Shaken, not Strirred

Share your experiences of using brewing yeast.
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YeastWhisperer

Re: Shaken, not Strirred

Post by YeastWhisperer » Tue Aug 18, 2015 3:39 pm

McMullan wrote:[
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.
You are acting like there is a ton of evidence that supports the use of stir plates when propagating brewing yeast cells. The little evidence that does exist is the work of home brewers, and it is usually based on a sample size of less than ten. Stir plate usage in the home brewing community is based on a misinterpretation of research performed by Maribeth Raines in the nineties. I work for a life science research organization, and there is not a single stir plate being used for anything other than mixing. Orbital shakers, wrist-action shakers, and roller tables are used for suspension cell culturing in our labs.

Fact #1

Yeast cells need carbon and O2 to replicate

Fact #2

Brewing yeast cultures do not need to be stirred to remain in suspension in batch cultures because most brewing yeast strains exhibit NewFlo flocculation. NewFlo strains do not floc until glucose, mannose, sucrose, maltose, and maltotriose have reached genetically set levels.

Fact #3

Slowly stirring a culture whose volume displaces 50% of the volume of the Erlenmeyer flask in which it is being propagated does not provide much in the way of O2 absorption over a non-stirred culture of the same volume in the same flask because it does not increase the specific surface area of the gas-liquid interface. Spinning the medium fast enough to create a vortex does in fact increase O2 absorption, but it does so by a) increasing the gas-liquid specific surface area, and b) creating a vacuum that draws air into the vortex. Spinning a culture fast enough to create a vortex also increases the amount of shear stress placed on the cells. You can attempt to refute the shear stress claim, but the evidence does not support your thesis.

Truth be told, I did not set out to create a new method because an old method did not work. My method was a purely serendipitous event. I was propagating one U.S. quart starters in a forty-eight U.S. fluid ounce glass juice bottle. I went to make a starter and discovered that my juice bottle was cracked. I had a one U.S. gallon glass jug (demijohn in UK speak) on hand that I used to make small batches of mead that I decided to use as a quick fix to my problem. Shaking the culture until it was almost all foam was the result of being incredibly strong and in good cardiovascular shape from spending my teens through my mid-thirties in the gym. The difference in fermentation was immediately noticeable, so I kept using the method. I did not realize that shaking the starter until it was almost all foam resulted in a huge increase in specific surface area with respect to the gas-liquid interface until I revisited my university physics text a few years later.

Even with this knowledge, I switched to using a stir plate many years later based on the claims being published by other home brewers. The difference that I noticed right away was that my stirred cultures smelled off, which resulted in the requirement to decant the supernatant. The second thing that I noticed was an increase in fermentation metabolites that signaled stress. At first, I just wrote the differences in performance off as something that would take time to perfect. However, after a year of using a stir plate religiously, I decided to brew a double size batch for experimentation purposes. I wanted to see if the problem was real or if I had fallen victim to nostalgia. Well, that test confirmed that I was not being nostalgic. Wanting to see if my results were reproducible, I posted my method on a U.S.-based home brewing forum where it was met with the same level of doubting Thomasism that you have expressed; however, over time, more and more home brewers were reporting an improvement over using a stir plate. While some have switched from shaking to pure O2 injection in order to avoid the laborious task of shaking a starter extremely vigorously for a couple of minutes, I do not know of a single brewer who has tried the method that has gone back to using a stir plate. In fact, many have sold their stir plates. From reading this thread, it appears that several brewers in the UK have been able to repeat my results.
Last edited by YeastWhisperer on Wed Aug 19, 2015 12:23 am, edited 1 time in total.

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Re: Shaken, not Strirred

Post by Bazz » Tue Aug 18, 2015 4:09 pm

Not really wanting to stick my un-scientific nose in to your guys debate here but i have tried the shaken not stirred method as it allowed me to grow up a starter without having to invest in yet another piece of equipment for home brewing (stir plate), consequently i have absolutely no idea of how a starter made with a stir plate performs but what i can say is that the shaken not stirred method has proved very effective for me and has now become my go to method for creating a nice healthy starter, so thanks Yeastwhisperer, you have saved me a few quid :D

barry44

Re: Shaken, not Strirred

Post by barry44 » Tue Aug 18, 2015 4:37 pm

Bazz wrote:Not really wanting to stick my un-scientific nose in to your guys debate here but i have tried the shaken not stirred method as it allowed me to grow up a starter without having to invest in yet another piece of equipment for home brewing (stir plate), consequently i have absolutely no idea of how a starter made with a stir plate performs but what i can say is that the shaken not stirred method has proved very effective for me and has now become my go to method for creating a nice healthy starter, so thanks Yeastwhisperer, you have saved me a few quid :D
i agree fully with the above statement. I have used this method twice and it has worked perfectly.Again, i have never used a stirplate so cannot compare the two methods.

