Chemically leavened products

In chemically leavened products the same things occur except that the carbon dioxide is chemically produced. The rate and temperature at which the carbon dioxide is produced depends on the choice of chemical leavening agents. 

Dakery products may be classified into two main groups—those leavened by yeast and those by chemical or physical means. Yeast-raised goods include bread, rolls, sweet rolls, raised doughnuts, and crackers. Chemically leavened products include most cakes, cake doughnuts, pastries, and cookies. Foam-type cakes such as angel food and sponge cake are physically leavened by aeration. Pies represent a separate class. 

Wheat is the only cereal that possesses functional gluten. The flour, upon hydration and the mechanical work of mixing, forms a cohesive and elastic dough suited for production of yeast-leavened breads, chemical-leavened bakery goods, and pasta (Pomeranz 1988, Kulp and Ponte 2000, Owens 2001). Hard wheats are preferred for production of yeast-leavened breads, whereas soft wheats are used in the manufacture of chemically-leavened products such as muffins, cookies, and cakes. Durum wheats are almost exclusively used for the manufacture of long and short pasta products (Fabriani and Lintas 1988). 

Wheat is the most diverse cereal in terms of food uses and the cereal that is used to produce the most commercial products. This is because wheat is the only cereal that has functional gluten and is commercially available in three contrasting classes with different end uses. The soft, hard, and durum wheats are popular worldwide, especially in industrialized countries. The first two types are generally milled into flour, whereas the last is made into semolina (Chapter 7). The main uses of these milled fractions are for the production of a wide array of yeast- and chemical-leavened products, and short and long pastas. The major food uses of different wheat flours and semolina are depicted in Figure 10.1. 

Baked or cake donuts are classified as chemically leavened products. Compared to yeast-leavened donuts, these are quick to prepare and generally baked, although some are fried. Baked donuts have lower oil content and therefore less calories and longer shelf-life expectations. Baked donuts are produced from soft or all-purpose wheat flours that are mixed with water, a combination of chemical leavening agents... 

Benzoates. The sodium and potassium salts of ben2oic acid [65-85-0], C2H 02, ate most effective against yeast and mold. They ate used in beverages, fmit products, chemically leavened baked goods, and condiments. Owing to their inhibitory effect on yeast, they cannot be used in yeast-leavened products. Potassium ben2oate was developed for use in reduced-sodium products. Ben2oates ate permitted for use in foods up to a level of 0.1% (76). 

Bakery Products. Sorbates are used in and/or on yeast-raised and chemically leavened bakery products. The internal use of sorbates in yeast-raised products at one-fourth the amount of calcium—sodium propionate that is normally added provides a shelf life equal to that of propionate without adversely affecting the yeast fermentation. Sorbates added at one-tenth the propionate level reduce the mix time by 30% (126). This internal treatment combined with an external spray of potassium sorbate can provide the same or an increased shelf life of pan breads, hamburger and hot-dog buns, English muffins, brown-and-serve roUs, and tortillas. The total sorbate useful in or on these baked goods ranges from 0.03 wt % for pan breads to 0.5 wt % for tortillas 0.2—0.3 wt % sorbic acid protects chemically leavened yellow and chocolate cakes (127). Emit-pie fillings and icings can be protected with 0.03—0.1 wt % sorbates. 

Yeast-raised products, Chemical leavening agents,... 

While it is possible to leaven products either with yeast or chemical leavening agents, ultimately the product is expanded by gases and vapours. In a yeast raised product the expansion is caused by carbon dioxide and ethanol while in a chemically raised product the carbon dioxide is produced chemically. 

Acidulants. The other component of any system of chemical leavening based on sodium hydrogen carbonate is an acid. The original acidulants were sour milk (lactic acid), vinegar (acetic acid), lemon juice (citric acid) and cream of tartar (potassium acid tartrate). All of these will react immediately on mixing so that the carbon dioxide is released straight away. The product had to be baked before the carbon dioxide escaped from the batter or product. The only delay possible was that allowed by the batter viscosity. 

Raidl and Klein (43) substituted 5, 10, and 15% field pea flour in chemically leavened quick bread. The viscosity of the pea flour batters was significantly lower than either the wheat control or soy containing batters. The starch composition of the pea flour and lower water absorption properties of the protein could have affected the viscosity. Volumes of pea flour loaves were lower than the control and soy loaves. Most of the sensory characteristics of the field pea loaves were similar to those of the control quick breads. However, all flavor scores were significantly lower for pea flour products, since they had a recognizably beany or off-flavor. 

To reveal the contribution of yeast in the formation of the Acp the amount of Acp in a bread crust from yeast-fermented dough was compared to the amount present in the crust of a chemically leavened bread. The production of Acp was reduced from 34 jig/kg to 9.6 jug/kg flour when the yeast was replaced by a commercial leavening agent. 

In chemically-leavened flour, In the presence of liquid, the acid of the phosphate reacts with baking soda to produce a leavening gas, carbon dioxide—the same as the yeast organisms produce in yeast-raised products. Additionally, the calcium and phosphorus improve the nutritive qualities of the flour. 

According to end use, wheat is classified as soft, hard, and durum. The first two classes are almost always dry-milled into refined flour for the manufacturing of fermented and chemical-leavened bakery products such as breads, cakes, crackers, cookies, and flour tortillas (Figure 1.8). Durums are dry-milled into coarse refined meals called semolina, ideally suited for manufacturing of long and short pasta products. Rye flour is usually mixed with wheat flour for the production of fermented breads including sour breads, especially in Germany, Poland, Ukraine, and other European countries. 

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