grathan said:
It is commonly said that dry yeast doesn't require oxygenation.
It's in textbooks used by most of the brewing schools. But, I must let you know that it's in a chapter devoted to yeast health that says that's about the worst way to manage yeast.
I don't know the reasoning here, but let's assume the science is correct. By the same theory if you pitch liquid yeast that is also of a large quantity and heavily oxygenated, that that has to be a similar concept.
IF that were ACTUALLY science.... But, it's a very recent development where a major, respected and reliable packaged yeast company started drying their yeast with an oxidizer. Empirical evidence showed that this yeast started faster when pitched directly into wort than if it were rehydrated in water.
From my experiences my beers have improved since I have stopped blasting them with pure O2. I use a 2L stirred starter on 1.050 batch ( I couldn't tell if this is overpitched by experts' standards, but I am guessing that it may be )
My thoughts are that if your yeast pitch is oxygenated and is of large enough quantity, there will be very little growth and therefore very little oxygen consumption. And possibly this leftover o2 will end up hurting your batch. I know this is wild speculation and I unfortunately I don't have a dissolved o2 meter to prove it wrong...
This is sound judgement. Yes, unused O2 can become a staling issue later. Yes, going in with 100% or more of the viable yeast needed for the gravity and volume eliminates growth.
But, let's discuss the implications of this. If your yeast needs no growth, then it needs no nutrient, amino acids, proteins or to reduce it's own byproducts, either. But, it will use those things quickly. and in a constant need for nutrients will turn to autolysis to find it.
It will multiply by at least one generation, which doubles your pitching rate. The yeast now has more volume, which takes up beer. Plus, higher yeast populations often have a harder time flocculating.
The yeast calculators tend to get you to where one to three doublings of yeast populations occur. This is the most complete use of nutrients possible. It builds healthier cell walls and increases the yeast's ability to flocculate as key wort components are used up.
Grathan, if what you're doing has improved the quality of your beer, keep doing it! You're procedure is fine, but the logic behind it is the smashing together of two different procedures and goals.