The only culture that I have had to shake more than once is NCYC 1333, but NCYC 1333 is a class O3/O41 Yorkshire-square culture, meaning that its O2 demands can barely be met by wort that is saturated with pure O2. I suspect that most of the brewing strains that we use are either class O1 or class O2 (the O2 demands for class O1 strains can be met with wort that contains 4ppm dissolved O2 whereas class O2 strains require 8ppm). I know for certain that Whitbread “B” (Wyeast 1098, White Labs WLP007, and Fermentis S-04) is a class O2 strain because it is the same culture as NCYC 1026, and NCYC 1026 is a class O2 culture.
NCYC 1026
Information
Flocculent.
NewFlo type flocculation.
1:5:4:5:5 O2, DMS 33 µg/l, low acetic, high lactic, diacetyl 0.42ppm only, used commercially in Tower Fermenters (continuous process), non head-forming, no estery flavour. Contains 2µ plasmid.
Note: If anyone has ever wondered why Wyeast 1098 and WLP007 produce a slightly tart beer, it is due to the strain’s propensity to produce higher than normal levels of lactic acid.
The steps in the process outlined above are sequential. Many people have pitched Wyeast and White Labs cultures before shaking without serious negative effects; therefore, the I am assuming that one minute of vigorous shaking is not enough to stress the living daylights out of the initial mother cells. Those who want to avoid any possibility of encountering shear stress should wait until after shaking to inoculate the stater (i.e., pitch the Wyeast or White Labs culture). However, I will be curious to see if there are any major differences in performance. I believe that there is room for improvement with any process. However, we do rapidly reach a point of diminishing returns.
To be completely honest, I was amazed at how well the technique was received within the British home brewing community. For as stodgy as Americans believe that British people can be, the U.K. home brewing community appears to be far less dogmatic than the U.S. home brewing community. They have provided a lot of useful feedback. The technique has been a much harder sell within the American home brewing community because we have the propensity to make simple things difficult and oversimplify difficult things.
Amen, brother! Thanks for the info. Now that I know I didn’t make mine per your instructions, I’ll be curious to see how it performs. Maybe we’ll discover yet another way to do it.
Yes, I do believe that the cells may pick up more O2 during shaking, but there has to be cost. The $10,000 question is, how big is that cost? I do not have enough data points to draw a solid conclusion. What I do know at this point is that the method has been replicated by enough people to know that it is not a fluke.
I’ve been ruminating about this technique and here are my ruminations. Turning the wort into mostly foam isn’t necessary to achieve 99% of saturation based on what I have read elsewhere. Specifically, swirling a carboy for 40 seconds is enough to saturate wort with oxygen according to various reports and that produces very little foam. So what does turning the wort into foam do? I think if you don’t pitch yeast first then the answer is basically nothing; the wort is fully aerated but you could have gotten the same result without a workout.
So let’s assume that pitching the yeast into the starter wort and then shaking the starter is key. If nothing happens while the yeast is contained in the foam then all you got yourself is some shear-stressed yeast, wort at saturation and a sweaty brewer. So now you’ve wasted your energy and damaged your yeast.
So let’s assume that something happens while the yeast is suspended in the foam. Is it possible that the yeast can work fast enough to deplete the dissolved oxygen in the starter and that oxygen in the bubbles transfers into the wort and into the yeast before the foam entirely collapses but that this oxygen transfer is minimal without foam? In other words, shaken not stirred has the benefit of making a starter with pure oxygen, without the technology and cost?
What are your thoughts on why the vigorous shaking is key?
Remember what I mentioned earlier about the tendency of American home brewers to make easy things hard and oversimplify hard things? Here’s one of the areas where American home brewers attempt to oversimplify a hard thing.
There’s no way that 40 seconds of swirling fully saturates a 5-gallon carboy full of wort. Whoever made that claim was absent the day that they taught partial pressures in thermodynamics. There is not enough surface area, nor is there enough gas for saturation to occur in 40 seconds. There had to O2 pickup during the transfer. Once again, a gas dissolves into a liquid at the interface between the gas and the liquid. Surface area is critical to the process.
There is no magic bullet. The method merely takes advantage of physics to maximize dissolved O2 in a low tech way. While the cells that are on the surface of the thin layers of liquid that form the bubbles are subjected to 21% O2, does that O2 pickup impact growth? I do not have enough data points to draw a conclusion. Here’s what I do know, brewing yeast cells only need three things to grow: carbon (sugar is carbon bound to water; hence, the term carbohydrate), space, and enough O2 to support cellular health. They do not need to be stirred during propagation because most brewing strains exhibit NewFlo flocculation; hence, they will not clump (floc) or sediment until glucose, mannose, maltose, sucrose, and maltotriose have reached genetically set levels, which are on the other side of high krausen. Having fully air saturated wort from the start makes it easier for the mother cells to replenish their ergosterol and unsaturated fatty acid reserves early on (the same thing occurs when we diffuse pure O2 before pitching). A mother cell with full ergosterol and UFA reserves is a healthy cell. A mother cell shares her ergosterol and UFA reserves with all of her daughters. The fuller her reserves, the fuller her daughter cell’s reserves and her daughter’s daughter’s cells, and so forth. Ergosterol and UFAs make the cell plasma membrane more pliable, which makes it easier for nutrients to pass into and waste products to exit the cell. In effect, ergosterol and UFA levels affect a cell’s ability to utilize carbon for energy.
