Raising agents

• What is the definition of a raising agent?

  An ingredient or process that introduces a gas into a mixture so that it rises when cooked
• Why are raising agents used?

  . Consumers expect baked products such as bread, cakes and scones to have a light, open, soft and ‘spongy’ texture

  . To create the desired texture, a raising agent is added to the uncooked mixture to introduce lots of gas bubbles, which will expand when the mixture is baked in the oven
• What is a raising agent?

  A substance that produces gas bubbles
• What gases are produced by raising agents?

  Air, carbon dioxide, and steam
• How is air trapped in a mixture?

  By creaming, rubbing-in, beating, whisking, or folding
• What gas is produced by yeast in bread?

  Carbon dioxide (CO2)
• What role does bicarbonate of soda play in baking?

  It produces carbon dioxide gas in mixtures
• What is baking powder made of?

  Bicarbonate of soda and an acid
• How is steam introduced into mixtures?

  By adding moisture that turns to steam
• What are the three ways gases are introduced into mixtures?

  1. Chemical: using baking powder or bicarbonate of soda
  2. Mechanical: whisking, beating, sieving, creaming, rubbing in, folding, or adding moisture
  3. Biological: using yeast
• How does mechanical introduction of gas differ from chemical introduction?

  Mechanical involves physical actions, chemical involves reactions
• What is the purpose of self-raising flour?

  It contains baking powder for leavening
• What is steam in the context of raising agents?

  Water in a gaseous state
• How do raising agents work?

  . The action of moisture, heat or acidity (or a combination of all three) triggers a reaction with the raising agents to produce the gas bubbles

  . As a cake mixture, batter or dough cooks, the gas bubbles given off by the raising agent make it rise by expanding and pushing it upwards and outwards

  . The gas bubbles then become set in and provide the soft, sponge-like texture
• What is the process called when fat and sugar are mixed to trap air bubbles?

  Creaming
• How do air bubbles get trapped in a mixture during the creaming process?

  By mixing fat and sugar with a wooden spoon
• What surrounds each air bubble during the creaming process?

  A thin layer of fat
• What happens to the color of the mixture during the creaming process?

  It becomes lighter
• What role does egg play in the mixture after creaming?

  It coagulates and forms a wall around air bubbles
• What happens to the air bubbles when the mixture sets?

  They expand and raise the mixture
• What causes the mixture to set during baking?

  Egg proteins coagulate and starch granules expand
• What is the effect of rolling and folding dough in flaky and puff pastry?

  It traps air in the dough
• What is the result of the trapped air bubbles expanding during baking?

  Light, crisp, and thin layers of pastry
• What happens to the fat between the layers of dough during baking?

  It melts, leaving space filled with steam
• What acts as a raising agent in flaky and puff pastry?

  Steam from water and fat
• What gas is produced by bicarbonate of soda and yeast?

  Carbon dioxide (CO2)
• What is the role of bicarbonate of soda in baking?

  It acts as a raising agent.
• What happens when bicarbonate of soda is heated?

  It produces CO2 gas.
• How do CO2 gas bubbles affect a mixture?

  They help the mixture to rise.
• What would happen if bicarbonate of soda is used alone in baking?

  It would produce an unpleasant taste.
• What is the reaction when bicarbonate of soda is heated?

  Bicarbonate of soda + heat → washing soda + CO2 + water
• What is the purpose of mixing bicarbonate of soda with cream of tartar?

  To prevent the formation of washing soda.
• What is produced when bicarbonate of soda is mixed with cream of tartar and heated?

  Sodium potassium tartrate, CO2, and water
• What is baking powder made from?

  Bicarbonate of soda and cream of tartar
• What is self-raising flour made from?

  Plain flour and baking powder
• When is bicarbonate of soda used alone in baking?

  In strong tasting mixtures like gingerbread.
• What type of organism is yeast?

  A microscopic, single-celled fungus
• What conditions are needed for yeast to produce CO2 gas?

  Warmth, moisture, food, and time
• What is the process called when yeast produces CO2 gas and alcohol?

  Fermentation
• How does CO2 gas affect bread dough?

  It makes the dough expand and rise.