn more.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: MNWayne on July 31, 2020, 02:09:46 AM
Doesn't the SNS method involve a few shakings?  I set up my plate and don't touch it until the next day when it's time to pitch. So for me it's a matter of simplicity.  Orbital shaker???  Nah, the stir plate works just fine.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: TeeDubb on July 31, 2020, 03:17:45 AM
I happened to save this post from another forum by YeastWhisperer / S. cerevisiae, the person that, I believe, takes the credit for the SNS terminology and introducing it to the homebrewing community.  I think it helps explain the main benefits of stirred vs. "shaken once until very foamy" starter approach.

https://www.jimsbeerkit.co.uk/forum/viewtopic.php?f=12&t=70926&start=30 (https://www.jimsbeerkit.co.uk/forum/viewtopic.php?f=12&t=70926&start=30)

"Gas is absorbed at the interface between a gas and a liquid; therefore, gas permeability is bounded by specific surface area. One liter of medium that is shaken until it is almost foam has a huge amount of amount specific surface compared an equal amount of medium in pure liquid form. A non-direct O2-infused, stirred 1L starter does not begin to approach providing the same level of dissolved O2 to a culture at the beginning of incubation as does a well-shaken starter. In fact, a non-direct O2-infused stirred starter does not come close to providing the same amount of dissolved O2 over the entire period that a culture is stirred because most stirred starters are made in conical flasks. The surface area of the gas-liquid interface is reduced as the volume of liquid is increased in a conical shaped vessel. Almost no O2 exchange occurs after the culture starts to outgas due to the fact that the culture is under positive pressure and that CO2 is heavier than air. The cells in a stirred culture also have to deal with continuous shear stress. I am not pulling the shear stress problem out of thin air. It is a well documented and researched problem that plagues designers of bioreactors, and bioreactors stir at very slow rates while injecting O2 (perform a Google search on the terms "bioreactors" and "shear stress"). New patents are applied for in this area on a regular basis.

I can go grow a pitchable culture from a 4mm loop of yeast cells in as little as 2 days using my method. Most home brewers are pitching a culture that contained 100 billion cells at the time of packing. A four month old culture that has not been abused contains approximately 1/4th of the number of viable cells that it contained when packaged; therefore, a four-month-old White Labs vial contains approximately 25 billion viable cells, which means that we are looking at log(200 / 25 ) / log(2) = 3 replication periods to reach maximum cell density if pitched into one liter of medium or 4 replication periods if pitched into two liters of medium. If the culture is held at at least 21C, a replication period should be approximately 90 minutes; hence, we are looking at a worse case scenario of 6 hours beyond the amount of time that it takes the cells to exit the lag phase.

Anyone who is making a one or two liter starter from a commercial yeast culture several days in an advance is pitching quiescent yeast cells. Quiescent yeast cells take longer to exit the lag phase because they have to reverse the morphological changes that they underwent in preparation for quiescence. Quiescent cells also place a higher O2 load on the batch of wort into which they are pitched because they have low ergosterol and unsaturated fatty acid reserves."
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: Village Taphouse on July 31, 2020, 03:30:21 AM
I am not a scientist so I cannot claim any deep understanding of this subject.  I use a stirplate because many other homebrewers used them and suggested them.  I can take a Wyeast or White Labs pack and add it to the oxygenated starter wort that I made and the yeast will be active and ready to go exactly as joe_meadmaker described above.  If the SNS method is better somehow then I will gladly accept it but what happens when starter wort + oxygenation + liquid yeast + stirplate all get together is a beautiful thing and works exactly how I would want it.  Before the stirplate I suppose I used a variation of the SNS method and it worked... but the stirplate seemed to work better. 
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: TeeDubb on July 31, 2020, 03:53:39 AM
By virtue of people having success with both, they both work. So, to each his own. Many variables are involved and we would have to go after a careful scientific comparison to declare a winner or at least understand the trade-offs. This hobby is great at challenging us to find a balance between obsessing about details and choosing not to :)
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: MattyAHA on July 31, 2020, 12:55:51 PM
I know there is another thread here on this but I didn't want to hijack.  I have a stirplate and have been making starters this way for awhile with what I would call "excellent" results.  Denny had mentioned the SNS method on another board I'm on and I remember people saying that it worked well.  My question:  Is SNS better than a stirred starter or "just as good"?  Not only do I use the stirplate but I also send a bit of pure O2 into the starter as well and my starters always seem to take off and get active quickly even with older packages of yeast.  Many have said that O2 is not necessary (as well as saying stirring is not necessary) so some of this falls into the "old habits die hard" category.  On one hand, I would go with "if it ain't broken" but just curious if SNS and less O2 is actually better.  Cheers.

