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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Saccharomyces cerevisiae est une espèce de levures employée notamment dans la fermentation de la bière. Elle occupe une place particulière parmi les ferments, levains et levures utilisés depuis la Haute Antiquité : de nombreux peuples, tels que les Égyptiens, Babyloniens ou Celtes, l’utilisaient pour la fabrication de boissons fermentées, du pain, du kéfir, du vin et de la bière de fermentation haute.
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.
vignette|Levures boulangère (gauche) et chimique (droite) La levure chimique, poudre à lever, poudres levantes ou poudre à pâte (au Canada) est un mélange composé essentiellement d'un agent basique (tel que le bicarbonate de sodium), un agent acide (acide tartrique, pyrophosphate de sodium) et un agent stabilisant (tel que l'amidon de blé ou de maïs), se présentant sous forme de poudre blanche et servant à faire gonfler pains et pâtisseries.
S'engage dans l'utilisation de la fermentation pour la production de protéines alternatives, en mettant l'accent sur des technologies alimentaires durables et innovantes.