Thanks dharalson, I'm very familiar with that article, and I have several problems with it. Looking at fig. 1 from the article "effect of aeration on yeast cell number", it says that 500 ml of BrewTek Superwort was pitched with a saturated 10 ml superstarter culture of BrewTek yeast. Okay, that doesn't tell me much; what was the inoculation rate of the starters? The other thing that bothers me is that the control starter for the "experiment" was done with an airlock as opposed to tinfoil, by a different person with a different strain of yeast made by a different manufacturer, under who knows what conditions. How does that qualify as a controlled experiment? It doesn't.
I have taken 2 liters of wort and split it into two 1 liter flasks. One flask had no aeration whatsoever, the other flask was put on a stir plate. Each flask received 1 White Labs vial of 1056 yeast (with the same expiration date), giving them an inoculation rate of about 100 million cells/ml. Both were left to ferment for 24 hours, then cold crashed for 24 hours. Since I don't have a hemacytometer, I figured the thickness of the yeast cake would be a pretty good indicator of growth, if there was indeed a 10 fold increase in yeast cell count the slurry in the aerated starter would be significantly thicker, but at the end of the experiment both flasks had approximately the same amount of slurry. My conclusion was that a given volume of wort has a saturation point for yeast cells, and this will be dependent upon the inoculation rate. Chris White has stated that this saturation point is about 200 million cells/ml, which means if you pitch 100 billion cells into 1000 ml of wort it will never grow to much more than about 200 billion cells, no matter how much oxygen you give it, the yeast will simply run out of food. This seems to correlate with my experiment, and the calculations from YeastCalc. I hope to someday obtain a hemacytometer, and microscope. I would like to do more experimenting with different inoculation rates, so as to really nail down a good formula for calculating stir plate growth. Until then this is what I'm going with.
Cheers.