i switched to SNS exclusively for both ales and lagers and imo its equal in terms of yeast performance but SNS is a lot easier and less hassle so i say put your sir plate in the attic and forget it exists or sell it
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: denny on July 31, 2020, 01:51:02 PM
I am not a scientist so I cannot claim any deep understanding of this subject.  I use a stirplate because many other homebrewers used them and suggested them.  I can take a Wyeast or White Labs pack and add it to the oxygenated starter wort that I made and the yeast will be active and ready to go exactly as joe_meadmaker described above.  If the SNS method is better somehow then I will gladly accept it but what happens when starter wort + oxygenation + liquid yeast + stirplate all get together is a beautiful thing and works exactly how I would want it.  Before the stirplate I suppose I used a variation of the SNS method and it worked... but the stirplate seemed to work better.

Ken, I see 2 things in your post that give me a bit of pause....you use a stir plate because other homebrewers do, and you don't know that it works better.  I encourage you to do some trials to find out the truth.  And by "truth" I means what works best for you.  Don't blindly accept something without comparing it to the alternative.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: Village Taphouse on July 31, 2020, 02:55:40 PM
I am not a scientist so I cannot claim any deep understanding of this subject.  I use a stirplate because many other homebrewers used them and suggested them.  I can take a Wyeast or White Labs pack and add it to the oxygenated starter wort that I made and the yeast will be active and ready to go exactly as joe_meadmaker described above.  If the SNS method is better somehow then I will gladly accept it but what happens when starter wort + oxygenation + liquid yeast + stirplate all get together is a beautiful thing and works exactly how I would want it.  Before the stirplate I suppose I used a variation of the SNS method and it worked... but the stirplate seemed to work better.

Ken, I see 2 things in your post that give me a bit of pause....you use a stir plate because other homebrewers do, and you don't know that it works better.  I encourage you to do some trials to find out the truth.  And by "truth" I means what works best for you.  Don't blindly accept something without comparing it to the alternative.
Is there a thread here with the specific SNS steps?  I will be making a starter with 838 here within the next month or so and I will be happy to try it.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: MattyAHA on July 31, 2020, 03:06:52 PM
boil up a quart of 1.035-40 wort, chill it, put in a gallon vessel and shake it like a mad man until its foam, add yeast and pitch at high krausen, bada bing bada boom
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: Village Taphouse on July 31, 2020, 03:09:59 PM
boil up a quart of 1.035-40 wort, chill it, put in a gallon vessel and shake it like a mad until its foam, pitch yeast and pitch at high krausen, bada bing bada boom
Thanks for that.  Can do.

Btw... I was not saying "stirplates were the way to go" just because other brewers mentioned them.  That's just how I happened to be the owner of one and I have been very happy with how my starters have gone and how the resulting beers have been when that starter was used.  Before the stirplate I would simply make the starter wort, oxygenate it and place the starter flask in the basement and swirl it every time I walked past it.  That's not SNS but the stirplate was better than my no-stirplate attempts. 
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: denny on July 31, 2020, 03:27:57 PM
I am not a scientist so I cannot claim any deep understanding of this subject.  I use a stirplate because many other homebrewers used them and suggested them.  I can take a Wyeast or White Labs pack and add it to the oxygenated starter wort that I made and the yeast will be active and ready to go exactly as joe_meadmaker described above.  If the SNS method is better somehow then I will gladly accept it but what happens when starter wort + oxygenation + liquid yeast + stirplate all get together is a beautiful thing and works exactly how I would want it.  Before the stirplate I suppose I used a variation of the SNS method and it worked... but the stirplate seemed to work better.

