Shaken, not Strirred

Share your experiences of using brewing yeast.
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YeastWhisperer

Re: Shaken, not Strirred

Post by YeastWhisperer » Mon May 25, 2015 4:16 pm

barry44 wrote:Pitched in. One thing I'm now thinking about is whether there was enough yeast in the slurry, 1st time rinsing and reusing.
I would not worry the amount of yeast. I would worry about the amount of contamination that you may have picked up during rinsing. Rinsing yeast with water is not a biologically sound practice.

barry44

Re: Shaken, not Strirred

Post by barry44 » Tue May 26, 2015 8:07 am

Checked last night and we were off!!

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Jocky
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Re: Shaken, not Strirred

Post by Jocky » Tue Jul 28, 2015 11:26 am

A 1 litre starter in a 5 litre plastic bottle, post shaking:
image.jpg
Pretty sure that's well aerated.
Ingredients: Water, Barley, Hops, Yeast, Seaweed, Blood, Sweat, The swim bladder of a sturgeon, My enemies tears, Scenes of mild peril, An otter's handbag and Riboflavin.

barry44

Re: Shaken, not Strirred

Post by barry44 » Tue Aug 04, 2015 1:33 pm

Jocky,

how long after shaking did you pitch the starter?

YeastWhisperer

Re: Shaken, not Strirred

Post by YeastWhisperer » Tue Aug 04, 2015 2:54 pm

Jocky wrote:A 1 litre starter in a 5 litre plastic bottle, post shaking:
image.jpg
Pretty sure that's well aerated.
Holy smokes! That starter was shaken with a purpose. You pretty much maxed out the gas-liquid interface.

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Jocky
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Re: Shaken, not Strirred

Post by Jocky » Tue Aug 04, 2015 3:15 pm

barry44 wrote:Jocky,

how long after shaking did you pitch the starter?
I can't remember for that brew (which turned out excellent from a fermentation point of view), but it will be 20-24 hours after shaking. By that time there is a reasonable krausen to know I have very active, healthy cells that have got out of the adaptive phase and done most of their replication and are ready to taken on a much larger task. I don't measure high krausen, I just check that there is some krausen.

By doing it on that timescale I can also make sure I have active yeast before I start brewing - if there's no activity I can postpone the brew day. If the starter subsequently does start (this hasn't happened yet - I'm 2/2 for active fermentation within 20 hours with YW's SNS method) then I can let it ferment, check it hasn't gone bad, and chill the whole thing in the fridge until I can brew, feeding it to wake everything up again if required.
Ingredients: Water, Barley, Hops, Yeast, Seaweed, Blood, Sweat, The swim bladder of a sturgeon, My enemies tears, Scenes of mild peril, An otter's handbag and Riboflavin.

barry44

Re: Shaken, not Strirred

Post by barry44 » Thu Aug 06, 2015 1:36 pm

thanks Jocky

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Cpt.Frederickson
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Re: Shaken, not Strirred

Post by Cpt.Frederickson » Fri Aug 07, 2015 2:57 pm

This is a truly superb post. May I suggest this is 'stickied' by one of our mods please?
The Hand of Doom Brewery and Meadery
Fermenting -
Conditioning - Meads - Raspberry Melomel yeast test, Vanilla Cinnamon Metheglyn, Orange Melomel.
Drinking - Youngs AAA Kit; Leatherwood Traditional Mead, Cyser, Ginger Metheglyn.
Planning - Some kits until I can get back to AG, then a hoppy porter, Jim's ESB, some American Red.

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Re: Shaken, not Strirred

Post by McMullan » Sat Aug 08, 2015 8:28 pm

I need some data to consider why I should shake and not stir. I've done a Google search, as someone recommended, but I didn't buy it myself. I'm not saying shaking it doesn't work. I'm saying stirring works. Very well in my experience.

barry44

Re: Shaken, not Strirred

Post by barry44 » Sun Aug 16, 2015 5:13 pm

ive just used this method for a second time, pitching a harvested WLP001 first gen.

I'll post once it is underway.

YeastWhisperer

Re: Shaken, not Strirred

Post by YeastWhisperer » Mon Aug 17, 2015 2:52 pm

McMullan wrote:I need some data to consider why I should shake and not stir. I've done a Google search, as someone recommended, but I didn't buy it myself. I'm not saying shaking it doesn't work. I'm saying stirring works. Very well in my experience.

If what you are doing works for you, then stick with it. However, my method is based on sound science. Nothing creates a better gas-liquid interface than foam. There is a large body of evidence that supports pitching at high krausen.

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Re: Shaken, not Strirred

Post by McMullan » Mon Aug 17, 2015 3:36 pm

YeastWhisperer wrote:
McMullan wrote:I need some data to consider why I should shake and not stir. I've done a Google search, as someone recommended, but I didn't buy it myself. I'm not saying shaking it doesn't work. I'm saying stirring works. Very well in my experience.

If what you are doing works for you, then stick with it. However, my method is based on sound science. Nothing creates a better gas-liquid interface than foam. There is a large body of evidence that supports pitching at high krausen.
'Sound science'? Whose? Biologists working with yeast don't create that much foam in their cultures, as far as I can remember. Perhaps they, like home brewers, are 'doing it wrong'? As I've written before, I use a stirrer because it makes the starter process more efficient (quicker). That fits well into my schedule. Until I made a stir plate, I used to swirl the yeast into the starter wort and let it incubate for a few days. It worked fine. Horses for courses, I guess.

barry44

Re: Shaken, not Strirred

Post by barry44 » Mon Aug 17, 2015 4:00 pm

it was away this morning less than 24 hours after pitching.

YeastWhisperer

Re: Shaken, not Strirred

Post by YeastWhisperer » Mon Aug 17, 2015 11:34 pm

McMullan wrote: 'Sound science'? Whose? Biologists working with yeast don't create that much foam in their cultures, as far as I can remember. Perhaps they, like home brewers, are 'doing it wrong'? As I've written before, I use a stirrer because it makes the starter process more efficient (quicker). That fits well into my schedule. Until I made a stir plate, I used to swirl the yeast into the starter wort and let it incubate for a few days. It worked fine. Horses for courses, I guess.
Do you agree that physics and chemistry are branches of natural science? 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.
Last edited by YeastWhisperer on Tue Aug 18, 2015 1:25 pm, edited 1 time in total.

McMullan
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Re: Shaken, not Strirred

Post by McMullan » Tue Aug 18, 2015 10:08 am

YeastWhisperer wrote:Do you agree that physics and chemistry are branches of natural science? 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 dues to 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 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 a very slow rate 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 in 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 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.
By 'quiescent' I assume you refer to the G0 phase? Or in plain English, a resting/dormant state. This is a perfectly normal state to be in for most living animal, plant and fungi cells. It's rapidly reversible too. As I wrote elsewhere, I observe evidence for this within 12 hours (max) of pitching my 'quiescent' starters into fresh worts.

It's not acceptable, scientifically, to simply extrapolate from basics about the physical and chemical nature of a foam, especially when there's a biological (yeast) component involved. This is not sound science. It's quite the opposite, actually. It's crystal ball gazing. If you want to prescribe a different way for preparing starters, you first need to provide convincing evidence that the current method of choice (a stir plate) is inferior. Assuming any relevance between a patent associated with reducing theoretical cell membrane 'shear stress' in bioreactors and a yeast starter prepared on a stir plate is crystal ball gazing for sure. You need to design experiments (or at least find some published ones) that specifically test your assumptions about home brew yeast starters. That would be more scientific.

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