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Re: Shaken, not Strirred

Post by jaroporter » Tue Aug 18, 2015 5:20 pm

i got reallly unsatisfactory results when using a stirplate, and stopped using liquid yeast for ages as a result, thinking it was a pain in the ass not worth the risk. i got similar experiences to YeastWhisperer is his last post. never really attributed it to that until i saw this but it makes sense. tried this out, only a few goes in but the difference is marked. so i wont claim it's a fair comparism yet, but the logic is sound and the results promising. cheers again for the post and the reasoning.
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Re: Shaken, not Strirred

Post by Goulders » Tue Aug 18, 2015 5:33 pm

@YeastWhisperer: what is your method when stepping up from slants?

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Re: Shaken, not Strirred

Post by McMullan » Tue Aug 18, 2015 6:11 pm

YeastWhisperer wrote:
McMullan wrote:[
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.
You are acting like there is a ton of evidence that supports the use of stir plates when propagating brewing yeast cells. The little evidence that does exist is the work of home brewers, and it is usually based on a sample size of less than ten. Stir plate usage in the home brewing community is based on a misinterpretation of research performed by Maribeth Raines in the nineties. I work for a life science research organization, and there is not a single stir plate being used for anything other than mixing. Orbital shakers, wrist-action shakers, and roller tables are used for suspension cell culturing in our labs.


Fact #1

Yeast cells need carbon and O2 to replicate

Fact #2

Brewing yeast cultures do not need to be stirred to remain in suspension in batch cultures because most brewing yeast strains exhibit NewFlo flocculation. NewFlo strains do not floc until glucose, mannose, sucrose, maltose, and maltotriose have reached genetically set levels.

Fact #3

Slowly stirring a culture whose volume displaces 50% of the volume of the Erlenmeyer flask in which it is being propagated does not provide much in the way of O2 absorption over a non-stirred culture of the same volume in the same flask because it does not increase the specific surface area of the gas-liquid interface. Spinning the medium fast enough to create a vortex does in fact increase O2 absorption, but it does so by a) increasing the gas-liquid specific surface area, and b) creating a vacuum that draws air into the vortex. Spinning a culture fast enough to create a vortex also increases the amount of shear stress placed on the cells. You can attempt to refute the shear stress claim, but the evidence does not support your thesis.

Truth be told, I did not set out to create a new method because an old method did not work. My method was a purely serendipitous event. I was propagating one U.S. quart starters in a forty-eight U.S. fluid ounce glass juice bottle. I went to make a starter and discovered that my juice bottle was cracked. I had a one U.S. gallon glass jug (demijohn in UK speak) on hand that I used to make small batches of mead that I decided to use as a quick fix to my problem. Shaking the culture until it was almost all foam was the result of being incredibly strong and in good cardiovascular shape from spending my teens through my mid-thirties in the gym. The difference in fermentation was immediately noticeable, so I kept using the method. It did not realize that shaking the starter until it was almost all foam resulted in a huge increase in specific surface area with respect to the gas-liquid interface until I revisited my university physics text a few years later.

Even with this knowledge, I switched to using a stir plate many years later based on the claims being published by other home brewers. The difference that I noticed right away was that my stirred cultures smelled off, which resulted in the requirement to decant the supernatant. The second thing that I noticed was an increase in fermentation metabolites that signaled stress. At first, I just wrote the differences in performance off as something that would take time to perfect. However, after a year of using a stir plate religiously, I decided to brew a double size batch for experimentation purposes. I wanted to see if the problem was real or if I had fallen victim to nostalgia. Well, that test confirmed that I was not being nostalgic. Wanting to see if my results were reproducible, I posted my method on a U.S.-based home brewing forum where it was met with the same level of doubting Thomasism that you have expressed; however, over time, more and more home brewers were reporting an improvement over using a stir plate. While some have switched from shaking to pure O2 injection in order to avoid the laborious task of shaking a starter extremely vigorously for a couple of minutes, I do not know of a single brewer who has tried the method that has gone back to using a stir plate. In fact, many have sold their stir plates. From reading this thread, it appears that several brewers in the UK have been able to repeat my results.
:^o it's not me acting like there's a 'tonne of evidence', is it? By the way, there's no such thing as a 'fact', scientifically speaking. Perhaps you should back up your claims with some credible data in future?