Ken, I see 2 things in your post that give me a bit of pause....you use a stir plate because other homebrewers do, and you don't know that it works better.  I encourage you to do some trials to find out the truth.  And by "truth" I means what works best for you.  Don't blindly accept something without comparing it to the alternative.
Is there a thread here with the specific SNS steps?  I will be making a starter with 838 here within the next month or so and I will be happy to try it.

I'm sure it's here somewhere, but here are my instructions, which are the same...https://www.experimentalbrew.com/blogs/denny/old-dognew-tricks
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: denny on July 31, 2020, 03:29:15 PM
boil up a quart of 1.035-40 wort, chill it, put in a gallon vessel and shake it like a mad until its foam, pitch yeast and pitch at high krausen, bada bing bada boom
Thanks for that.  Can do.

Btw... I was not saying "stirplates were the way to go" just because other brewers mentioned them.  That's just how I happened to be the owner of one and I have been very happy with how my starters have gone and how the resulting beers have been when that starter was used.  Before the stirplate I would simply make the starter wort, oxygenate it and place the starter flask in the basement and swirl it every time I walked past it.  That's not SNS but the stirplate was better than my no-stirplate attempts.

And you may find you still prefer the stir plate in terms of performance or ease of use.  But you won't know til you try SNS.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: Saccharomyces on July 31, 2020, 10:22:40 PM
I am both Yeast Whisper and S. Cerevisiae. They are my old user names on two different sites.  Denny and those who are in the know can attest to the fact that I changed my user name on this site in 2016 (I have a blog on Denny and Drew's site under which I blogged as Saccharomyces).  I did so because my ex-wife reported a neighbor to county zoning who was illegally using his residential property as a commercial high-performance automotive service shop, complete with a dynamometer that was unbelievably loud when in use.  His customers also used to burn-out in front our home when leaving his illegal shop (the road looked like a drag strip).  When he lost his battle with zoning, my neighbor decided to attempt to make our lives miserable. Not only did he damage property we owned, he cyber stalked us and attempted to ruin our reputations. He reported that I was posting to this forum on company time after he made the connection between my real name and my user name on the site.  As much as I hated it, I accepted that consequence because I was doing something wrong that needed to be corrected (which is why I no longer post during the day during the work week).  However, the straw that broke the camel’s back was when he started to cause trouble on this forum and harass AHA headquarters.  That is when I decided to close my S. cerevisiae account and create my Saccharomyces account. People I know from the site who I met at NHC have kept my real identity undisclosed because they know the back story, which is something that I appreciate. 

With that said, not wanting to pour media into a glass container is a non sequitur.  I switched to using a 5L borosilicate glass (Pyrex and Kimax are common brand names for borosilicate glass) media bottle years ago, so that I did not have to wait until the starter medium cooled (I believe that there are photos of my old Corning 5L media bottle on this site as well as the site on which I posted as Yeast Whisper). Large media bottles are not cheap new from a labware supply company, but they can be had new for 50% of what they cost from a labware supplier on eBay if one is patient and even less if one is willing to go second hand.  Starter media can be poured into a borosillicate glass media bottle or any other borosilicate glass labware hot, which means that all the media bottle and GL45 cap need to be is clean.  The starter medium will sanitize the media bottle and the loosely attached GL45 cap if allowed to stand for around 30 minutes before cooling because the starter medium will bring the bottle and cap up to at least the Pasteurization temperature of 145F (the time period is reduced to 15 seconds if the bottle and cap reach 161F).  That is a heck of a lot safer than boiling in an Erlenmeyer flask, as is practiced by many homebrewers.  Due to their design, Erlenmeyer flasks are not designed to be used for boiling, which is why they tend to break when put on a heat source.  The proper piece of glass labware to use for boiling is a boiling flask, which is round to evenly disperse the stress that occurs when heated. 

