Author Topic: New starter procedure trial  (Read 33613 times)

Offline narvin

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Re: New starter procedure trial
« Reply #225 on: October 08, 2015, 03:40:24 AM »
Cheap and easy is great, but even Denny has a stir plate.  Many of us are looking for the best method that's practical.  Modern homebrewers wouldn't think twice about getting a disposable O2 tank and cheap "regulator" (the valve that williams sells that doesn't include an actual regulator) if it were significantly better or easier.  You don't need an oxygen tank and welding regulator, but it saves money and makes things repeatable.  However, for a starter it sounds like that doesn't matter.  Saturate it and let 'er rip!

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Re: New starter procedure trial
« Reply #226 on: October 08, 2015, 03:45:26 AM »
There is a difference between ergosterol and UFA levels between high krausen and quiescent cells.

Yes, but by how much? Is this measurable? After two days on a stir plate, will my yeast have 98% as much nutrients in reserve as they did at high krausen? 75%? 50%? How big of a difference is significant for fermentation performance, given the fact that these same nutrients are going to be available in 20x more quantity in the wort the yeast will be pitched into?

Kai Troester also did some experiments where he showed that high stir plate speed significantly increased the number of cells grown in the same starter culture when compared to a low speed with no vortex (http://braukaiser.com/blog/blog/2013/03/25/stir-speed-and-yeast-growth/). Presumably, a non-stirred starter would grow the same number or fewer cells than the low speed starter. If I grew X number of cells using a James Bond starter, and 2*X cells using a stir plate starter, but the stir plate starter cells had 50% as many nutrients in reserve as the James Bond cells, what difference in fermentation performance can I expect, given that after a single replication period, the James Bond cells would be at 50% reserves and number at 2*X?

I'm also wondering whether shear stress can cause permanent damage to a culture. Let's say I grew a culture on a stir plate, cold crashed it, then decanted the spent wort. Then I added fresh wort, removed the stir plate, and let the starter ferment and the cells rebuild their reserves. Are the cells going to be different (e.g. mutated? damaged?) compared to those in a non-stirred starter inoculated with a smack pack?

What is your goal?  You clearly seem to have an agenda. Here's a suggestion.  Why don't you run tests, measure the results, compile a report, and share it with us?    I am open to any new data.

dfhar

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Re: New starter procedure trial
« Reply #227 on: October 08, 2015, 03:47:44 AM »
There is a difference between ergosterol and UFA levels between high krausen and quiescent cells.

Yes, but by how much? Is this measurable? After two days on a stir plate, will my yeast have 98% as much nutrients in reserve as they did at high krausen? 75%? 50%? How big of a difference is significant for fermentation performance, given the fact that these same nutrients are going to be available in 20x more quantity in the wort the yeast will be pitched into?

Kai Troester also did some experiments where he showed that high stir plate speed significantly increased the number of cells grown in the same starter culture when compared to a low speed with no vortex (http://braukaiser.com/blog/blog/2013/03/25/stir-speed-and-yeast-growth/). Presumably, a non-stirred starter would grow the same number or fewer cells than the low speed starter. If I grew X number of cells using a James Bond starter, and 2*X cells using a stir plate starter, but the stir plate starter cells had 50% as many nutrients in reserve as the James Bond cells, what difference in fermentation performance can I expect, given that after a single replication period, the James Bond cells would be at 50% reserves and number at 2*X?

I'm also wondering whether shear stress can cause permanent damage to a culture. Let's say I grew a culture on a stir plate, cold crashed it, then decanted the spent wort. Then I added fresh wort, removed the stir plate, and let the starter ferment and the cells rebuild their reserves. Are the cells going to be different (e.g. mutated? damaged?) compared to those in a non-stirred starter inoculated with a smack pack?

What is your goal?  You clearly seem to have an agenda. Here's a suggestion.  Why don't you run tests, measure the results, compile a report, and share it with us?    I am open to any new data.

Please don't get offended. I do not have an agenda, and my goal is simply to brew the best beer possible. These are completely honest questions that I am curious to know the answers to. I have been making my starters on a stir plate, and if I could make better beer using a different method I would like to learn about that method.
« Last Edit: October 08, 2015, 03:52:43 AM by dfhar »

S. cerevisiae

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Re: New starter procedure trial
« Reply #228 on: October 08, 2015, 05:05:52 AM »
Please don't get offended. I do not have an agenda, and my goal is simply to brew the best beer possible. These are completely honest questions that I am curious to know the answers to.

