CULINARY INFO
Bread

The staff of life. In its most basic and simplest form, it is simply a baked food made from a ground or milled cereal grain, usually wheat flour and water. From this basic mixture, it can be leavened (aerated) by chemical or microbiological action. Because of the leavening process, the making of even the simplest kind of bread is a fairly complicated procedure. Only wheat flour contains gluten, a substance that supplies the structure needed for leavening. Many non-wheat-growing cultures have never known bread.

Bread making may have originated in Egypt. Archaeologists have found pieces of bread that show clear evidence of leavening action in deposits dating from about 3500 BC. The "sun bread" of Upper Egypt, made today by a method that must be very old, is prepared from a thick batter that is placed in the sun to leaven and partially dry before it is baked into a hard-crusted loaf with a sweet, soft interior. By the dynastic period, loaves of special shapes and sizes were made for religious purposes and for consumption by different social groups.

Bread was a common foodstuff in Rome, and a sophisticated baking industry developed, using mechanical kneading devices. During the early Middle Ages, baking technology regressed; although eventually the growth of bakers' guilds resulted in improvements in techniques and tools. During the Industrial Revolution, an acceleration occurred in the development of baking technology, and today the making of bread is a highly mechanised process in most Western countries.

Contemporary accounts of the 15th century wedding feast of King Matthias of Hungary list sauces thickened with bread, viz. old loaves are soaked in water (or milk?), forced through a strainer and the resulting puree added to the soup, stew or sauce as a thickener. Smaller loaves may have been favoured because of the higher ratio of crust to bread, described in detail in The Cuisine of Hungary by George Lang.

Hungarian cooking of the period took strong direction from the new Queen, who was Italian and brought her own kitchen staff to Budapest. This MAY be a northern Italian technique. If so, it should be documented, because (if memory serves) the first Italian cookbook to be printed was both from the new Queen's (Beatrice?) city and predated the marriage. Also, since much of French cooking has the same roots, there may be a Italian link to frying flour to make "crust".... our modern roux in France and Rantas (pronounced "rahn-tash") in Hungarian.

Another insight: 19th Century Hungarian cooking often put such a stale roll or slice of bread into a soup dish before the soup is poured. Romans about the time of Christ served a bean dish much the same way...cannellini type beans in thin broth served over stale bread which had been rubbed with garlic and salt.

Also, Polish Heritage Cookery describes preparing various dishes "a la Polonaise" and comments on their relative antiquity. A "Polonaise" finish is a sauce or drizzle of butter in which bread crumbs have been browned. Especially good on cauliflower. This may have indirect Italian roots, but I can't be sure because I have not dated really early use of bread crumbs and butter in this way.

BREAD MOULD
Perhaps the most widely studied mould is the familiar bread mould, Rhizopus nigricans, which appears on bread that has been moistened, exposed to air, and placed in a warm, dark place. Bread moulds have different types of hyphae. Those that spread along the surface are called stolons. At intervals along the stolons, clusters of shorter hyphae, called rhizoids, extend down into the food supply and secrete enzymes that break down sugar and starch into digestible food. The rhizoids absorb the food, and water as well.

Moulds can reproduce both asexually and sexually. To produce asexually, some moulds develop special reproductive hyphae (sporangiophores), which extend into the air. Black knobs, or spore cases (sporangia), appear at the ends of these hyphae after a few days. When mature, the sporangia break open and release their spores, which will germinate if they reach a suitable environment. Sexual reproduction is accomplished through a form of conjugation. Two different mating types of hyphae, termed plus and minus, form short, specialised side branches. If the tip of a plus branch meets the tip of a minus branch, conjugation occurs. Each tip becomes a gamete cell, with two fusing to form a zygote. The zygote matures into a zygospore, which may germinate after one to several months if conditions are favourable



The loaf shape

To Americans "loaf shaped" connotes something rectangular with definite square corners. That would not occur to people in most of Europe, where nearly all breads are baked 'free standing'; the long French and Italian loaves, the round rustic breads found from Russia to Spain, fancy braided harvest loaves and so on. Only in the Netherlands and English speaking world is bread usually baked in rectangular loaf pans.

England and Holland only changed to the loaf tins because it was more convenient for bakers, and to get a higher loaf ; the dough cannot spread sideways as it bakes, and therefore the loaf tin bread raises higher. This was partly because of the cult of the soft, inner crumb of bread during the 17th and 18th century.

It is also true that in the loaf tin bread world, bread tends to be sliced and eaten by itself, either buttered or made into sandwiches. While the rest of the world with free standing breads, eat the bread in chunks with a meal, so the shape of the bread is irrelevant. When the French make sandwiches they use a bread called, ‘pain de mie', which is baked in a long loaf tin with a lid on it to stop the dough from raising too much so as to obtain a very dense crumb.

Loaf tin are quite ancient, the ancient Egyptians had scores of different shapes; square conical and yes even pyramid shaped ones. They probably used them for baking barley bread, since barley dough does not rise at all you might as well give it a cute shape.

