Chau, I'm sure you're aware of this, but keep in mind that Caputo makes low protein 00 flours, so unless these mobile guys tell you 'Caputo pizzeria
flour' (red or blue bag), then I still think the odds are high that they're not using pizzeria 00. Now... non pizzeria 00 60% dough being difficult to stretch- that's a little harder to explain, although, like you said, it might have been cold/cool. Even the slackest of doughs will tighten up when chilled.Density's Impact on Perceived Tenderness
Regarding the CY tartine HG bread having a similarly soft crumb to the CY 00 Mobile Oven crumb- it's important to be aware that air is a big player in tenderness perception. Just like air in ice cream gives it better scoopability, air in bread gives it a greater perceived tenderness. In order to judge the two doughs fairly, the crumbs really should be of equal density.CY impact/Yeast viability
Although dead yeast has been thoroughly proven to be a dough softener, I believe that the amount of dead yeast in your CY and the impact from that amount might be up for debate. It's one thing for commercial bakeries to purchase dead yeast (Glutathione) dough enhancers and add them to doughs for tenderizing effects/machinability, but jumping to the conclusion that previously frozen and/or stinky CY has enough dead yeast to create a substantial tenderizing impact is another story.
Even if you were working with CY with enough dead yeast to make a noticeable difference in tenderness, the glutathione would decrease oven spring.How Baking Works: Exploring the Fundamentals of Baking Science
"Glutathione is also found in whole wheat flour, in particular in the wheat germ. ... Toasted wheat germ will not have the same high glutathione activity as raw wheat germ, since glutathione is inactivated by heat. ... If glutathione is not first destroyed, bread dough softens and becomes slack, and oven spring decreases. The result is lower loaf volume and coarser texture."
Your previously frozen CY Tartine loaf had, from what I can tell, the same or better oven spring than your non CY tartine loaves. With the same oven spring, that should rule the tenderizing effects of glutathione out. The mobile pizza guys might, from the density of the end product, be getting tenderness from using consistently old CY, but I really wouldn't bet on it. As far as Lucci's using old CY- with their turnover, I think it's highly unlikely.
There's still unanswered questions here, such as why your old CY tartine loaf was so tender, but I honestly think the link between old CY and tenderness is a tenuous one.
Are you still in touch with the mobile guys? It would be nice to know if they freeze their CY.Rising Gluten
The bulk of my longer bakes are so long ago that I don't really recall the results. I know they were dense and without much character, but I can't really recall much about tenderness. I did have a slightly more recent experience baking pizza at a friends house, in their oven, with their stone, a few years back, that I can remember much more distinctly. This was around the time when I was still doing very late re-balls. I don't recall the exact formula I was using, but I'm pretty sure it was 100% All Trumps, and, when I made it at home, it was pretty chewy with a 4 minute bake (especially so with the late re-balling). Because my friend had an anemic oven and stone, the bake time was extended to 8 minutes. Result? Dense, but surprisingly tender- almost cake like.
I've been tossing a theory around my head that, although gluten is formed just by the hydration of the flour in cold fermenting dough, it's also formed by the action of the rising/expanding dough. If this is the case for fermentation (and I'm relatively sure it is), then it stands to reason that as dough begins to bake, that same rising action might activate gluten as well. This could explain why a dough of the same hydration would be tough when baked for 4 minutes, but tender when baked for 8- because the lack of oven spring didn't activate much gluten.
This theory would work, IF, it weren't for the tenderness of Neapolitan crumb- especially with the noticeable tenderness increase going from more than 2 minutes to less than 90 seconds.
Caputo going from 90 second to 2 minute - less oven spring, decreased tenderness
All Trumps going from 4 minutes to 8 minutes - less oven spring, increased tenderness
Now, I only have one test here for the All Trumps, so I really can't say that longer HG bakes produce more tender crumbs, but the test I did do was intriguing and could somehow relate to this current conversation.
One thing I'm taking from this is that I might need to fail more- that even though I wouldn't want to eat the 8 minute 'mistake,' there may be more lessons to be learned from long-ish bakes. Maybe.