Yeast slurry

[McMullan]

If you perform a Google search on the terms "magnetic stirrer" and "shear stress," you will get many hits related to patents that attempt to overcome the phenomenon in stirred cultures as well as publications about the phenomenon, including rotational speeds that limit shear stress. I am not pulling this information out of thin air. I started to study this phenomenon after switching to a magnetic stirrer from hand shaken starters.

A quick google search hasn't revealed anything for the home brewer to worry about. Do you use a stirrer or have you stopped using one?

 

[saccharomyces]

I own a Hanna HI190M stir plate. However, I stopped using it, and went back to using my method last year. I recently purchased an orbital shaker, so that I could run a few experiments. Eventually, I want compare starters made with my method to magnetically stirred, orbitally shaken, diffused air, and diffused pure O2 starters. I need to acquire more lab equipment before I can perform unbiased experiments.

 

[F00b4r]

I saw this interesting post on yeast vitality today, any thoughts gentlemen?:

http://brulosophy.com/2015/06/29/ye...e-cell-count-vs-vitality-exbeeriment-results/

 

[McMullan]

I own a Hanna HI190M stir plate. However, I stopped using it, and went back to using my method last year. I recently purchased an orbital shaker, so that I could run a few experiments. Eventually, I want compare starters made with my method to magnetically stirred, orbitally shaken, diffused air, and diffused pure O2 starters. I need to acquire more lab equipment before I can perform unbiased experiments.

I respect independent science and wish you well with it.

 

[McMullan]

I saw this interesting post on yeast vitality today, any thoughts gentlemen?:

http://brulosophy.com/2015/06/29/ye...e-cell-count-vs-vitality-exbeeriment-results/

Yes, an interesting experiment. Not very scientific, but interesting. Using healthy yeast is the key to successful fermentations. The healthier they are, the less you need, probably. I used to pitch liquid yeast without making starters. They'd usually be fine, but occasionally I'd get a slow fermentation, a stuck fermentation or fall short of the predicted attenuation. After a long brew day, these problems would be ****. Ever since making starters, I haven't had any of these problems.

 

[F00b4r]

Yeah despite the people behind the site always cautioning on the validity of their experiments I often see them being quoted as gospel on forums, I thought it was interesting that the yeast health over pitching rate seemed to have come from a commercial brewery.

 

[MyQul]

@saccharomyces You've talked about pitching rates to either produce a clean beer or one with more esters. Wouldn't it be better to control that using temperature and thus avoiding the consequences of under/over pitching?