[Wilbur]

Since Chris White has been brought into this, I'll quote what he said to me when I told him about the SNS method....."that's great!  Homebrewers are too hung up on numbers"

I agree, if you read his book and look at some of the stuff Escarpment and others have put out, it's pretty clear that yeast requirements are pretty broad. My only point was the idea that there's no precedent or authority suggesting the use of a stir plate isn't really true.

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[Saccharomyces]

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[Saccharomyces]

@wilbur

I does appear that I have somehow slapped your proverbial puppy. I do not know if you are being obtuse or you are incapable of understanding what I have written because your counter argument is disjointed and your understanding of gas exchange and SNS is lacking. First off, nowhere  in the description of my method do I state that the starter needs to be shaken periodically. I challenge you to find any text where I make claim. Secondly, CO2 naturally comes out of solution at room temperature. Anyone who has pulled an over-gassed pint from a cold keg has experienced the massive foaming that occurs as CO2 gas rapidly comes out of solution. The only way to prevent out gassing at room temperature is via pressure.  A starter continues to outgas CO2 even when a airlock is attached.  However, nowhere in my method do I discuss using an air lock. I have always used a container that has a screw-on cap. All one has to do after shaking is loosen the cap.

As far to the use of an impeller in a bioreactor, that is not the way it is used in continuous propagation.  The impeller is not used as much to drive off CO2 as it is to keep the medium at a steady state (Google “steady state condition”). Yeast and spent medium are continuously drawn off on the discharge end while new medium and O2 are continuously added to the process on the intake end; therefore, CO2 has a way to escape solution.

In the end, no one in this thread has mentioned that you need to switch propagation methods, no one. This thread has been about the belief that stir plates are the best way to make starters being myth. On the other, you joined the discussion apparently itching for a fight. As I mentioned above, it is like I slapped your proverbial puppy when all I did was present facts that are backed up by peer-reviewed science, science that has stood the test of time and has been built upon by other professional scientists. I have been studying brewing yeast for a long time, seriously for at least a decade. I brewed almost exclusively with yeast I isolated and maintained on agar slants for my first and second passes through the hobby, which means I have a pretty good understanding of yeast management. I did not start out to prove that stir plate mania was myth.  It is just that as an INTJ (Myers-Briggs type), I have an insatiable thirst for knowledge. Brewing yeast has fascinated me for close to thirty years. The results that I achieved using a stir plate did not align with the hype, given my previous experience with other methods. That is what caused me to question the use of stir plates in the amateur brewing community.

[Saccharomyces]

My only point was the idea that there's no precedent or authority suggesting the use of a stir plate isn't really true.

One last thing, there is zero precedent outside of the amateur brewing community for the use of stir plates, zero.  The problem with using amateur brewing as a president is inherent bias. When all one has ever used to make a starter is a stir plate outside of just pitching a culture into starter wort, one is working from a scientifically myopic point of view. Your insistence that agitation is need to release CO2 is a prime example of this phenomenon in brewing at the amateur level.  CO2 removal is not as critical as O2 in propagation and O2 pickup is a function of specific surface area, that is, when not using direct CO2 injection.
 
Maybe, it is because I survived having my research tested in graduate school (it was brutal), but my approach has been to continuously read new publications to see if previous research has been rendered obsolete by new research. I find that only a small proper subset of amateur brewers have this type mindset, most, but not all, have been with the hobby for a long time. These people are lifelong learners.

[Wilbur]

Hey bud, I'm not taking offense to anything. You posted an article, I'm engaging in discussion. Almost as if I was on a forum. I thought I'd add some constructive criticism, and you told me to Google things. So I did.

My knowledge of gas dynamics is pretty good. I do not claim that CO2 will not come out of solution. Some will, and some won't. My point is that above certain concentrations, CO2 will slow yeast growth. This is widely documented in scientific research.

