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Raising Agents

Raising Agents . To understand what they are To learn what the difference between a chemical raising agent and a mechanical raising agent is. . What are raising agents? . Used in most recipes for: Cakes Bread Pastries Desserts They give products a light, spongy or flaky texture.

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Raising Agents

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  1. Raising Agents To understand what they are To learn what the difference between a chemical raising agent and a mechanical raising agent is.

  2. What are raising agents? • Used in most recipes for: • Cakes • Bread • Pastries • Desserts • They give products a light, spongy or flaky texture. • Inorder for them to be like this their mixtures have to be raised during baking.

  3. How do they work? • Used to put gas into a mixture. • Gases expand when they are heated and they can cause the mixture to rise. • They can also be known as leavening agents. (means to lift up) • Gases used are: • Carbon dioxide (co2) • Air (mixture of gases) • Steam (water as a gas)

  4. As the mixture cooks, the expanded gas bubbles become set inside it and this gives the baked mixture a soft, spongy and light texture. • There are two types of raising agents.

  5. Baking powder Bi carbonate of soda Yeast Sieving Creaming Whisking Folding and rolling Rubbing in Chemical Mechanical

  6. Baking Powder • This is a mixture of two chemicals (an alkali and an acid) which react when there is moisture and heat. • Bicarbonate of soda + cream of tar tar = carbon dioxide gas bubbles • Added to plain flour to make self raising flour • List 5 products that are made using baking powder.

  7. Bicarbonate of soda • Known as baking soda • Produces carbon dioxide when there is moisture and heat • Can only be used in strong flavoured dishes like chocolate cakes or gingerbreads. • Leaves a soapy flavour • Can add an acidic flavour like lemon juice or buttermilk and a soapy flavour does not occur.

  8. Yeast • A tiny, single celled plant that you can only see under a microscope. When it has moisture and warmth and food (sugar or starch), it breaks down the food into CO2 and alcohol. • Known as fermentation. • Gas bubbles make the dough stretchy rise when left in a warm place for an hour. • The alcohol evaporates when bread is baked. • What types of products use yeast?

  9. Mechanical Raising agents • Air is a mixture of gases and it can be added to products in various ways. • Sieving: traps air between flour particles • Creaming: (butter and sugar) traps tiny air bubbles which expand and make the cake rise. The egg will prevent the bubbles from escaping as it sets around them.

  10. Whisking: egg whites (or with sugar). Traps a large amounts of bubbles as the air is trapped in the egg protein. • Folding: layers of air are trapped. During baking the fat melts and leaves a space that is filled with steam from the water. It also lifts the mixture. • Rubbing (fat and flour): traps some air in the mixture • For each method try to give an example of the dish the method would be used in.

  11. Experiments • Completely fill a glass full of flour. Sieve the flour and see if you can get the flour back in the glass • Dissolve 1tsp of fresh yeast into 100ml of warm water and t tsp of sugar. Leave in a warm place for 10 minutes. What happens?

  12. Activity • Name 3 chemical raising agents • Name 3 mechanical raising agents • Describe 2 ways that air can be added to mixtures • Write a recipe for fairy cakes. List all the ways the air is added to help makes the cakes rise. • Name the raising agent that is used when making bread. • Answer the questions on page 189 to recap on what you have learnt.

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