Starch bread doughs

You may have used yeast to make bread dough or pizza dough rise. Dry yeast is the dormant form of a single-celled fungus that, when given favorable living conditions and food in the form of a carbohydrate, begins to break down the carbohydrate. One of the products of respiration is carbon dioxide. In this MiniLab, you will mix yeast with a disaccharide, sucrose, and with a polysaccharide, the starch in flour, and compare the rates at which carbon dioxide is produced. 

Calcium stearoyl-2-lactylate—a recognized bread dough conditioner (24)—is known to complex with certain water-soluble fractions of wheat protein (3), but there is little hard evidence pointing to a direct interaction between it and gluten proteins on the order of that seen between the nonionic surfactants and gliadin. Some evidence (25) suggests that calcium stearoyl-2-lactylate interacts with gluten proteins in the presence of starch. 

Analysis of bread dough before and after fermentation showed that the quantity of starch and dextrin suffered no loss. 

Bread is made from water plasticized wheat flour, which in turn consists of ground-up wheat seeds. Dry flour consists of approximately 12% of protein, 87% of starch, and approximately 1% of everything else, such as minerals and salts. Since both the protein and the starch are polymeric, bread dough and... 

Wheat starch is composed of two components itself amylose, a linear, amorphous polymer and amylopectin, a branched, semicrystaUine polymer (10). The protein is known as gluten, also composed of two polymers, gliadin, a low-molecular-weight, soluble polymer and glutenin, a high-molecular-weight, cross-linked, elastic polymer primarily responsible for the viscoelastic properties of bread doughs. 

Bread dough is prepared by mixing water and flour (70 30 w/w). Water upttike, which depends on flour type, predetermines most of the subsequent reactions. A high water upttike favors the mobility of all the constituents involved in reactions, e. g., enzymatic degradation of starch into reducing sugars (Fig. 15.43). 

Small, but sometimes also relatively large, amounts of maltose are typically found in most foods. Bread dough contains maltose formed by hydrolysis of starch by yeast Saccharomyces cerevisiae) enzymes and by enzymes present in the flour. At the beginning of the fermentation, its content increases due to the hydrolysis of starch. After the preferred fermentation of glucose and fructose, the maltose content decreases, as it is also partially fermented by yeast. The level of maltose present in bread is 1.7-4.3%. 

Sodium stearoyl-2-lactylate An emulsifier and dough conditioner widely used in the baking industry. It is used to improve the tolerance of bread dough to processing, to improve gas retention, and maintain crumb sofmess. It reduces the rate of starch retrogradation or staling. 

Rye Proteins. While rye is the only European cereal able to completely replace wheat in bread, rye protein is not as effective as wheat protein. One reason for this is that as much as 80% of the protein in a rye sour dough is soluble compared with 10% of soluble protein in a wheat dough. One factor that inhibits the formation of a gluten-like complex is the 4-7% of pentosans present, which bind water and raise the viscosity of the dough. The crumb structure is then formed from the pentosans in combination with the starch. 

Conventional improvers are not used in rye bread but additives are sometimes used to increase the water absorption of the dough. Examples are polysaccharide gums such as guar and locust bean gum as well as pregelatinised potato flour, rice starch or maize starch. 

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