Primary fermentation Pressures

[fumbles]

What is the reason for adding addition pressure, apart from a CO2 blanket that could be at atmospheric pressure. How does pressure change the fermentation of yeast? Does a higher pressure force more anaerobic activity from the yeast? More off-flavors from esters? I've heard at high pressures CO2 is forced through the yeast cell membrane, which kills it. It would seem that an optimal pressure would exist for a chosen style and profile. Does it slow down fermentation times? Yeast companies give an optimal temperature range, why not an optimal pressure?
This is what I've found so far...
https://www.homebrewtalk.com/f35/does-pressure-stop-fermentation-162761/

www.terifahrendorf.com/Closed-Pressurized-Fermenatation.pdf

This article is 51 pages, and it is difficult to check facts/opinions. I wanted to have a more uniform and concise explanation.
https://www.homebrewtalk.com/f13/closed-system-pressurized-fermentation-technique-44344/

 

[KevinM]

http://www.probrewer.com/resources/library/bp-healthyyeast.php (better yet) www.whitelabs.com/beer/Yeast_Storage_&_Maintenance_Article.pdf
Carbon dioxide can build up quickly in yeast slurry, and if kept under pressure will cross the cell walls and kill yeast cells. Pressures over 35 psi can be toxic to yeast, and soda kegs are rated over 100 psi. So if you use these kegs, shake and vent pressure regularly, at least once per day.
Some science article I couldn't access: http://www.ajevonline.org/cgi/content/abstract/31/1/46

-regarding pressure exerted on yeast in a conical fermenter: http://www.danstaryeast.com/library/conical-fermentation-effect-yeast
"(2) CO2 should present no problem in the fermenter size that the average home brewer would use:

CO2 @ 0.2 atmospheres pressure stimulates yeast growth.
CO2 @ 0.5 atmospheres pressure begins to exert a negative effect on yeast growth.
CO2 @ 3.0 atmospheres pressure stops growth
CO2 @ 3.0 atmospheres pressure does not stop fermentation-alcohol production.
10 ft. height fermenter = 0.3 atmospheres.
"
Sankey/Corny kegs are a quarter or so the height, and has less volume so less pressure involved from it.
1 atmosphere is about 14 psi.
More stuff that involves pressure, kind of http://www.danstaryeast.com/library/yeast-growth.

Still, no scientific papers were able to be found, but if a yeast producer has this part, it ought to be somewhat useful. Google is my friend.
(I thought my 50 psi was too high, oops, guess I'll get that right spunding valve that I said I needed.)

 

[fumbles]

This has a lot of interesting stuff

http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1992.tb01137.x/pdf

THE FORMATION OF ESTERS AND HIGHER ALCOHOLS DURING BREWERY
FERMENTATION; THE EFFECT OF CARBON DIOXIDE PRESSURE
Bv R. S. Renger, S. H. van Hateren and K. Ch. A. M. Luyben

From what I understand from the paper; esters and fusels are a function of co2 pressure... How much ester and fusel concentration is from elevated temperatures and how much is from the reduction of co2 in solution?