An orbital shaker is a very different device than a stir plate. The flasks that are normally used on orbital shakers may resemble an Erlenmeyer flask, but there are significant differences.  Shaker flasks have baffles on the bottom.  They also tend to be wider and shorter.  The wider body is to increase the surface area for oxygen diffusion. The baffles exist to increase turbulence, which causes the media to foam.  What most homebrewers do not know is that yeast cultures do not use oxygen in the average starter after the they have entered the log phase where exponential growth occurs due to the fact that the medium is above the Crabtree threshold.  The keeping the yeast in suspension using a stir bar argument also demonstrates a complete lack of understanding of how yeast cells behave.  Viable yeast cells naturally stay in suspension until they have exhausted all of the sugars that they can metabolize; therefore, there is no need to stir.   All stirring does is keep non-viable cells in suspension. Shaking the medium into foam provides significantly more dissolved O2 than a stir plate does the entire time it is spinning the bar.  The stir bar also places shear stress on the cells, which is why the starter medium from a stirred culture smells foul. Even if one allows a Shaken, not Stirred (SNS) culture to ferment out and enter quiescence, it never smells foul unless the starter has been contaminated. An SNS starter is also significantly easier to make and much cheaper if a repurposed 1-gallon apple juice jug is used (the caveat is that the temperature differential between the jug and the starter medium cannot be large).

The reason why one pitches at high krausen is because it signals the shift from exponential growth to the stationary phase. What that means to a brewer is that he/she has obtained maximum cell density without allowing the yeast cells to unnecessarily expend unsaturated fatty acids (UFAs) and ergosterol reserves, which means that less oxygen and time are necessary for the lag phase after the culture has been pitched.  The UFAs and ergosterol that the mother cells store during the lag phase are shared with all of their daugther cells. The cells that are produced after the exponential phase has completed are for replacement only; therefore, they unnecessarily deplete UFAs and ergosterol.  If one allows the cells to enter quiesence, one has to deal with cells that have undergone morphological changes in order to survive lack of carbon to metabolize for energy.  Sugars are carbohydrates.  Carbohydrates are composed of carbon bound to water (read my article entitled “Carbon Credits,” https://www.experimentalbrew.com/blogs/saccharomyces/carbon-credits).

What we need to remember is that knowledge is power and myth is just that, myth.  One can either except myth or one can seek to understand what is actually happening during cell culture.  However, to say that using a stir plate produces a better culture is just mythological nonsense.  A stir plate is better than just pitching a culture into a starter medium without any attempt to oxygenate the medium in some way, but that is a pretty low bar.  The time to add oxygen to a culturing medium is before the culture is pitched or right after it has been pitched.  If one gets that right, the rest is easy.  The specific surface area provided to a culture in an Erlenmeyer flask is not large enough to cause significant oxygen diffusion.  Sure, stirring the culture fast enough to create a vortex improves the situation by increasing the specific surface area and exposing more of the medium to the slightly larger specific surface area by turning it over, but it comes at higher sheer stress.  Here’s an experiment to try.  Make two starters and place them on stirplates for 24 hours.  The first culture is spun fast enough to create a significant vortex.  The second culture is spun very slowly.   Now, smell each culture after 24 hours have elapsed.  More often than not, the culture that was spun fast enough to create a significant vortex will smell much worse than the culture than was spun slowly.   That is the smell of shear stress. Shear stress negatively impacts the health of the yeast cells.

In then end, if one wants to use a piece of mechanical lab equipment to make starters, one should stick to using an orbital shaker and shaker flasks.  That is what White Labs uses when starting new yeast cultures from working cultures in their bank (The orbital shaker used in the propagation lab is an amazing thing to see because it is multi-level).  White Labs stores its long-term cultures in a liquid nitrogen-fueled freezer that is capable of reaching -196C.   

Here is a link from probrewer.com where the author covers propagating yeast directly from a single-cell isolation plate (each distinct round colony is the offspring of a single yeast cell):

https://discussions.probrewer.com/forum/probrewer-message-board/brewery-operations/yeast-q-a-sponsored-by-lallemand/34576-laboratory-propegation-and-brewery-propegation-of-yeast-sops   

Usually, one or more colonies are aseptically transferred to an agar slant for storage and the first-level starter is innculated from slant, not directly from a plate (however, starting from a single colony ensures that the culture grown is a single-cell pure culture).  I will often transfer more than one colony to slant or create several slants from individual colonies if I suspect that a yeast culture is multi-strain.  That is what I did when I cultured from a hydrometer sample I collected at a Ringwood brewery back in 1993.