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Re: Shaken, not Strirred

Post by McMullan » Tue Aug 18, 2015 6:49 pm

A stir plate should be used to provide a little agitation to a yeast starter, as I've written elsewhere. An orbital shaker is what would be used in a research lab, but they are not as affordable to the average home brewer as a stir plate. The stir plate is a great substitute, if used with a little common sense...

Wezzel

Shaken, not Strirred

Post by Wezzel » Tue Aug 18, 2015 7:09 pm

I can understand people being protective of their stir plate especially if they have lovingly built it and used it successfully over many brews but, hey, if this method works let's embrace it as another tool in the box.

I've could never be bothered to make a stir plate but I can definitely see me using the shake method for its simplicity

YeastWhisperer

Re: Shaken, not Strirred

Post by YeastWhisperer » Wed Aug 19, 2015 2:59 am

[
McMullan wrote:An orbital shaker is what would be used in a research lab, but they are not as affordable to the average home brewer as a stir plate.
I own a Lab Line 3520 Orbital Shaker as well as a Hanna HI 190M stir plate. It cost me the grand sum of $150.00US.

Image

It is a well-built device. Here are a couple of photos that I shot of the guts of the machine:

Image[/URL]

Image

Image

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Re: Shaken, not Strirred

Post by Jocky » Wed Aug 19, 2015 7:49 am

YW has one thing right - stirred starters don't smell right, whereas the shaken ones I've done so far (3) have been normal smelling for the yeast type.

I don't know whether that's down to oxidation of the starter or yeast autolysis or something else, but it is a factor in me being happier with this method over using a stir plate.

The only evidence I've seen in support of a stir plate is that you seem to be able to get a greater cell count over other methods, but I haven't seen anything that shows the relative health of those cells. If someone wants to organise an experiment I'm more than happy to participate.
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Re: Shaken, not Strirred

Post by Aleman » Wed Aug 19, 2015 7:58 am

I used a stir plate simply because my batch length was 90L. I decanted the supernatant and pitched. I have some seriously out of date tubes that I will use the stir plate for. Then use the shaken method on the slurry before pitching.

One benefit of the Braumeister that I didn't foresee was making starters became so much easier.

barry44

Re: Shaken, not Strirred

Post by barry44 » Wed Aug 19, 2015 8:05 am

Aleman wrote:
One benefit of the Braumeister that I didn't foresee was making starters became so much easier.
Aleman, can you explain this further?

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Re: Shaken, not Strirred

Post by McMullan » Wed Aug 19, 2015 8:32 am

YeastWhisperer wrote:[
McMullan wrote:An orbital shaker is what would be used in a research lab, but they are not as affordable to the average home brewer as a stir plate.
I own a Lab Line 3520 Orbital Shaker as well as a Hanna HI 190M stir plate. It cost me the grand sum of $150.00US.
Bargain! I tried getting one on eBay from the states. Postage and import quote was more than the shaker. I might go for a Chinese?

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Re: Shaken, not Strirred

Post by McMullan » Wed Aug 19, 2015 8:40 am

Jocky wrote:YW has one thing right - stirred starters don't smell right, whereas the shaken ones I've done so far (3) have been normal smelling for the yeast type.

I don't know whether that's down to oxidation of the starter or yeast autolysis or something else, but it is a factor in me being happier with this method over using a stir plate.

The only evidence I've seen in support of a stir plate is that you seem to be able to get a greater cell count over other methods, but I haven't seen anything that shows the relative health of those cells. If someone wants to organise an experiment I'm more than happy to participate.
I've read that a number of Brewers complain about the smell and taste of stirred starters. I assumed excessive speed to create Atlantic size whirlpools was promoting oxidation. My stirred starters smell fine, but they are stirred at very low speed.

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Re: Shaken, not Strirred

Post by Aleman » Wed Aug 19, 2015 9:15 am

McMullan wrote:
Jocky wrote:YW has one thing right - stirred starters don't smell right, whereas the shaken ones I've done so far (3) have been normal smelling for the yeast type.
I've read that a number of Brewers complain about the smell and taste of stirred starters. I assumed excessive speed to create Atlantic size whirlpools was promoting oxidation. My stirred starters smell fine, but they are stirred at very low speed.
+1 :thumb:

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