My other point on CO2 is that it will not form a blanket if there is fluid/gas in motion. This motion occurs precisely because CO2 is off gassing. Until there is enough CO2 being produced by the yeast to produce a positive pressure effect, oxygen will continue to be present in the atmosphere in the starter. It seems self evident that there's not enough active yeast at pitch to create that condition. I don't care for myths either, so I didn't want to let the CO2 blanket myth stand.

I never claimed bio reactors had impellers. I'm not sure where that came from.

I think I've made it pretty clear that I don't have a problem with SNS or stir plates, and in the end I'm not drinking your beer anyway. I just like talking about brewing.

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[Saccharomyces]

My other point on CO2 is that it will not form a blanket if there is fluid/gas in motion. This motion occurs precisely because CO2 is off gassing. Until there is enough CO2 being produced by the yeast to produce a positive pressure effect, oxygen will continue to be present in the atmosphere in the starter. It seems self evident that there's not enough active yeast at pitch to create that condition. I don't care for myths either, so I didn't want to let the CO2 blanket myth stand.

Please point to the post where I used the word "blanket."  I used the term "positive pressure."  As long as there is positive pressure from off-gasing, spinning a culture to aerate it during active fermentation is a stretch, especially in a cone, which concentrates the pressure of the escaping CO2 while minimizing the amount of specific surface area where O2 pickup can occur.  CO2 molecules are heavier than O2 molecules.  That is easy to see because CO2 contains a carbon atom in addition to oxygen atoms.  While O2 reaching the surface is possible while CO2 is being expelled, there will not be much of it.  It is law of partial pressures. Unless something is done to increase the pressure in the headspace of the propagation vessel, CO2 will continue to come out of solution.  The escaping CO2 will eventually diffuse, but it will remain in at a high enough level to make O2 ingress difficult because, once again, CO2 is heaver than O2.

The reality it that I would not have written the blog entry if I did not have my ducks in a row because I expected stir plate myth believers to come at me like a hungry pack of wolves.  It takes a lot of courage and solid set of facts to claim that the emperor has no clothes.  You claim to want to engage in constructive criticism, but what I see, and I sure others do, is someone who has taken an aggressive stance on shutting down the discussion.  Once again, if you are happy with your starter method, keep it.  However, I seriously doubt that you have tried my method because a) you would know that the culture is only shaken to introduce O2 one time and b) it is much simpler than using a stir plate. One cannot beat pouring boiled media into a sanitized jug, capping the jug with a sanitized screw-on cap, shaking the bejesus out of it, pitching a culture, putting screw-cap back on the jug, gently shaking the starter to disperse the cells, loosening the cap to allow CO2 gas to escape, waiting 12 to 18 hours, and then pitching the entire contents of the starter.  It is that simple and the results are repeatable. 

The reality is that I did not twist anyone's arm to switch from using a stir plate to using my method because I know that old habits die hard.  It is easy for a process or procedure to become ingrained.  I received a lot of push-back on this forum when I originally posted my method close six years ago.  People could not believe that something so simple and cheap could work as well as it does.  I left the hobby for a little under four years due to family issues.  What brought me back was that I was astonished to see how many people had adopted my method of making a starter world-wide, most of whom are not active in this forum.  I literally could not believe it.  That was when I realized that the hobby still had people with open minds.  Homebrewing dogma cripples our hobby. The stir plates produce superior cultures to all other methods myth is homebrewing dogma.

[Wilbur]

You're saying I'm aggressive but you cast doubts on if I've tried your method? Have a nice day sir, I am done.

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[Kevin]

... I have always used a container that has a screw-on cap. All one has to do after shaking is loosen the cap

And don't forget this step. And by all means don't forget this step and then several hours later, when ready to pitch, swirl the contents before remembering to loosen the cap. Don't ask me how I know. 

[waltsmalt]

Really want to give this method a shot with my next brew.  It’s a Belgian IPA, 1.059 OG, and a 10 gallon batch.  All of the beer will be fermented in a single fermentor.  So, if I’m reading this right, I should just: take two 1 gallon jugs, two yeast packets, and make a 1 quart starter.  Then I should just pitch both in the 10 gallon batch.  All done 24 hours or so prior to brewing.  Sound right?  Did I miss anything?

