Techbrau, I am going to say this because it needs to be said. If you are holding up Kai's work as the gold standard, then you are not the hotshot scientist that you claim to be. Kai's work is so full of holes that I can shoot it down. First off, I am not trusting data from anyone who a) does not know the proper piece of lab glassware to use when preparing slants, and b) does not know that one does not prepare plates by placing filled Petri dishes in an autoclave. If one cannot perform two of the most basic tasks in microbiology correctly, how is anyone supposed to trust that he/she took and diluted his samples for counting correctly?
Have you ever heard of Jean De Clerck? De Clerck’s work has stood for over fifty years. De Clerck stated that one gram of extract contained enough carbon to produce one billion cells. Other scientists have be able to push the figure up slightly, but no one, and that list includes hardcore professional brewing scientists, has been able to produce 2.5 billion cells per gram of extract.
The claim that Kai made about stirring keeping the yeast strain working longer demonstrates complete lack of understanding of how flocculation works. Brewing strains do not need to be agitated to remain in suspension. If brewing strains needed to be agitated to remain in suspension, they would be of no use to brewers. What keeps brewing strains in suspension is that they exhibit NewFlo flocculation, which means that they will not begin to flocculate until glucose, mannose, sucrose, and maltose reach genetically set levels. Spinning a culture is not going to lower these thresholds.
The reason why Kai achieved a lower cell count with his non-stirred starters is because he did not provide adequate aeration. If he had adequately aerated his non-stirred starters, he would have seen equal or better results. Spinning does change the fact that yeast cells in a medium that is above the Crabtree threshold derive 2 ATP molecules from a molecule of glucose while metabolizing glucose via the fermentative metabolic pathway. Hence, Kai's claim that one can expect at most 0.4 billion cells per gram for a non-agitateds starter is little more than meaningless data from a guy who meant well, but got so rapped up in himself that he did not perform the reality check that all scientists and engineers perform before publishing what could be ground breaking data. That reality check is to have other scientists (or engineers in the case of an engineering problem) repeat the experiment to see if they receive the same results. If the results hold, then the data is valid; otherwise, it is junk science.
You can say what you want about the method that I presented on this forum, but it requires a total outlay of a couple of dollars instead of one hundred dollars plus. Well over 100 hundred people have been able to repeat my results of being able to pitch yeast grown in 50% of the starter wort that they used with a stir plate with equal or better results (and that is the number of people that I know have attempted the method). I have had many people tell me that fermentations pitched with a Shaken, not stirred starter blew the lids of their fermentation buckets. That never happened to them when they used a stir plate.
Finally, all of this talk about diffusion motivated me to look for a definitive answer as to whether O
2 diffuses into a flask that contains an active fermentation. I was unsuccessful in locating any supporting information; however, I did find an example in a book that correlates with my explanation as as to why the Shaken, not stirred method works well. If one visits the link shown below and scrolls down to Example 18-1.1 Aeration of a fermentation broth, one will discover that my assertion that increasing the surface area per unit volume trumps increasing the mass transfer coefficient (i.e. increasing laminar or turbulent flow) is correct. Gas-liquid foam, with its high specific surface area, is one of the reasons, if not the sole reason why the Shaken, not stirred works as well as it does for being such a trivial technique. My other hunch has to do with the fact that yeast is basically pitched into wort that is saturated immediately after pitching (or immediately before pitching). Jim's use of direct O
2 injection supports this hunch. I have always said that my method is just a low-tech, low-cost substitute for an O
2 bottle and a diffusion stone, nothing less, nothing more.
https://books.google.com/books?id=dq6LdJyN8ScC&pg=PA513&lpg=PA513&dq=Gas+diffusion+across+different+pressures&source=bl&ots=vKUx5Cngnm&sig=60l3GRMJLKC9mixHloplXHIgrRQ&hl=en&sa=X&ved=0CE4Q6AEwB2oVChMIidDjq6LbyAIVQ1Y-Ch3iggtN#v=onepage&q=Gas%20diffusion%20across%20different%20pressures&f=false
Topic: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results! (Read 16484 times)
