hefmiddel

Hefmiddel, or leavening agent, is a substance or organism used to cause fermentation and gas production in dough and batter, enabling products to rise. Leavening affects crumb structure, crust, aroma, and texture. The term covers both biological leaveners, such as yeast and sourdough cultures, and chemical leaveners, such as baking powder and baking soda.

Biological leaveners include baker's yeast (Saccharomyces cerevisiae), which ferments sugars to carbon dioxide and alcohol, and sourdough cultures, a mixture of wild yeasts and lactic acid bacteria. Yeast leavens dough relatively quickly, while sourdough provides a slower fermentation, enhanced flavor, and acidity that influences dough strength and shelf life.

Chemical leaveners generate carbon dioxide through acid–base reactions. Baking powder releases gas upon hydration and heat; baking soda requires an acid such as dairy, yogurt, or vinegar to activate it. These leaveners are common in cakes, pancakes, muffins, and other quick breads, and they do not rely on microbial fermentation.

Handling and storage vary by type. Yeast should be stored cool and dry; dry yeast keeps longer than fresh yeast, which requires refrigeration. Sourdough starters are maintained with regular feedings. Chemical leaveners have a long shelf life if kept dry and in a sealed container, but they lose potency over time, especially after the best-before date.

Historically, leavening began with natural fermentation in ancient breadmaking. The development of commercial yeast in the 19th century enabled standardized baking and broader distribution of leavened products. Today, a range of leavening agents is chosen to suit dough hydration, flavor, texture, and production scale.