Does anybody know the actual process/ingredient they use to aereate the dough during baking?
My guess is that extra leavening (maybe baking powder) is added during the final kneading. That would account for those characteristic air bubbles, wouldn't it?
As a young man my father was friends with two guys whose father was a baker (and who succeeded him in the small neighborhood business). When returning from Suturday nights on the town, the three would go to the bakery on the way home and help prepare the loaves for the oven.
He (my dad) said that there was a "trick of the trade" to the lightness of the local bread. I forgot to wheedle it out of him back then. Who knew that all the neighborhood bakeries would disappear? Or that home breadmaking would ever come into vogue?
The only place I've ever encountered bread with a similar (in fact, identical) appearance, taste, and texture was in Tampico, Mexico, which I only visited once more than 30 years ago. I imagine there's more Mexican influence---brought in through coastal trade--than is generally thought. Chaurice, for example, as a local variant of chorizo.