TYPES OF BREAD
Whole Wheat Bread
Whole wheat bread is made from a meal that contains essentially all of the components of the cleaned wheat kernel in the same proportions as they are found in the grain. The loaves are dense, firm, dark in colour, coarse in texture, and strong in flavour. Wheat and part-whole-wheat breads contain a mixture of whole grain meal and enough white flour to assure good dough expansion and a lighter colour and density.

Pumpernickel and Rye Bread
Pumpernickel, a dark, tough, and close-textured loaf, is made from crushed or ground whole rye kernels, without the admixture of wheat flour. Rye and wheat flours are added to produce rye bread, which has a better texture, lighter colour, and milder flavour than pumpernickel. Caramel coloring and caraway seeds are often added to rye bread. Rye bread can be made by the sourdough method, where leavening and flavour result from the addition of a small amount of old dough in which lactic-acid-producing bacteria have developed. These micro-organisms ferment some of the carbohydrates in the fresh dough batch, producing characteristic sour tastes and odours.

Salt-Rising Bread
Salt-rising bread is made with a sourdough high in salt. The salt limits the growth of common bakers' yeast while creating a more favourable environment for growth of bacteria that influence the flavour.



LEAVENING
Dough was originally leavened by adding sourdough left over from a previous day's bread production. The relative acidity, alcohol content, and low oxygen tension in the interior of a sourdough mass tend to inhibit the growth of moulds and undesirable bacteria while allowing preferred strains of YEAST to proliferate. The results are unpredictable, however, because varying amounts and types of yeast can develop in the sourdough’s. An improved method of ancient origin uses the relatively pure yeast that settles out from beer or wine.

Yeast
Today bread is leavened with yeast manufactured by inoculating pure cultures of the selected strain of micro-organism into carefully formulated and sterilised liquid media. The yeast cells multiply under controlled conditions; they are harvested by centrifugation and filtering, washed free of media, and packaged for delivery. Bakers' yeast is composed of the living cells of Saccharomyces cerevisiae, a unicellular micro-organism. Yeast performs its leavening function by fermenting carbohydrates such as glucose, fructose, maltose, and sucrose. (It cannot metabolise lactose, the predominant carbohydrate in milk.) The principal products of fermentation are carbon dioxide, which produces the leavening effect, and ethanol. Yeast also produces many other chemical substances that flavour the baked product and change the dough's physical properties.

Although most breads and rolls are leavened by yeast, some bread-like products (Irish soda bread, corn bread, certain kinds of muffins) are leavened by chemical systems such as BAKING POWDER.



THE SCIENCE BEHIND BREAD MAKING
Bread is the product of baking a mixture of flour, water, salt, yeast and other ingredients. The basic process involves mixing of ingredients until the flour is converted into a stiff paste or dough, followed by baking the dough into a loaf.

The aim of the bread making processes used in New Zealand (mechanical dough development, bulk fermentation and no-time doughs) are to produce dough that will rise easily and have properties required to make good bread for the consumer.

This information sheet gives an overview of the general process, and science behind bread making. It does not consider the differences between baking methods.

Breadmaking involves the following basic steps:
To make good bread, dough made by any process must be extensible enough for it to relax and to expand while it is rising. A good dough is extensible if it will stretch out when pulled. It also must be elastic, that is, have the strength to hold the gases produced while rising, and stable enough to hold its shape and cell structure.

Two proteins present in flour (gliadin and glutenin) form gluten when mixed with water. It is gluten that gives dough these special properties. Gluten is essential for bread making and influences the mixing, kneading and baking properties of dough. When you first start to bake bread the mixing is important.


Mixing and its effects:
Mixing fulfils two functions; to evenly distribute the various ingredients and allow thedevelopment of a protein (gluten) network to give the best bread possible. Each dough has an optimum mixing time, depending on the flour and mixing method used. Too much mixing produces a dough that is very extensible with reduced elastic properties. Under mixing may cause small unmixed patches which will remain unrisen in the bread. This will give a final loaf with a poor appearance inside.

Rising (fermentation)
Once the bread is mixed it is then left to rise (ferment). As fermentation takes place the dough slowly changes from a rough dense mass lacking extensibility and with poor gas holding properties, into a smooth, extensible dough with good gas holding properties.

The yeast cells grow, the gluten protein pieces stick together to form networks, and alcohol and carbon dioxide are formed from the breakdown of carbohydrates (starch, sugars) that are found naturally in the flour. The yeast uses sugars in much the same way as we do, i.e. it breaks sugar down into carbon dioxide and water. Enzymes present in yeast and flour also help to speed up this reaction. When there is plenty of oxygen present the following reaction occurs. The energy which is released is used by the yeast for growth and activity.

In a bread dough where the oxygen supply is limited, the yeast can only partially breakdown the sugar. Alcohol and carbon dioxide are produced in this process known as alcoholic fermentation. The carbon dioxide produced in these reactions causes the dough to rise (ferment or prove), and the alcohol produced mostly evaporates from the dough during the baking process.

