Ancient ovens & baking

"The most important part of the baker's equipment is, and always has been, his oven. For six thousand years and more it is the oven, however crude or complex, which has transformed the sticky wet dough into bread. It is the oven which influences the final character of the loaf; the efficiency of an oven, or lack of it, can determine the success or failure of any bread baker's business. It is the heart of the baking process...It was the Egyptians who first used a manufactured portable oven. This was a beehive- or barrel-shaped container of baked clay, usually divided into two by a central horizontal partition. The lower section formed the fire-box in which were burned pieces of dried wood, often taken from the Nile, or even dried animal dung. The upper part, accessible from the top, was the baking chamber. An oven of similar shape, but often constructed of hollowed stone instead of clay, was used by the early Jews.

Instead of placing the dough pieces for baking on the bottom or sole of the baking chamber, the Jews put the pieces on the sides. Being damp and sticky they remained in place until they had dried out, when they fell to the bottom of the oven.

The Jews also had fixed ovens in some of their houses, frequently in the main rooms.

 These ovens or hearths took the form of clay-covered hollows in the floor which were heated with burning wood.

When the heat was sufficient the embers were raked out and the pieces of dough placed in the hollows and covered over.

 In Jerusalem there was a bakers' quarter where bread was baked in tiers of stone-built ovens, or furnaces as they were called in the Bible.

 In Ancient Rome bread ovens in the public bakeries were originally hewn from solid rock. These ovens were heated by the familiar method of burning wood in the baking chamber, raking out the ashes and putting in the dough to bake. The oven opening was closed with a large stone, sometimes sealed with clay. Ovens which worked on this principle, but were constructed of bricks or small stones, may still be seen in the ruined city of Pompeii. The fact ovens based on this simple design formed the majority of those in use throughout Europe until little more than two centuries ago. Although some of the early Roman ovens had chimneys to improve the draught and carry away steam, it was many centuries before chimneys were commonly used or dampers incorporated so that the heat could be more effectively controlled."
---The Story of Bread, Ronald Sheppard & Edward Newton [Charles T. Branford: Boston MA] 1957 (p. 107-109)

This type of oven may have been a small earthenware cylinder called tanner in the Bible as it is by present-day rural North Africans who still use it. A fire is kindled in the bottom and the dough is slapped against the hot interior walls, yielding curved disks of bread. Many other sorts of oven have been discovered in Israeli excavations.

 Larger, bi-level ovens have been unearthed which would have been more suitable for baking commercial quantities. They have a top rack to hold the loaves, while the fire below is stoked with "the grass of the field, which today is alive and tomorrow is thrown into the oven..." (Mt. 6:30). These baking techniques and others were known to the Romans, whose own commercial bakeries were not established until a relatively late date (171-168 B.C.). Once Roman administrative genius was applied to even so commonplace a task as bread making, the results would be impressive."
---The Bible Cookbook, Daniel S. Cutler [William Morrow: New York] 1985 (p. 371)

About ancient Roman ovens

"Many kitchens had an oven, furnace, sometimes called a fornax...The oven consisted of a square or dome-shaped hollow construction of brick or stone, with a flat floor, often made of granite, sometimes lava. It was filled with dry twigs when lit. When the fire was spent, the glowing embers were swept aside. The first heat of the glowing oven was suitable for baking unleavened or thin breads. Pizzas are still cooked this way, and this type of oven is still considered best for baking top-quality bread. Thin breads go in first, then large round loaves to in, or meat dishes, and the door is closed. After an hour or so, these are removed, but the oven is still hot, so finer pastries follow, then dishes that require the least heat, such as meringues."
---Around the Roman Table: Food and Feasting in Ancient Rome, Patrick Faas [Palgrave MacMillan:New York] 2003 (p. 132)

Compare with Colonial American ovens,

When did we start baking square-shaped bread in pans?

Food historian Elizabeth David sums this topic up most eloquently:
"Bread baked in pans or tins of uniform shape and capacity was a late development. Indeed, it seems to have been mainly a British one, Holland being the only other European country in which the method is in general use.

