The first Biblical reference to a woman doing specific work (other than childbirth) refers to a task done four thousand years ago. Abraham entertained unexpected guests, and Sarah made cakes for them.
So Abraham hurried into the tent to Sarah and said, “Quickly, make ready three measures of fine meal, knead it and make cakes.”
Women made cakes from meal, or fine meal (flour), and “roasted the dough in the ashes” or “under the coals” or on hot stones. The ancient people used four kinds of grain to make meal: millet, oats, barley and wheat. Sarah could have made cakes from any of the grains, although barley and wheat were preferred. Barley meal made healthful roasted flatbread and became a symbol of Israel’s strength.
“Nowhere—not even in Homer—is there written so forcible a tribute to barley as in the Book of Judges, where an Israelite dreams of a cake of barley bread tumbling into the Midianites’ camp and destroying all of Israel’s enemies.”
While barley, millet and oats make satisfying flatbreads, these grains have little or no gluten, which is necessary for making raised bread. Millet is gluten-free; oats contain a little gluten; and barley has less gluten than wheat. Because of its high gluten content, wheat flour makes exceptional raised bread. Kneading dough made from wheat flour develops strands of gluten. Gluten is stretchy and traps the gas generated during leavening. It enables bread to rise and hold its structure. Raised bread can be made with other grains if they are combined with wheat flour or another gluten source. Because of wheat’s baking qualities, it “became the king of grains—and remains so to this day.”
Did Sarah know how to make raised bread from air-borne yeast? She might have. Historians believe that Egyptians “invented” raised bread about 500 years before the time of Abraham.
“Around 2,500 B.C. the Egyptians learned how to exploit the gluten in wheat flour making the first raised breads from yeast. This discovery alone pushed wheat to the forefront ahead of the other prized grains of the day, oats, millet, rice and barley. The Egyptians grew huge amounts of wheat. They eventually started exporting wheat to other parts of the new world.”
The Egyptians “made an enormous contribution to civilization” by setting aside their dough until it fermented, and “were known as the bread eaters…[because it was] the principal good of all Egyptians.”
How the Egyptians first discovered the activity of invisible air-borne yeast is not known. Was an Egyptian woman called away from mixing her dough long enough that yeasts began to ferment it? When she returned and found a slightly bubbly mess, did she throw up her hands and say, “I’ll have to bake it anyway.” It’s lost to us.
It is likely that the Israelites learned to make raised bread while they were slaves in Egypt. At the time of Moses, Egyptians already had brick ovens and were capable of making raised breads in various shapes, a skill attested to by Egyptian tomb paintings. Earlier Hebrews, nomadic peoples like Abraham who lived in tents and followed their herds, “could not be bothered transporting such ovens through the land…either they parched the grain, like the reapers in the Book of Ruth, or they set flat cakes to bake” on a hearth or under coals.
Adam Clarke states that Sarah made cakes on a hearth as was common among the Bedouin tribes. “When the hearth is strongly heated by the fired kindled on it, they remove the coals, sweep off the ashes, lay on the bread, and then cover it with hot cinders.” Commentators John Gill and Jamieson, Fausset and Brown agree with Clarke that Sarah made cakes from sifted meal and cooked them on a hot surface under embers.
Time to Rise
It is stated on some Jewish websites that flour made from any of five basic grains (wheat, oats, rye, barley and spelt) and mixed with water begins to be leavened by natural yeasts in 18 minutes. Orthodox Jews, who seek to avoid any chance of dough beginning to ferment, bake their Passover matzohs quickly. Wild yeast will begin fermenting sugar when it settles on hydrated flour. But it takes more than 18 minutes of yeast activity to achieve dough sufficiently strong for baking a sizable raised loaf.
Peter Reinhart in The Baker’s Apprentice describes preparing an initial “seed culture” of wild yeast, flour and water over a period of one to four days. A small portion of this starter culture is mixed into a measure of flour and water to make a loaf of sourdough bread. After the dough is kneaded to develop gluten, it rests two to four hours as the yeast works. After resting, the dough is shaped and rises a final time before being baked.
No Time to Rise
Ancient Israel had to leave Egypt quickly. After God administered the tenth plague, He wanted Israel out in a hurry. They couldn’t wait the hours to leaven, knead, shape, rise and bake their dough in Egyptian ovens. As stated in Exodus 12:33-34, the Israelites left with unused kneading bowls on their shoulders. Their daily bread was leavened but they didn’t have time to prepare it.
And the Egyptians urged the people, that they might send them out of the land in haste. For they said, “We shall all be dead.” So the people took their dough before it was leavened, having their kneading bowls bound up in their clothes on their shoulders.”
A remarkable sign
Israel learned to make leavened bread in Egypt. Women baked it every day. It was a staple of their diet.
It was a remarkable sign for the Israelites to leave the land of “bread eaters,” the people who “invented” raised bread, who built brick ovens, who made fanciful shaped loaves, who baked bread for their gods and ancestors—to depart without any of the bread of Egypt.—Mary Hendren
 Six Thousand Years of Bread, H.E. Jacob, p.35.
 Same source, p. 15.
 Same source, p. 15.
 http://www.aaoobfoods.com, “Grain Information”
 Six Thousand Years of Bread History, pp. 26, 31
 Ibid, p. 35
 Adam Clarke’s Commentary, note on Gen.18:6, p. 42
 The Bread Baker’s Apprentice, Peter Reinhart, pp. 227-235