Principles of Cereal Science and Technology, Third Edition
Wheat is unique among the cereals in that its flour can form dough when mixed with water. In addition, wheat dough retains the gas produced during fermentation or by chemical leavening and thus gives a leavened product. These two characteristics of wheat flour dough are responsible for the popularity of wheat products.
The present chapter deals with dough-based yeast-leavened products. By its very nature, the discussion is restricted primarily to wheat flour systems. It is unusual to find yeast-leavened products made from other cereal flours anywhere in the world, except for those based on rye flour. Indeed, rye flour is also used to make yeast-leavened products in some parts of the world. However, in general, yeast-leavened products made solely from rye flour are rare. Rye tends to be used as a flavoring agent in wheat-flour-based recipes rather than as the most important dough ingredient.
The most popular yeast-leavened product by far is bread. The amount of bread consumed in the world is truly staggering, as is the wide array of sizes, shapes, textures, and tastes that bread comes in. Breads vary in size from small bread sticks to loaves weighing several pounds or kilos. Crust color and texture can vary from the thin, white crust of Chinese steam bread to the thick, black crust of pumpernickel. The reasons for the existence of such variety are complex and difficult to sort out. Many of them have to do with tradition, the other foods consumed, and the proportion of bread in the diet. Two factors of great importance in the industrialized world are convenience and economics. Supermarket bread is more convenient and generally less expensive than bread from retail bake shops. However, it may not reach the supermarket shelves within the first 24 h after baking and thus is not as fresh. In addition to meeting the consumer demand for convenience, in the industrialized world, the breadmaking industry needs to provide products that remain soft, and thus desirable, for many days after production. In some parts of the world, bread is consumed within a few hours and most certainly within the first day after it is produced. Much of such bread is truly inedible the day after baking. Another factor is the difference in quality of the bread wheats grown in North America, Australia, Argentina, Russia, Hungary, the Middle East, and the Punjab area of India on the one hand and the quality of, for instance, the typical European wheats on the other hand.
In what follows, different aspects of breadmaking processes, the raw materials used, and the roles of their specific components are discussed, as are some quality aspects of the products obtained. Although the focus is mainly on bread, other products are also considered.