Some Extra Knowledge...

MIXING AND GLUTEN
DEVELOPMENT

Gluten is a substance made up of proteins present in wheat flour. It gives structure and strength to baked goods. In order for gluten to be developed, the proteins must first absorb water. Then,as the dough or batter is mixed or kneaded,the gluten forms long,elastic strands. As the dough or batter is leavened, these strands capture the gases in tiny pockets or cells, and we say the product rises. When proteins are heated, they coagulate.This means they become firm or solidify.You are familiar with this process in the case of eggs, which are liquid when raw but firm when cooked. This process is also important in baking.When dough or batter is baked, the gluten, like all proteins,coagulates or solidifies and gives structure to the product.

CONTROLLING GLUTEN

Flour is mostly starch, as you know, but it is the protein or gluten content, not the starch, that concerns the baker most. Gluten proteins are needed to give structure to baked goods. Bakers must be able to control the gluten, however. For example, we want French bread to be firm and chewy, which requires much gluten. On the other hand,we want cakes to be tender,which means we want very little gluten development. Ingredient proportions and mixing methods are determined, in part, by how they affect the development of gluten.The baker has several methods for adjusting gluten development:
1. Selection of flours Wheat flours are classified as strong or weak, depending on their protein content. Strong flours come from hard wheat and have a high protein content. Weak flours come from soft wheat and have a low protein content. Thus, we use strong flours for breads and weak flours for cakes. Only wheat flour develops enough gluten to make bread.To make bread from rye or other grains, the formula must be balanced with some highgluten flour, or the bread will be heavy.
2. Shortening Any fat used in baking is called a shortening because it shortens gluten strands. It does this by surrounding the particles and lubricating them so they do not stick together.Thus, fats are tenderizers.

A cookie or pastry that is very crumbly, which is due to high fat content and little gluten development, is said to be short. You can see why French bread has little or no fat, while cakes contain a great deal.
3. Liquid Because gluten proteins must absorb water before they can be developed, the amount of water in a formula can affect toughness or tenderness. Pie crusts and crisp cookies, for instance, are made with very little liquid in order to keep them tender.
4. Mixing methods In general, the more a dough or batter is mixed, the more the gluten develops.Thus, bread doughs are mixed or kneaded for a long time to develop the gluten. Pie crusts, muffins, and other products that must be tender are mixed for a short time. It is possible to overmix bread dough,however. Gluten strands will stretch only so far. They will break if the dough is overmixed.

THE BAKING PROCESS

The changes to a dough or batter as it bakes are basically the same in all baked products, from breads to cookies and cakes. You should know what these changes are so you can learn how to control them. The stages in the baking process are as follows:
1. Formation and expansion of gases The gases primarily responsible for leavening baked goods are carbon dioxide, which is released by the action of yeast and by baking powder and baking soda; air, which is incorporated into doughs and batters during mixing; and steam, which is
formed during baking. Some gases—such as carbon dioxide in proofed bread dough and air in sponge cake batters—are already present in the dough. As they are heated, the gases expand and leaven the product. Some gases are not formed until heat is applied.Yeast and baking powder form gases rapidly when first placed in the oven. Steam is also formed as the moisture of the dough is heated. Leavening agents are discussed in greater detail in the next chapter.
2. Trapping of the gases in air cells As the gases are formed and expand,they are trapped in a stretchable network formed by the proteins in the dough.These proteins are primarily gluten and sometimes egg protein. Without gluten or egg protein, most of the gases would escape, and the product would be poorly leavened.Breads without enough gluten are heavy.
3. Gelatinization of starches The starches absorb moisture,expand,and become firmer. This contributes to structure. Gelatinization of starches begins at about 140°F (60°C).
4. Coagulation of proteins Like all proteins, gluten and egg proteins coagulate or solidify when they reach high enough temperatures. This process gives most of the structure to baked goods. Coagulation begins when the temperature of the dough reaches about 165°F (74°C). Correct baking temperature is important. If the temperature is too high, coagulation starts too soon, before the expansion of gases reaches its peak. The resulting product has poor volume or a split crust. If the temperature is too low, the proteins do not coagulate soon enough, and
the product may collapse.
5. Evaporation of some of the water This takes place throughout the baking process. If a baked product of a specific weight is required, allowance must be made for moisture loss when scaling the dough. For example, to get a 1-lb loaf of baked bread, it is necessary to scale about 18 oz dough.The percentage of weight loss varies greatly, depending on such factors as proportion of surface area to volume, baking time, and whether the item is baked in a pan or directly on the oven hearth.
6. Melting of shortenings Different shortenings melt and release trapped gases at different temperatures, so the proper shortening should be selected for each product.
7. Crust formation and browning A crust is formed as water evaporates from the surface and leaves it dry. Browning occurs when sugars caramelize and starches and sugars undergo certain chemical changes caused by heat. This contributes to flavor. Milk, sugar, and egg increase browning.

STALING

Staling is the change in texture and aroma of baked goods due to a change of structure and a loss of moisture by the starch granules. Stale baked goods have lost their fresh-baked aroma and are firmer, drier, and more crumbly than fresh products. Prevention of staling is a major concern of the baker, because most baked goods lose quality rapidly. Staling begins almost as soon as the baked items are taken from the oven. There are, apparently, two factors in staling. The first is loss of moisture, or drying.This is apparent, for example,when a slice of fresh bread is left exposed to air. It soon becomes dry to the touch. The second factor is a chemical change in the structure of the starch.This process, called starch retrogradation, occurs even when little or no moisture is lost.This means that even a well-wrapped loaf of bread will eventually stale. Chemical staling is rapid at refrigerator temperatures, but it nearly stops at freezer temperatures. Thus, bread should not be stored in the refrigerator. It should be left at room temperature for short-term storage or frozen for longterm storage.
Chemical staling, if it is not too great, can be partially reversed by heating. Breads, muffins, and coffee cakes, for example, are frequently refreshed by placing them briefly in an oven. Remember, however, that this also results in more loss of moisture,so the items should be reheated only just before they are to be served. Loss of crispness is caused by absorption of moisture, so, in a sense, it is the opposite of staling.The crusts of hard-crusted breads absorb moisture from the crumb and become soft and leathery. Reheating these products to refresh them not only reverses chemical staling of the crumb but also recrisps the crusts. Loss of crispness is also a problem with low-moisture products such as cookies and pie crusts. The problem is usually solved by proper storage in airtight wraps or containers to protect the products from moisture in the air. Prebaked pie shells should be filled as close to service time as possible. In addition to refreshing baked goods in the oven, three main techniques are used to slow staling:
1. Protecting the product from air Two examples of protecting baked goods are wrapping bread in plastic and covering cakes with icing, especially icing that is thick and rich in fat. Hard-crusted breads, which stale very rapidly, should not be wrapped, or the crusts will quickly become soft and leathery. These bread products should always be served very fresh.
2. Adding moisture retainers to the formula Fats and sugars are good moisture retainers, so products high in these ingredients keep best. Some of the best French bread has no fat at all, so it must be served within hours of baking or it will begin to stale. For longer keeping, bakers often add a very small amount of fat and/or sugar to the formula.
3. Freezing Baked goods frozen before they become stale maintain quality for longer periods. For best results, freeze soon after baking in a blast freezer at −40°F (−40°C), and maintain at or below 0°F (−18°C) until ready to thaw. Breads should be served very quickly after thawing. Frozen breads may be reheated with excellent results if they are to be served immediately. Refrigeration, on the other hand, speeds staling. Only baked goods that could become health hazards, such as those with cream fillings, are refrigerated.