So could there be an advantage in this technique if you added pure O2 to the wort via a stone, or to the deadspace prior to shaking, or would that be unnecessary?
To me, and this is the reason I tried Mark’s procedure, it comes down to what’s the difference between the theoretical ideal and the practical reality? I’ve always said to Mark that while his methods were undoubtedly the best way to do it, I didn’t think that there would be any difference in real life. I decided it was time to find out for sure. I would say to all of you who are posting theories about why it will or won’t work, TRY IT for yourself and post your results. That’s the way citizen science works. We need more than just a few data points. And a big thanks to Mark (and Marshall and all the other experimenters) who make us all think and re-evaluate what we think we know.
One does not need to shake if one uses pure O2. Oxygen from air saturates at 8ppm at room temperature. Pure O2 saturates at 40ppm, which is almost double the amount of O2 that would be available to the cells if they were growing in air.
With that said, this technique is best suited to the propagation of class O1 (4ppm dissolved O2) and class O2 (8ppm dissolved O2) strains (from my experience, most of the strains available to home brewers fall into either class O1 or class O2 when it comes to O2 demand). I recently propagated a class O3 (40ppm)/class O4 (>40ppm) yeast strain (NCYC 1333), and its O2 demand pushed the outside of the envelope. What that said, the strain did achieve over 80% apparent attenuation with open fermentation, so I may be wrong.
so Mark- I have a stir plate with 5 speed settings. i stopped creating a vortex by lowering speed so that the wort was just circulating but no vortex. i leave it on for about 8-12hrs then shut it down and when high krausen, then if ready pitch or put in fridge until im ready.
without vortex, would this facilitate good culture growth without shear stress?
Shear stress is placed on the cells as long as there is turbulent flow. Lowering the stir speed just reduces the level of shear stress that cells constantly have to endure. Lowering the stir speed will lower the amount of O2 that gets dissolved before the culture starts to outgas (O2 does not enter the flask after the culture starts to outgas), which will result in poor health if one does not inject sterile air or O2.
I think this is something that has been imprinted on the minds of brewers (myself included): that yeast propagation occurs more readily or in a more beneficial way when the solution it is in is stirred - fast or slow. From what Mark is saying about how yeast is genetically modified to stay in suspension until the wort dips below a threshold level of sugar, this is not the case at all. If it were, we should really be setting up giant stir plates underneath our carboys during fermentation.
** Trying to use more accurate language - I don’t think yeast can ever truly be in solution.
The tendency to remain in suspension until genetically set levels of glucose, mannose, maltose, sucrose, and maltriose are reached is only exhibited by yeast strains that exhibit NewFlo flocculation. The are Flo1 brewing strains where flocculation is inhibited by mannose, but not glucose. NCYC 1269 is a Saccharomyces pastorianus (lager) strain that exhibits Flo1 flocculation.
NCYC 1269
Information
Flocculent.
Flo1 type flocculation.
For use in Tower Continuous Fermenters.
Depositor
Dr. R.N. Greenshields, University of Aston, Birmingham, UK.
Deposit Name
Saccharomyces cerevisiae, Saccharomyces carlsbergensis, Sacc
Month of deposit
March
Deposit Year
1968
Habitat
Lager production strain.
Hopefully, forum members noticed the comment about the NCYC 1269 being used in continuous tower fermentation. Continuous fermentation is a very different process from how we make beer. Tower fermenters are bioreactors that are used to ferment beer using a continuous process where beer is continuously drawn off of the top while fresh wort and O2 are added, and yeast is recycled. Fermentation occurs very quickly in a tower fermentation vessel. Ales usually ferment in around 4 hours whereas lagers ferment in around 10 hours. While exhibiting NewFlo flocculation, Whitbread “B” (a.k.a. NCYC 1026, Wyeast 1098, White Labs WLP007, and Fermentis S-04) was originally selected for use in tower fermentation vessels, which is why it is so darn flocculent.
NCYC 1026
Information
Flocculent.
NewFlo type flocculation.
1:5:4:5:5
O2, DMS 33 µg/l, low acetic, high lactic, diacetyl 0.42ppm only, used commercially in Tower
** Fermenters (continuous process),** non head-forming, no estery flavour. Contains 2µ plasmid.
Depositor
British Brewery
Deposit Name
Saccharomyces cerevisiae
Month of deposit
June
Deposit Year
1958
Habitat
Ale production strain
Understanding why something works or doesn’t work is science too and can allow knowledge to be applied to other ways of making starters. In particular, the biggest issue for me with this method is that I like having my starter finished before I brew; pitching at high krausen adds another complication to the brew day. The knowledge I gain here can help me make better starters the way I like to make them.
Having said that I may try this method the next time I do a split batch and post the results here.
I completely agree. And I really doubt this method is the be all, end all, ONLY good method. It’s likely just another very good method…but I won’t know without trying it and seeing for myself.
