I was told by a friend that, when making pizza dough, I should add the salt at a later stage than the yeast, because it might disturbe the yeast from doing its thing...
I apologize for not having anymore concrete information, I just wanted to check this...
Salt in high concentrations can kill yeast yes. So can sugar, though salt is so much better at it. You see both are hygroscopic, meaning that they suck water out of stuff. This induces osmotic stress to the yeast cells leading eventually to cell breakdown (aka death).
On lower concentrations salt will throttle the yeast fermentation producing a richer and more uniform crumb.
Adding the salt early or later in the process will have a big effect on your dough, but that won't be because of the way it messes up with the yeast. Salt is supposed to coagulate gluten proteins, in a sense it "stiffens" the dough. On various situations this should happen late in the process (e.g. see the "Delayed salt method" used for sourdoughs).
For pizza dough I'd add the salt early.
Salt doesn't kill yeast entirely, unless there is too much of it, but it does slow down its growth rate. So adding the salt later would allow the dough to rise more.
In the case of pizza dough it probably doesn't matter all that much, and if you find that it doesn't rise enough, you can also leave more time for it to rise.
Given the amount of salt used in bread, the answer is no according to The Bread Bakers Guild of America:
Most scientists believe that at 2% of the flour weight or less, salt alone does not significantly alter either the yeast’s gassing power or the bacteria’s acid production. A study measuring the gas production in a fermenting dough has shown that gas production is retarded by only about 9% in a dough containing 1.5% salt (based on the flour weight).
https://www.cargill.com/salt-in-perspective/salt-in-bread-dough
Greg Blonder, a Professor of Design and Product Engineering at Boston University, carried out experiments to see how salt affect yeast, with some nice pictures to show the results:
https://genuineideas.com/ArticlesIndex/saltyeast.html
Summary of the experiments: 1) salt at 3% by weight does not kill yeast and does not change the effectiveness of co2 production by the yeast. 2) Salt does strength the gluten so the dough will rise less (which is probably why many believe that salt retards yeast). 3) Dissolving salt in water prior to mixing helps strength the gluten more than a later dry mix (again, probably why some people though that early mixing damaged/killed/retarded the yeast)
I assume the experiments were carried out using commercial dry yeast, so the result may or may not apply to wild yeast in sourdough starters.
9:15 am: I thought I would add my yeast to the liquid prior to mixing in the flour, etc. I added the olive oil, agave, and 2 t.SALT to the 3 cups warm water not knowing that the salt might prove to kill the yeast. I had a feeling though, so I checked. Sure enough I obviously goofed big time. Well my dough is hopefully rising now, so we'll see. 9:32 am ... well, it's rising, but maybe a little slower than usual. Hopefully another 15 minutes or so will tell the tale. 9:50 am: It has doubled and is now baking and looks beautiful! Guess I lucked out! Maybe the ratio of salt to water was mild enough so as not to kill the yeast.
