Raising agents

Raising agents

Mechanical
1. seiving
  1. Flour is sieved before being added to mixtures to trap air and get rid of lumps
  2. sieving is important in fatless sponges.
2. whisking
  1. meringues are whisked together to make the light airy texture.
3. steam
  1. Steam can also act as a raising agent in puff pastry.
  2. Used as a raising agent in batters like Yorkshire pudding.
  3. it's made when water is heated at a high temperature and adds moisture
  4. The oven is usually very hot.
4. Creaming
  1. Used to make cake
  2. When a fat and sugar are mixed together they trap lots of little air bubbles.
  3. Each bubble is surrounded by a thin layer of fat.
5. Rolling and folding
  1. Mainly used in puff pastry.
  2. works because it traps air bubbles which expand during baking.
  3. Creates thin crisp layers.
Chemical
1. Baking powder
  1. Baking powder is a mixture of bicarb and an acid so there is no soapy flavour
2. self-raising flour
  1. Self-raising flour already has baking powder mixed into it.
3. bicarbonate of soda
  1. Bicarbonate soda is an alkali
  2. It produces washing soda which gives off a soapy flavour.
  3. Bicarbonate of soda is only used by itself with strong tasting mixtures.
    1. Gingerbread
  4. An acid like cram of tartar is used to neutralise the washing powder.
  5. sodium hydrogen carbonate ----> sodium carbonate +carbon dioxide + water
    1. 2NaHCO3 ----> CO2 + H2O + Na2CO3
4. All three chemical raising agents work by releasing carbon dioxide.
5. Used in cakes, scones, and biscuits
Biological
1. Yeast
  1. Yeast is a micro-organism fungus
  2. The gas comes from the yeast respiring.
    1. carbon dioxide
  3. At first the yeast respires aerobically, and then anaerobically
  4. anarobic respiration also releases ethanol which evaporates during baking.
  5. It's mainly used in breads
  6. yeast needs time, moisture, warmth,, and food.
  7. It's called fermentation
  8. The yeast multiplies by a process called budding.
  9. Yeast is destroyed by boiling water and salt.
  10. it's optimum temperature is around 37 C
Raising Agents
1. Raising agents create a light, open texture
2. They create gas bubbles, which expand in the oven.
3. Raising agents make things rise and expand.
4. In the oven the protein coagulates and then sets the mixture allowing the gas to escape
  1. If you take it out too early the protein may not have time to set and the food may collapse.

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