[pete b]

Really want to give this method a shot with my next brew.  It’s a Belgian IPA, 1.059 OG, and a 10 gallon batch.  All of the beer will be fermented in a single fermentor.  So, if I’m reading this right, I should just: take two 1 gallon jugs, two yeast packets, and make a 1 quart starter.  Then I should just pitch both in the 10 gallon batch.  All done 24 hours or so prior to brewing.  Sound right?  Did I miss anything?

Sounds right, assuming you mean two one quart starters, one for each gallon jug, it’s that simple. Really, the only tricky part is timing the high krausen with the time you are ready to pitch and there is definitely wiggle room. As with anything that involves living organisms you need to be prepared to be flexible and react to the critters timing. You are a steward not a master.

[Saccharomyces]

Sounds right, assuming you mean two one quart starters, one for each gallon jug, it’s that simple. Really, the only tricky part is timing the high krausen with the time you are ready to pitch and there is definitely wiggle room. As with anything that involves living organisms you need to be prepared to be flexible and react to the critters timing. You are a steward not a master.

One thing I have learned from growing and maintaining a sourdough culture as well as making sourdough is that if a starter looks like it is going to crest too soon (e.g., the onset of low krausen), one can just place the starter in one's refrigerator (just remember to pull it out of the refrigerator at least an hour before pitching.  Fermentation will not stop.  It will just slow to a crawl.  The process is known as "retarding fermentation."  For example, a sourdough culture kept at room temperature needs to be fed every day.  However, if one feeds a mature sourdough culture and then places it in a refrigerator, the feeding interval can be pushed to at least five days.  I recommend retarded fermentation to another forum member who schedule made a 12 to 18 hour pitching interval too short.  It worked so well that he gave it another name. 

[Richard]

I recommend retarded fermentation to another forum member who schedule made a 12 to 18 hour pitching interval too short.  It worked so well that he gave it another name.

Yeah, that was me. When I was trying to come up with a clever name my wife, who is a nurse, told me not to use the word "retarded". I used the phrase "refrigerator delayed" instead. I called it SNS The Next Generation: PICARD (Pitched In Container And Refrigerator Delayed).

[pete b]

Is it accurate to say that refrigerating needs to happen at least just before high krausen at the latest?

[Saccharomyces]

Is it accurate to say that refrigerating needs to happen at least just before high krausen at the latest?

Yes, retarding the fermentation should occur before high krausen is reached.  Low krausen (when patches of foam start to appear on the surface) is about the latest that I would recommend retarding the fermentation. The reality is that different strains proceed at different paces.

[kpfoleyjr]

I've been using a stir plate for a while, and want to try the SNS method.  I normally use Wyeast and brew 5 to 6-gallon batches.  I wanted to know what others think of this as a plan to follow.  Excuse the detail; i have Engineer disease.

1) Put about a liter (or whatever amount BeerSmith3 indicates, depending upon the age of the yeast packet) of boiled and cooled Briess Golden Light dry malt extract and RO water with a gravity of about 1.035 into a sanitized glass container.  This would typically be done the day before brewing.
2) Place a sanitized stopper on the container and shake it vigorously to aerate the starter wort.  (I used to add oxygen, but will not for the SNS).
3) Pitch the sanitized yeast packet into the wort while it's within the correct pitching temperature range.  Swirl the mixture to mix it thoroughly.
4) Use a sanitized airlock and stopper to close off the container.  Watch for the peak in bubbling at the airlock, and foam on top of the mixture, to determine when it's at high Krausen.
5) Replace the airlock with a piece of sanitized aluminum foil at high Krausen, and move the container to a 40 degree refrigerator to slow down the yeast action.
6) In a day or two, on brew day, remove the container from the refrigerator and allow the starter to rise to room temperature.
7) Add oxygen to the brewing wort.  Swirl the starter mixture to suspend the sediment on the bottom, then pitch the entire content into the brewing wort.

Anything incorrect in my thinking?  Anything missing?  Any step that could be made easier by eliminating something that's unnecessary?