Name ______General Chemistry
Date ______
Leavening Agents
A leavening agent, also known as a raising agent, is any one of a number of substances used in doughs and batters that causes a foaming action that lightens and softens. The leavening agent incorporates gas bubbles into the dough. Most leavening agents are synthetic chemical compounds, but carbon dioxide can also be produced by biological agents. When a dough or batter is mixed, the starch in the flour mixes with the water in the dough to form a matrix which then gelatinizes and "sets"; the holes left by the gas bubbles remain. Chemical leaveners are mixtures or compounds that release gases when they react with each other, with moisture, or with heat. Most are based on a combination of acid and a salt of bicarbonate (HCO3−). After they act, these compounds produce carbon dioxide (CO2) and leave behind a chemical salt. Chemical leaveners are used in quick breads, cookies and cakes. Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol. Record observations of the following commonly used leavening agents.
Leavening process Bubble height Bubble height after 3 Bubble height immediately minutes after 10 minutes Yeast, sugar and water Baking powder and water Baking soda and water Baking soda and vinegar
What gas to leavening agents produce?
Is baking soda alone a good leavening agent? Explain.
How is the leavening effect of yeast different from baking powder or baking soda? Why might baking powder be preferred as a leavening agent instead of yeast?
Why might yeast be preferred as a leavening agent instead of baking powder or soda?
Which of the leavening agents that was used is a living organism?