Levain is a French word that refers to a substance that causes the volume of dough or batter to rise through incorporation of air. The function of leavening agents is to aerate the dough or batter to make it light and porous. The porosity of batter results in good volume, tender crumb, uniform cell and good aesthetic qualities. Leavening can be done biologically using yeast, mechanically by mixing, whipping or beating and chemically using baking powder and baking soda. Combining different leavening methods impart an adverse effect, as it may either lead to incorporation of excess air or kill the effect of one agent over the other. Leavening is a process of bringing expansion of volume in baked products. Leavening effect is brought by combinations of air, steam or carbon dioxide produced by yeasts or chemical substances.
Air incorporated during mixing begins to expand when heated during baking. Whipped egg (air incorporated) when added to batter with minimum manipulation brings this effect. Steam causes an appreciable leavening action because a volume of water in a batter or dough expands 1800 times when it is converted to steam during baking.
Yeast such as Saccharomyces cerevisiae grow and multiply under controlled conditions depending upon available nutrients, temperature, relative humidity, available water and pH and release gases. Yeast is used to leaven or raise the dough for bread and rolls. It gives a distinctive aroma and flavor to the product. This brings about textural changes in the products as in case of breads. Yeast is available in fresh, compressed form (which needs to be stored under refrigerated conditions) and also as active dry yeast.
Chemical leavening agents that produce gases during baking are mixtures of acid and alkalis that effect release of carbon dioxide during baking. Baking Soda (Sodium bicarbonate) is the common alkali in baking powders along with the acid ingredient such as sodium acid pyrophosphate or monocalcium phosphate, sodium aluminum phosphate, tartarate and sulphate phosphates. Baking soda releases carbon dioxide on being exposed to moisture and acid. In baking, it is used for leavening or giving volume to quick breads, cookies and cakes. Hence soda and acid are termed active ingredients in baking powder. These two active substances are suspended in starch which keeps them separated and keep reaction of the acid and soda to a minimum in the package. Starch also adds to the body of the baking powder. The volume and texture of the product depend largely on the amount added to the batter or dough. Besides damaging the volume and texture, excess use of baking soda leaves an after- taste and gives a light color to the finished product.
Salt:Primarily used for flavor in baked products. It forms a taste contrast in the background, which enhances the sweetness from the sugars present in the dough or batter. It has a water binding or hygroscopic capability enabling it to regulate fermentation. Too little salt causes the dough to ferment too fast and wild, while too much salt slows down the fermentation process. Salt is also a toughening agent because it strengthens the gluten (protein). In proper amounts, salt produces good grain and texture
Last modified: Thursday, 15 December 2011, 10:22 AM
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