Carbonate leavening

BAKERY PROCESSES AND LEAVENING AGENTS - CHEMICAL LEAVENING AGENTS] (Vol 3) -as carbon fiber precursors [CARBON AND GRAPHITE FIBERS] (Vol 5)... 

Phosphoric Acid. The only inorganic acid used for food appkeations is phosphoric acid [7664-38-2] H PO, which is second only to citric acid in popularity. The primary use of phosphoric acid is in carbonated beverages, especially root beer and cola. It is also used for its leavening, emulsification, nutritive enhancement, water binding, and antimicrobial properties. Eood-grade phosphoric acid is produced by the furnace method. Elemental phosphoms is burned to yield phosphoms pentoxide which is then reacted with water to produce phosphoric acid (see Phosphoric acid and the phosphates) (12). 

Cream of tartar is used in baiting powder and in prepared baiting mixes (see Bakery processes and leavening agents). Its limited solubihty at low temperatures inhibits the reaction with bicarbonate until baiting temperature is reached, thus releasing a significant portion of the carbon dioxide at the optimum time. 

Another requirement for proper leavening is the presence of a protein matrix sufftciendy elastic to trap small carbon dioxide bubbles. Wheat gluten fulfills this requirement. Rye protein is less suitable and the proteins of other cereals, eg, rice, oats, or com, are practically useless. 

There are essentially two components in a chemical leavening system bicarbonate that suppHes carbon dioxide gas, and an acid which triggers the Hberation of carbon dioxide from bicarbonate upon contact with moisture (see Carbon dioxide). 

Other bicarbonates of considerable commercial importance are ammonium bicarbonate [1066-33-7] and potassium bicarbonate [298-14-6]. These compounds are decomposed by the oven heat, Hberating ammonia, carbon dioxide, and water to faciUtate leavening action. Their uses are limited to low moisture products such as cookies and crackers. 

A number of acidic phosphates which vary in their rate of reaction are available for use in a wide variety of bakery appHcations. These acids, which include monocalcium phosphate, sodium aluminum phosphate, and sodium acid pyrophosphate, release carbon dioxide at a controlled rate to give a certain fraction prior to baking the remaining fraction is released at a specific time during baking. Controlled releasing of carbon dioxide at the time it is needed can also be achieved by a mixture of different types of leavening acids. 

Fumaric acid is used in combination with sodium bicarbonate to create delayed-action leavening agents (something that produces carbon dioxide gas to make breads rise). Since it only dissolves in warm water, the leavening action is delayed until the bread starts to bake. 

Sodium bicarbonate is used as a leavening in breads, as a stomach antacid, as a buffering agent to adjust the acidity or alkalinity of a product, as a mild abrasive in toothpaste, and as an odor absorber. Sodium bicarbonate reacts with acids to release carbon dioxide gas. 

Common acidic ingredients include vinegar, lemon juice, sour milk, buttermilk, yogurt, tart fruits, and cream of tartar. Commercial bakeries often use ammonium bicarbonate or ammonium carbonate as a leavening agent. The gas-producing reaction with ammonium bicarbonate actually generates both carbon dioxide gas and ammonia gas ... 

The distinctive aroma of ammonia is often apparent in bakeries but not in the final product. Bakers yeast performs its leavening function by fermenting such sugars as glucose, fructose, maltose, and sucrose. The principal products of the fermentation process are carbon dioxide gas and ethanol, an important component of the aroma of freshly baked bread. The fermentation of the sugar, glucose—an example of a decomposition reaction — is given by the equation in Fig. 5.19.1. 

Yeast is the leavening agent in bread and yeast raised wafers. Carbon dioxide produced by the yeast not only causes bubbles to form but also dissolves, reducing the pH. The other major product of yeast action, ethyl alcohol, boils away during the cooking phase. 

Chemical leavening takes place when carbon dioxide is produced chemically rather than biochemically. Typically, this involves treating sodium bicarbonate with an acid such as sodium acid... 

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. 

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. 

Sodium carbonate (Na CO ) is the eleventh most used industrial chemical in the United States. It is commonly used as a bleaching agent and is manufactured in a two-step process. First, ammonia is combined with carbon dioxide to form sodium chloride and water, which reacts to form sodium bicarbonate and ammonium chloride (NH + CO + NaCl + H O —> NaHCOj + NH Cl). Sodium bicarbonate, commonly known as baking soda, is used as a leavening agent in baking, as an antacid to relieve stomach acid, and as a component for fire extinguishers. The second step is known as the Solvay process, wherein the sodium bicarbonate is heated and converted into sodium carbonate (NaHCO A— Na CO + H O + CO ). 

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