Title: Re: A question on the "shaken-not-stirred" starter...
Post by: 4dogbrewer on August 24, 2020, 11:39:54 AM
What if you don't want all of the starter ( 5 L ) in your lager using the SNS method. Can you still crash cool and decant using the SNS method?
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: 69franx on August 24, 2020, 12:21:25 PM
You can but it defeats the purpose of SNS which is to pitch an active starter at high krausen

Sent from my SM-A515U1 using Tapatalk

Title: Re: A question on the "shaken-not-stirred" starter...
Post by: denny on August 24, 2020, 01:46:29 PM
What if you don't want all of the starter ( 5 L ) in your lager using the SNS method. Can you still crash cool and decant using the SNS method?

I used to worry about that.  Then I tried it.  I no longer worry about it.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: Saccharomyces on August 24, 2020, 08:23:39 PM
What if you don't want all of the starter ( 5 L ) in your lager using the SNS method. Can you still crash cool and decant using the SNS method?

The starter is not 5L in volume.  It is 1L of starter in a 1 gallon jug or a 5L media bottle.  The empty space is part of the equation when shaking.  Secondly, as others have mentioned, crash cooling and decanting adds no value to the process while delaying pitching time, which is critical.  It is important to pitch the culture when it hits high krausen.  That is where the biggest bang for the buck is achieved.  Also, starter media made with pale spray malt is basically neutral in flavor.  The funky smells and tastes from a stirred starter are the result of stress on the yeast cells.  That is why a stirred starter has to be crash cooled and decanted. Other than introducing an infection, allowing a starter to ferment out and enter quiescence is one of the worse things one can do to a starter.  At the end of fermentation, yeast cells undergo morphological changes where the cell wall thickens in preparation for hard times.  If one waits until a starter fements out, there morphological changes have to be undone after the culture is pitched, which extends the lag phase.  Anything that extends lag time is bad for fermentation because yeast cells are in competition with an enemy that grows by a factor of eight in the time it takes for the yeast cell count to double.

By the way, I go into lengthy details was to how yeast biomass grows in this blog entry: https://www.experimentalbrew.com/blogs/saccharomyces/yeast-cultures-are-nuclear-weapons
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: Richard on August 24, 2020, 09:11:32 PM
Not mentioned in this discussion so far is that, as I understand it, there is no need to oxygenate your wort when using a SNS starter. The SNS method provides the yeast with enough oxygen to make all the compounds they need before being added to the wort. So, in addition to not needing a stir plate you also do not need oxygen tank, regulator, wand, stone, etc.
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: denny on August 24, 2020, 09:14:21 PM
Not mentioned in this discussion so far is that, as I understand it, there is no need to oxygenate your wort when using a SNS starter. The SNS method provides the yeast with enough oxygen to make all the compounds they need before being added to the wort. So, in addition to not needing a stir plate you also do not need oxygen tank, regulator, wand, stone, etc.

I don't think it's oxygen...i think it's sterols produced from the oxygen. 
Title: Re: A question on the "shaken-not-stirred" starter...
Post by: Saccharomyces on August 24, 2020, 09:23:23 PM
That is correct. You do not need an oxygen tank.  The method relies on the high specific surface area provided by foam to maximize oxygen (O2) diffusion from the air inside of the jug or media bottle. That is why I specified at least a 4 to 1 ratio for the container size and the starter size.  After shaking, the yeast take up the dissolved O2 and use it to synthesize ergosterol and unsaturated fatty acids (UFAs).  These compounds are vital for yeast cell wall health.  The ergosterol and UFA reserves stored by the mother cells during the lag phase are shared with all of their daughter cells during the log phase (a.k.a. exponential growth phase) because no O2 is used during the exponential phase due to the medium being above the Crabtree threshold.  High krausen marks the shift from exponential growth to the stationary phase where new yeast cells are only produced to replace dead yeast cells.  So, while a stirred culture may appear to have more yeast cells, many of the yeast cells are non-viable because a culturing medium has a maximum cell density that cannot be exceeded.