During fermentation each yeast cell forms a centre around which carbon dioxide bubbles form. Thousands of tiny bubbles, each surrounded by a thin film of gluten form cells inside the dough piece. The increase in dough size occurs as these cells fill with gas.


Kneading/Moulding
Any large gas holes that may have formed during rising are released by kneading. A more even distribution of both gas bubbles and temperature also results. The dough is then allowed to rise again and is kneaded if required by the particular production process being used.

During the final rising (proving) the dough again fills with more bubbles of gas, and once this has proceeded far enough the doughs are transferred to the oven for baking.


Dough Rising
General appearance - large gas holes lined with gluten with smaller holes and ingredients in between these. After two hours rising gluten strands form a lattice as the dough reaches the required size


Baking
The baking process transforms an unpalatable dough into a light, readily digestible, porous flavourful product. The physical activities involved in this conversion are complex but the fundamentals of these are explained.

As the intense oven heat penetrates the dough the gases inside the dough expand, rapidly increasing the size of the dough. This is called "ovenspring" and is caused by a series of reactions:

Gas + heat = increased volume or increased pressure.

Gas pressure inside the thousands of tiny gas cells increases with the heat and the cells become bigger. A considerable portion of the carbon dioxide produced by the yeast is present in solution in the dough. As the dough temperature rises to about 40°C, carbon dioxide held in solution turns into a gas, and moves into existing gas cells. This expands those cells and overall the solubility of the gases is reduced. The oven heat changes liquids into gases by the process of evaporation and thus the alcohol produced evaporates.

Heat also has an effect on the rate of yeast activity. As the temperature rises the rate of fermentation increases, and so does the production of gas cells, until the dough reaches the temperature at which yeast dies (approximately 46°C).

From about 60C onwards stabilisation of the crumb begins. Starch granules swell at about 60C, and in the presence of water, released from the gluten, the outer wall of the starch granule cell bursts and the starch inside forms a thick gel-like paste, that helps form the structure of the dough.

From 74C upwards the gluten strands surrounding the individual gas cells are transformed into the semi-rigid structure commonly associated with bread crumb strength. The natural enzymes present in the dough die at different temperatures during baking. One important enzyme, Alpha-amylase, the enzyme which breaks starch into sugars, keeps on performing its job until the dough reaches about 75C.

During baking the yeast dies at 46C, and so does not use the extra sugars produced between 46-75C for food. These sugars are then available to sweeten the bread crumb and produce the attractive brown crust colour.

As baking continues the internal loaf temperature increases to reach approximately 98C. The loaf is not completely baked until this internal temperature is reached. Weight is lost by evaporation of moisture and alcohol from the crust and interior of the loaf. Steam is produced because the loaf surface reaches 100C+. As the moisture is driven off, the crust heats up and eventually reaches the same temperature as the oven.

Sugars and other products, some formed by breakdown of some of the proteins present, blend to form the attractive colour of the crust. These are known as "browning" reactions, and occur at a very fast rate above 160C. They are the principal causes of the crust colour formation.

Cooling
In bakeries bread is cooled quickly when it leaves the oven. The crust temperature is over 200C and the internal temperature of the crumb about 98°C. The loaf is full of saturated steam which also must be given time to evaporate. The whole loaf is cooled to about 35C before slicing and wrapping can occur without damaging the loaf.

A moist substance like bread loses heat through evaporation of water from its surface. The rate of evaporation is affected by air temperature and the movement of cool air around the loaf. So in a bakery there are special cooling areas to ensure efficient cooling takes place before the bread is sliced and wrapped.


PRODUCTION METHODS
All conventional bread production involves measuring the ingredients; mixing and kneading the ingredients to form an extensible dough; allowing the dough to ferment under controlled conditions; kneading the fermented dough; forming the dough piece; proofing, or allowing the dough piece to ferment; and baking. There are many variations of this simple scheme.

Mixing and kneading the ingredients to form a soft, elastic mass (called developing the dough) is a critical part of the baking process. Unless the proper physical properties are obtained at this stage, the dough will be very difficult to manipulate, either by hand or by machinery, and will not produce bread of optimal volume and texture. An adequately developed bread dough will exhibit a slight sheen on the surface but will be only slightly sticky to the touch. When the dough is stretched out to a thin film, it will not tear readily and will have a translucent, webbed appearance when viewed against the light.

The second kneading process collapses the expanded dough piece so that most of the leavening gas is pressed out of it. This is done to prevent the formation of large gas bubbles, which mar the appearance of the loaf and reduce the quality of the bread. After the initial fermentation, the bulk dough mass is cut into pieces calculated to yield the desired size of roll or loaf. In one type of bread making, the dough is deposited into the pans immediately after it has been mixed. The panned or rounded dough pieces then undergo a second, and sometimes a third, fermentation, during which the leavening gas generated by the yeast causes them to expand considerably.

Bread and rolls can be baked in pans or on sheets; the latter method produces the so-called hearth breads. Most commercial ovens for large-scale production are of the tunnel type, in which multiple assemblies of loaf pans or sheets are carried through long baking chambers indirectly heated by gas, oil, or electricity.