Bakery Processes, Yeast‐Raised Products

The U.S. baking industry comprises an important portion of the food industry, the nation's largest business. Another source of bakery foods is the food service industry, establishments, including restaurants, hospitals, and prisons. Differentiated from the quickly perishable bakery foods are the dry bakery products such as cookies, crackers, pretzels, and ice cream cones. These latter items possess a much longer shelf life and may be distributed over a wider area from typically very large manufacturing facilities. Per capita consumption of all bakery products in the United States was about 50 kg in 1990. Bread accounted for about 45% of this consumption, while all yeast-leavened items comprised approximately 74% of the total. The role of baker's yeast (Saccharomyces cerevisiae) in producing leavened bread depends on two factors: the ability of yeast to generate carbon dioxide and alcohol through the breakdown of simple sugars, and the unique ability of wheat flour proteins to form films in dough that trap evolved gases. Basic bread is made with flour, water, salt, and yeast. Product variety is achieved by incorporating varying amounts of additional ingredients; by altering the breadmaking process; by shaping or cutting or putting toppings on the dough prior to baking; or by the method of baking. Chemical leaveners (primarily baking powders) are utilized in cakes, cookies, some crackers, refrigerated dough, and quick bread manufacturing. These products make up roughly 39% of the value of the baking industry's total production. A great many ingredients may be utilized in the production of innumerable bakery foods. Key ingredients include flour, yeast, yeast foods, sugar, shortening, surfactants, milk and milk replacers, eggs, salt, water, enzymes, mold inhibitors (antimycotics), flavorings, and enriching ingredients. Mills ship flour in bulk directly to large commercial bakeries via specially designed railroad cars or trucks. This flour is transferred pneumatically to bins in the plant, from which it is conveyed (also pneumatically) to the mixing process as required. Smaller plants may instead use a tote bin system of bulk handling. Flour used in small quantities, is delivered in multiwalled paper bags. Most of the sugar used by commercial bread bakers is in syrup form; high fructose corn syrup is primarily used. Shortening and oil can also be handled in bulk. If the shortening is plastic, it is melted so that it can be pumped through pipes. Yeast (compressed and cream) and other perishable ingredients are stored under refrigeration; freezers are required for frozen eggs and fruits. Principal process categories used in the manufacture of yeast-raised products include the sponge and dough method, the straight dough method, and highly accelerated short-time methods that include frozen dough processing, continuous mix, and liquid ferment processes. Considerable variation exists among commercial bakeries within each of these categories. Principal differences are that special makeup machinery to produce the various shapes, and finishing equipment to fill and ice sweet roll and coffee cake units, are required. Federal standards of identity exist for white bread, enriched bread, milk bread, raisin bread, and whole wheat bread that move in interstate commerce. Most bakery foods sold in the United States are produced by large commercial bakeries engaged in interstate commerce; nearly all bread and rolls necessarily conform to the federal standards. Most specialty breads, such as rye, multigrain, pita, and French, are not covered by standards of identity. All ingredients permitted in standardized bakery foods are considered optional ingredients and therefore must be declared in ingredient legends on bread wrappers. Since 1975, the FDA has required that all enriched bread-type products bear nutrition labeling. Keywords: Yeast; Chemical leavening; Ingredients; Bulk ingredient handling; Bread production; Dough processes; Frozen dough; Standard of identity; Bakery products; Bread