 In France only soft sandwich loaves and rusk bread are baked in tins, provided with a sliding cover so that almost crustless tops and perfectly even shapes are achieved.

Before the advent of mass-produced tinware English household bread was either baked in earthenware crocks glazed on the inside only, or the loaves were hand-molded and fed into the oven on wooden peels in the ancient manner, as was our bakery bread.

In the seventeenth century, deep tin or wooden hoops and, more rarely, round iron cake pans were used for yeast cakes, and there were earthenware dishes for pies, 'broad tins' for gingerbread, tin patty pans, plates and oven sheets for small cakes, biscuits and confectionery...and occasionally wooden dishes for molding rolls or small loaves--Robert May [English cookbook author: The Accomplist Cook, 1660] specifies these--but until the turn of the eighteenth century no mention is made in cookery books of tins for bread-baking. That they were in used long before that, probably in the early years of the century, seems certain.

 

Only the Dutch and the English took readily to bread baked in tins while the system was obviously rejected by the rest of Europe.

 Of course, at the time it must have seemed wonderfully convenient--it still does--to settle a batch of dough comfortably into space-saving tins, simply cover them with a cloth and transfer them into the heated oven when the dough had risen for the second time. This means much less handling in the shaping of the dough; the tricky notching, cutting or 'scotching', as the earlier writers called this part of dough management, could be dispensed with; and if the dough had been made up too slack no harm will be done; it would be confined within the walls of the tin and so could not spread and flatten out, but would spring upwards. By the early nineteenth century domestic cooking methods had already much changed. In the towns coal ranges with ovens were being installed in kitchens, so the separate bake house with its special bread oven was often abolished, and housewives or their cooks no doubt found that in the new ovens bread baked in tins or crocks was more satisfactory than the old hand-molded 'crusty' loaves, the all-round exposure to high heat in a small space without radiation from above causing a hard crust to develop before the inner part of the loaf had properly grown...In spite of the new tins and the new ovens, which certainly didn't become common until after the middle of the nineteenth century, most householders continued to make their bread as they had always done, often taking the prepared dough to a communal oven or to a local bakery to be baked.

 

About Yeast
"Yeast has been used in the preparation of food and drink for as long as there have been leavened bread and beer, but it was only in the 19th century, thanks to the work of Pasteur, that its nature was understood...Yeast is a single-celled fungus, of which hundreds of species have been identified. Those of the genera Saccharomyces and Candida are the most useful.

The single cells are very small: hundreds of millions to a teaspoonful. Instead of feeding by photosynthesis, as green plants do, they feed on carbohydrates...and excrete alcohol.

They breathe air and exhale carbon dioxide...Despite the simplicity of their structure, yeast cells can operate in alternative ways; one that suits bread-making and one that is right for brewers.

Given plenty of air and some food, yeast grows fast and produces a lot of carbon dioxide. It is the pressure of this gas which makes the bread rise. Only a little alcohol is formed.

 However, in a fermentation vat, where there is almost no air but an abundance of food in the form of sugar, the yeast cells change to a different mode, breathing little and concentrating on turning sugar into alcohol. The same species of yeast, Saccharomyces cerevisiae, constitutes both baker's and brewer's yeast...Beer leaven, known as barm, was used for bread-making until quite recent times. The making of beer, black bread, and the alcoholic drink kvass were traditionally linked in Russia...it is no longer true that the same yeast is used for brewing and baking...In addition of fermenting and flavoring other foods, yeasts themselves may also be used as food. They contain much protein and all but one of the B vitamins (B12)...They are consequently used to provide dietary supplements for countries whose diets are deficient in protein."
---Oxford Companion to Food, Alan Davidson [Oxford University Press:Oxford] 1999 (p. 855, 857)
[NOTE: according to this source, yeast is also used to make kefir, koumiss, soy sauce, sake, and the fermentation of cocoa to develop the flavor of chocolate.]