Learning Objectives: 1. Describe the role of gluten in making bread 2. State the difference between white flour and whole wheat flour 3. State the importance of salt when making baking products with yeast 4. Learn how to measure using measuring spoons and measuring cups 5. List 3 important mixing procedures for making yeast dough 6. State why milk is scalded before being used in making bread.
Yeast breads are baked dough that is usually made from flour, water, salt, sugar, and yeast. Bread flour is made from varieties of wheat containing proteins that produce very strong gluten. All-purpose flour is made from varieties with less gluten.
Gluten: Gluten is an elastic protein substance responsible for most of the structure in bakery products. It traps leavening gases and consequently affects the volume of the final product. Too much gluten makes a tough final product, and too little gluten results in a weak product that can fall.
White Flour. The milling process to make white flour separates the wheat germ (the interior fat- containing kernel), the starchy layer, and the external bran. The bran (the husk covering of the wheat) is the primary source of fiber in all types of flour.
Whole Wheat Flour. Whole wheat flour produces breads that are high in fiber content. Whole wheat flour is made by grinding the entire wheat grain, including the bran and germ. Because the wheat germ is included, this flour becomes rancid very easily and has a shorter shelf life than does bread or all- purpose flour. However, refrigeration will extend the life of the flour. Bread made solely from 100% whole wheat flour will be much heavier than white bread. This heavy, dense structure forms because the sharp edges of the bran cut the gluten strands. In addition, as the bran fiber increases, proteins decrease, because bran does not contain gluten proteins, and this results in a lower volume.
Mixing Yeast Bread Dough. To make a high-quality bread, it is important to use the correct mixing technique. There are three important mixing procedures for all methods of preparing yeast dough. • Blend all ingredients evenly. • Develop the gluten for structure and smooth appearance. • Distribute the yeast evenly throughout the dough
Milk in Yeast Doughs. To increase the yeast dough volume in all three methods, milk should be scalded (heated to 187 F). Scalding the milk kills any microorganisms that might prevent the yeast from growing. Milk proteins begin to coagulate during scalding, allowing them to help build structure in the bread. Even when dry milk is reconstituted in the modified-straight-dough method, the milk should be scalded.
Scalded fresh milk can be substituted for the scalded reconstituted dry milk and added to the dough with the other liquids. In quantity food production, the advantages of the extra volume that is possible when milk is scalded should be compared with the efficiency by eliminating the scalding process. Salt in Yeast Doughs. Salt also must be carefully measured for all yeast bread recipes. Salt not only adds flavor but is also a major control of the yeast growth. It cannot be reduced in an already established recipe without causing excessive yeast growth.
Proofing Yeast Doughs. The proofing (rising) that occurs in yeast doughs is the result of yeast, the leavening agent. Yeast ferments the sugar in the recipe to form carbon dioxide, alcohol, and water. The carbon dioxide remains in the product until it is baked, forming the necessary pockets of air that leaven and proof the bread. This process is called proofing in yeast breads. As more and more carbon dioxide is formed, the pockets grow larger. As the carbon dioxide heats in the oven, it expands and exerts pressure that causes the dough to expand. The alcohol produced by fermentation evaporates during baking.
The sucrase enzyme produced by the yeast breaks down any sucrose (table sugar) in the formulation into fructose and glucose, which are simple sugars that yeast can ferment. When the recipe does not have added sugar, the yeast will use glucose (sugar that is released from the starch in the flour). Because the glucose must be released by an enzyme present in the flour, doughs without added sugar take longer to proof.
The desired temperature for proofing is 85–95 F. Higher temperatures will shorten proofing time but will diminish the quality of the flavor and texture. Caution should be taken to ensure that the proofing temperature never exceeds 110 F. Otherwise, the yeast will be killed, and the bread will not rise to full volume.
Baking Yeast Breads. Although oven temperatures eventually kill yeast, yeast produces additional carbon dioxide until the internal temperature reaches 110 F. The increase in volume that occurs in the oven is called oven spring. Preheating controls the amount of oven spring and ensures the yeast is killed before the outer crust is baked. Where this does not happen, the bread continues to proof and the crust splits.
Due to the delicate structure of baked products, the oven should not be opened to check for doneness until close to the end of the expected baking time. Before this, the tender and weak state of the bread could cause the product to fall. Yeast breads usually are done when they are golden brown, produce a hollow sound when tapped.
Learning Activity: Find a recipe for making homemade bread and make it with your children. Information adapted from: FOOD PREPARATION STUDY COURSE (2002) Fourth Edition, Iowa Academy of Nutrition and Dietetics (formerly Iowa Dietetic Association) Shirley A. Gilmore, Ph.D., R.D., L.D