Leavening agent

In cooking, a leavening agent (ˈlɛvənɪŋ) or raising agent, also called a leaven (ˈlɛvən) or leavener, is any one of a number of substances used in doughs and batters that cause a foaming action (gas bubbles) that lightens and softens the mixture. An alternative or supplement to leavening agents is mechanical action by which air is incorporated (i.e. kneading). Leavening agents can be biological or synthetic chemical compounds. The gas produced is often carbon dioxide, or occasionally hydrogen. When a dough or batter is mixed, the starch in the flour and the water in the dough form a matrix (often supported further by proteins like gluten or polysaccharides, such as pentosans or xanthan gum). The starch then gelatinizes and sets, leaving gas bubbles that remain. Saccharomyces cerevisiae producing carbon dioxide found in: baker's yeast Beer barm (unpasteurised—live yeast) ginger beer kefir sourdough starter Clostridium perfringens producing hydrogen found in salt-rising bread Chemical leavens 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 (usually a low molecular weight organic acid) and a salt of bicarbonate (HCO3−). After they act, these compounds leave behind a chemical salt. Chemical leavens are used in quick breads and cakes, as well as cookies and numerous other applications where a long biological fermentation is impractical or undesirable. Chemical leavening using pearl ash as a leavening agent was mentioned by Amelia Simmons in her American Cookery, published in 1796. Since chemical expertise is required to create a functional chemical leaven without producing off-flavors from the chemical precursors involved, such substances are often mixed into premeasured combinations for maximum results. These are generally referred to as baking powders. Sour milk and carbonates were used in the 1800s. The breakthrough in chemical leavening agents occurred in the 1930s with the introduction of monocalcium phosphates (Ca(H2PO4)2).

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Baking powder

Baking powder is a dry chemical leavening agent, a mixture of a carbonate or bicarbonate and a weak acid. The base and acid are prevented from reacting prematurely by the inclusion of a buffer such as cornstarch. Baking powder is used to increase the volume and lighten the texture of baked goods. It works by releasing carbon dioxide gas into a batter or dough through an acid–base reaction, causing bubbles in the wet mixture to expand and thus leavening the mixture.

Saccharomyces cerevisiae

Saccharomyces cerevisiae (ˌsɛrəˈvɪsi.iː) (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungus microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been originally isolated from the skin of grapes. It is one of the most intensively studied eukaryotic model organisms in molecular and cell biology, much like Escherichia coli as the model bacterium. It is the microorganism behind the most common type of fermentation.

Barm

Barm, also called ale yeast, is the foam or scum formed on the top of a fermenting liquid, such as beer, wine, or feedstock for spirits or industrial ethanol distillation. It is used to leaven bread, or set up fermentation in a new batch of liquor. Barm, as a leaven, has also been made from ground millet combined with must out of wine-tubs and is sometimes used in English baking as a synonym for a natural leaven (sourdough). Various cultures derived from barm, usually Saccharomyces cerevisiae, became ancestral to most forms of brewer's yeast and baker's yeast currently on the market.

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Delves into the use of fermentation for alternative protein production, emphasizing sustainable and innovative food technologies.