So, the baguette. Just a skinny stick of bread, right? Just more of the same stuff that comes in a loaf, only rolled out into a long skinny shape. What’s the big deal?
In fact once upon a time it was a very big deal, primarily because the baguette was the edible outcome of series of very important technological leaps, kinda like a sous vide fish fillet is today. Peasants living in the French countryside couldn’t have made one if they’d tried. Nor could the urban bakers of Paris prior to the mid-1800’s, despite the claims of some food historians that Parisian bakers had already developed the “proto” baguette before Viennese long bread got there. They couldn’t have, for the simple reason that they didn’t have the technology.
A huge part of that technology was of course the gas-heated, steam-injected deck oven that I mentioned, a rather obvious technical contribution made (of course) by the Viennese. Another critical part, again rather obvious, was the flour. Steel rolling mills capable of producing flour of a sufficient fineness that it could be expanded into a tender white fluff were themselves a product of the Industrial Revolution. Country folk made do with flour that was milled roughly by stones, which released far less of the wheat’s glutenous potential.
Another critical innovation, which is far less obvious, is yeast. Peasant bakers, being poor and relatively unskilled, baked all of their bread using naturally-occurring yeasts or levains. Nothing wrong with those. They were easy and available, and made very flavorful bread. The down side is that the way they were traditionally employed (i.e. in a days-long “building” process) meant they worked only very slowly, yielding a very dense loaf.
A baguette demands quite a bit more leavening firepower, which was delivered by way of so-called “brewer’s yeast”, the microbe-rich scum leftover from the beer making process. This many urban bakers used to “spike” their bread doughs to create a lightning-fast rise and a light-as-air crumb. Of course you needed to be near a brewery to have consistent access to brewer’s yeast (which eventually became packaged yeast), but even more than that you have to have the know-how, which French bakers in general lacked (that is, until they were shown by the Viennese).
What did it all add up to? A very toothsome and appealing foodstuff that could be produced in the (relative) blink of an eye, multiple times a day if need be. The perfect bread, in other words, for a busy urban environment full of hungry paying customers.