Miguel writes, "I tried to replicate an ancient Egyptian bread, starting with the right kind of wheat, the grinding and the baking… I also made a modernized version inspired by Egypt."
The science behind yeast, which transforms sugars and uses bread gluten to make holes and to make it softer wasn't fully understood until thousands of years later. Nevertheless, its ability to make bread rise was probably known. It is difficult to say if Egyptians used yeast to leaven the breads. But there's a couple of reasons that can lead us to believe they did:
* The cultivation of wild yeast present in the air and in the water is one of the oldest bread making traditions. Flour and water that has been left outside after a while tends to grow some variety of wild yeast. Not only does this improve the texture, but also the flavor. Pieces of that bread can be used later on to make more bread, or like the Sumerians did, to make beer. This actually became a way of cultivating and domesticating the best strains of yeast. Yeast strains present in the Nile are still used today for bread and beer-making.
* The two staples of the Egyptian diet, often produced side by side, were bread and beer. Even if they didn't use beer to make bread (something that is easy to assume they did), the yeast present on the air and on the grain probably was present on the bread that was left out in the air.
* Archeological evidence shows that beer was made by first baking "beer bread," a type of well-leavened, lightly baked bread that did not kill the yeasts, which was then crumbled over a sieve, washed with water in a vat and then left to ferment. Moreover, a strain of yeast, Saccharomyces cerevisiae present in the region of the Nile, was found to be used in bread and beer making.