First off,  ergosterol and UFAs are synthesized during the lag phase by shunting carbon and O2 to the respirative metabolic pathway.   The lower these compounds are when the cells are pitched, the higher the initial O2 load and the longer the lag phase because these reserves have to be rebuilt.  That lag time increase is in addition to the time that it takes the cells to reverse the survival-related morphological changes that they underwent at the end of fermentation. You do not have take my word for it.  All you have to do is search for publications that cover the lag phase, O2 usage, and/or ergosterol and UFA synthesization in Saccharomyces cerevisiae or Saccharomyces pastorianus.  You may have to read more than one publication to obtain the core of the knowledge that you seek.

Secondly, it appears that you may have not taken the time to read the entire thread and the entire "Shaken, not stirred lager starter" thread.  If you had taken the time to read both threads, you would have known that absolute cell count is not the overall determining factor when pitching propagated yeast.  Have you ever smelled a starter that was spun fast enough to create vortex?  That smell is not oxidation.  It's stress.  The geometry of an Erlenmeyer flask prevents O2 from entering the flask after the culture starts outgassing.  Additionally, the reason why a vortex is required is due to the tiny amount of surface area and head space that is available in a 2L Erlenmyer flask that contains 1L of starter wort.  A gas (O2 in this case) dissolves into a liquid at the interface between the gas and the liquid.  The vortex increases the media surface area.  It also creates a vacuum that pulls air into the flask.  How much air the vortex pulls into the flask depends on its strength as well as how open to the flask is to the outside world.

A  "Shaken, not stirred" starter is not your typical non-stirred, non-forced O2 starter.  It takes advantage of physics and chemistry to create a massive amount of surface area.  A gas-liquid foam has a very high specific surface area.  A gas-liquid foam is pockets of gas enclosed by thin layers of liquid.  A vortex does not come remotely close to producing the same amount of surface area produced when the shaking procedure is properly executed because there is no way to match it with a gas-liquid two-phase system.   Once in gas-liquid foam form, chemistry takes care of the rest based on Henry's law (see http://www.800mainstreet.com/9/0009-006-henry.html).

One thing that is still not clear is the interaction between the O2 in the trapped air and the yeast cells that are on the surface of the thin layers of liquid that entrap the air if the culture is pitched before shaking.  That arrangement makes available 21 parts per hundred O2, not 8ppm O2.

Finally, there are no "cookbook" answers when dealing with yeast cultures.  Yeast cells are biological organisms that we can only steer during propagation and fermentation.  No two strains behave exactly the same when pitched into a wort (No strain behaves exactly the same way when pitched in two different breweries). If they did, they would produce the same beer given identical worts.  Anyone who has ever split a batch between two different strains has experienced different results from the same wort.  Some cultures will behave beautifully when pitched at a rate 3 billion cells per liter and produce a lackluster beer when pitched at 10 billion cells per liter.  Other strains need higher pitching rates to perform their best.  They way that you personally are going to be able to compile the data that you seek is to experiment with the stains in question and take very good notes.  You can be assured that professional brewers no exactly how there house yeast will perform when pitched.  That knowledge comes from repeated use.
« Last Edit: October 08, 2015, 03:53:59 PM by S. cerevisiae »

evil_morty

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Re: New starter procedure trial
« Reply #229 on: October 08, 2015, 10:41:02 AM »
alright - I'm all prepped to mash in and make a starter tonight after the kids are in bed.  Just to review...

10 gal of 1.051 lager (WL833)
2L starter with 200g of light DME, fermented at room temp (high 60s), in a 5 gal better bottle (lots of head space!)
Starter will probably be shaken around 8:30-9:00PM.  The next day I'll probably have chilled wort before lunch.

I will shake it as much as I can with the yeast in there.  Should I be able to fill most of the better bottle with foam or is that too ambitious?

Offline mabrungard

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Re: New starter procedure trial
« Reply #230 on: October 08, 2015, 01:19:10 PM »
Mark, I don't think a vortex in the starter wort surface is going to create a vacuum that could draw air in from outside the flask. That would require some sort of magic. The vortex could help spin the air column above the wort, but not move air into the vessel. That conservation of mass thing comes into play.

As pointed out, once yeast are actively outgassing CO2, the ability for atmospheric air to enter the vessel and provide O2 is reduced. That is the reason I recommend pumping filtered air into the vessel to assure that there is some O2 in the headspace that can be transferred into the wort.

In my opinion, a vortex is not really needed when the headspace has a constant supply of atmospheric oxygen. I stir my wort only to the degree necessary to keep the cells in suspension. That is more like the shaken technique that Mark recommends.
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Offline denny

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Re: New starter procedure trial
« Reply #231 on: October 08, 2015, 02:52:50 PM »
Cheap and easy is great, but even Denny has a stir plate.  Many of us are looking for the best method that's practical.  Modern homebrewers wouldn't think twice about getting a disposable O2 tank and cheap "regulator" (the valve that williams sells that doesn't include an actual regulator) if it were significantly better or easier.  You don't need an oxygen tank and welding regulator, but it saves money and makes things repeatable.  However, for a starter it sounds like that doesn't matter.  Saturate it and let 'er rip!

Just to clraify, I have a stir plate because I was given one that was going to be thrown away otherwise.  If that hadn't happened, I'd likely never have gotten one.
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Re: New starter procedure trial
« Reply #232 on: October 08, 2015, 03:51:34 PM »
Mark, I don't think a vortex in the starter wort surface is going to create a vacuum that could draw air in from outside the flask. That would require some sort of magic. The vortex could help spin the air column above the wort, but not move air into the vessel. That conservation of mass thing comes into play.

I am basing that assumption on the fact that a vortex has an area of low pressure at its core.  Granted, any air coming into the flask has to displace something already in the flask.  However, that being said, I do not believe that the answer is simple.  If people are reporting increased cell growth with a vortex, then some physical phenomenon or phenomena is/are occurring.  Part of the equation can be attributed to an increase in the size of gas-liquid interface.  However, it does not explain everything because there is a limited amount gas in the of head space of an Erlenmeyer flask that is 50%+ full, which leads me to believe that there is gas exchange occurring between the inside and the outside of the flask before the culture starts to outgas.  Even if the exchange is caused by the spinning of the air above the wort.  It has to be causing an air current of some kind.

Offline dilluh98

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Re: New starter procedure trial
« Reply #233 on: October 08, 2015, 03:55:09 PM »
For my next larger batch I'm going to split the wort and try the two iterations of 'shaken not stirred' and see what happens. My gut tells me it's not going to matter one way or the other but that's why we experiment.

(1) Shake, then add yeast.

(2) Add yeast, then shake.


S. cerevisiae

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Re: New starter procedure trial
« Reply #234 on: October 08, 2015, 03:57:21 PM »
Just to clarify, I have a stir plate because I was given one that was going to be thrown away otherwise.  If that hadn't happened, I'd likely never have gotten one.

I would say that that meets the definition of cheap.

Offline a10t2

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Re: New starter procedure trial
« Reply #235 on: October 08, 2015, 04:22:00 PM »
In my opinion, a vortex is not really needed when the headspace has a constant supply of atmospheric oxygen. I stir my wort only to the degree necessary to keep the cells in suspension. That is more like the shaken technique that Mark recommends.

Same here.
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Offline denny

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Re: New starter procedure trial
« Reply #236 on: October 08, 2015, 04:36:30 PM »
Just to clarify, I have a stir plate because I was given one that was going to be thrown away otherwise.  If that hadn't happened, I'd likely never have gotten one.

I would say that that meets the definition of cheap.

AND pragmatic!  :)
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Offline MerlinWerks

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Re: New starter procedure trial
« Reply #237 on: October 08, 2015, 04:43:34 PM »
OK, I have ~700ml of 4th gen WY1450 ;) that is 2 weeks old sitting in my fridge under beer. I would like to try the "SNS" method this weekend.

What would be a good starting volume of slurry?

Gently stir up the whole 700ml straight from the fridge, remove the starting volume and inoculate the 1L?

Thanks!

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Re: New starter procedure trial
« Reply #238 on: October 08, 2015, 04:53:37 PM »
I stir my wort only to the degree necessary to keep the cells in suspension.

As I have mentioned before, brewing yeast strains generally do not need to be stirred to remain in suspension because they exhibit NewFlo flocculation.  If they are settling out, then the carbon level in the medium is very low.  The only value added by stirring is that stirring helps to degas the culture, which should already be under minimal top pressure.

Wyeast's site claims that ale strains are Flo1, but that claim goes against most of the published data.  Flo1 strains are unusable in brewing without continuous stirring because they drop out of suspension too early.

Quote
That is more like the shaken technique that Mark recommends.

No, it is still a stirred starter.

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Re: New starter procedure trial
« Reply #239 on: October 08, 2015, 05:06:11 PM »
OK, I have ~700ml of 4th gen WY1450 ;) that is 2 weeks old sitting in my fridge under beer. I would like to try the "SNS" method this weekend.

Unless you are looking for an intellectual exercise, I would pitch the slurry straight.  You have more than enough cells to get the job done, regardless of their condition.

With that said, you need at most 100ml of thick slurry for a 1L starter, and I wouldn't pitch that much.  I would pitch more like 65ml of thick slurry.  That volume should contain roughly 60 billion viable cells at two weeks.  A 10% w/v (1.040) starter should provide enough carbon to reach or approach maximum cell density, with a 2-to-1 new to old cell ratio.