Food Science – Chemical Raising agents NEA 1

Raising agents

Four main raising agents are used in cooking:

  1. Air – egg whites, beating creaming, rubbing in
  2. Steam – profiteroles,choux pastry, Yorkshire pudding
  3. Carbon dioxide – yeast fermentation, baking powder, self raising flour
  4. Chemicals – bicarbonate of soda, baking powder

How do chemical raising agents work?

There are 3 main chemical raising agents:

  1. Sodium bicarbonate (bicarbonate of soda, E500 sodium carbonates) is a raising agent used in soda bread and gingerbread. It is an alkali.
  2. Cream of tartar is an acid called potassium hydrogen tartrate and it is mixed with bicarbonate of soda to provide the acid ingredient for baking powder. This ingredient can be added to stabilise whipped egg whites and increase their volume, and is added to whipped cream.
  3. Baking powder is made from the alkali, bicarbonate of soda and the acid, cream of tartar.  As soon as liquid is added to the baking powder or bicarbonate of soda, carbon dioxide gas bubbles are given off which push up the cake, muffin or bread mixture. Baking powder has a drying agent mixed with it to stop it reacting in the packet.

Make your own baking powder:  Mix 1 level teaspoon bicarbonate of soda and 2 level teaspoons cream of tartar.

Self raising flour is made from plain flour and baking powder.

Make your own self raising flour:  Add 1 heaped teaspoon baking powder to 100 g plain flour.

The science bit

Bicarbonate of soda produces more carbon dioxide gas if it is mixed with an acid food – cream of tartar, buttermilk, sour milk. If you don’t mix it with an acid, you get a soapy taste in the food.

Baking powder experiment

Experiment to blow up balloons.

You need

Bicarbonate of soda

Baking powder

Cream of tartar

3 small DRY 500ml plastic water bottles

3 balloons


  1. Label the bottles 1,2,3.
  2. In 1 put 2 heaped teaspoons of bicarbonate of soda
  3. In 2 put 2 heaped teaspoons of baking powder
  4. In 3 put 2 level teaspoons of cream of tartar and 1 level teaspoon of bicarbonate of soda.
  5. Boil a kettle of water. Mix 300ml boiling water with 200 ml cold water.
  6. Pour 100ml of hot water into 1, quickly put a balloon on top and shake.
  7. Pour 100ml of hot water into 2, quickly put a balloon on top and shake.
  8. Pour 100ml of hot water into 3, quickly put a balloon on top and shake.
  9. Watch what happens. Which balloon is blown up the most?

Which one does not blow up?

Explain why the balloons either blow up or remain empty.

For science experiment make some scones

What can I cook?

Irish soda bread

Serves 4


80g self-raising flour

80g plain flour

½ level tsp salt

½ level tsp bicarbonate of soda

100ml buttermilk or 100ml milk mixed with ½ teaspoon cream of tartar or vinegar

soda bread


  1. Preheat the oven to 200C/Gas 6. Lightly flour a baking sheet.
  2. Put the flours, salt and bicarbonate of soda in a mixing bowl and stir.
  3. Make a dent in the centre of the flour and pour in the buttermilk, or milk mixed with cream of tartar or vinegar. Mix quickly to form a soft dough.
  4. Add less or more milk if the dough is not sticky enough.
  5. Turn the dough onto a floured surface and knead.
  6. Shape into a round and flatten the dough slightly before placing on the baking sheet.

Cut a cross on the top and bake for about 25 – 30 minutes or until the loaf sounds hollow when tapped. Cool on a wire rack.

What can I cook?

Cheese and onion muffins

Makes 6

You need

75g margarine or butter

1 small onion (50g), very finely chopped

1 egg, beaten

150 g grated Cheddar cheese

100 g self raising flour

1 level teaspoon baking powder (2g)

2 tbs milk (30g)

Nutrition per portion

Energy 273 kcal, Protein 9.4g, Sugar 1 g, Fat 20g, Salt 0.9g

Allergens gluten, milk, egg


Preheat the oven to 200°C/Gas 6.

Melt the margarine or butter and stir in the chopped onion, beaten egg, 120g cheese – reserve the rest for the top.

Mix in the flour and baking powder to make a soft dough and add milk to soften the dough.

Place equal amounts into 6 muffin cases and bake 20-25 minutes until they are golden brown and spring back to touch.


Mixing bowl, muffin tray, teaspoon, measuring jug, chopping board, sharp knife, fork, grater, muffin cases

Presenting results

I used The Nutrition Program to present the results of the tasting. This is how it is done.

Click My Recipes and name one as Scones with different raising agents

Put in the scone recipe in Ingredients. You can test out different scone recipes using plain flour, self raising flour, flour with bicarbonate of soda and flour with baking powder.

Go to Star Profile.

Star profile for chemical raising agents

For each Taster put in the name of the raising agents – I’ve chosen plain + baking powder, SR + baking powder, plain + bicarb and tartar, SR flour

Then think of Descriptors for sensory appraisal – your tasting work.

I’ve chosen light, well risen, crumbly, solid

Then tasted the scones and given each a mark out of 5 where 0= not and 5= very.

This is a new function added for NEA 1 test – Click Hide Rating.

Star profile for chemical raising agents

I can now see the Star Profile with each scone tasted.

Then I can write my Evaluations.

Evaluation of raising agents

Then Download as JPG.

Full marks I hope!!

In the book Food Science You Can Eat

NEA 1 Food Investigations 10 Tasks  – Task 1 – Starchy ingredients to thicken sauces and soups  
Task 2  – Chemical raising agents for scones, cakes and biscuits 
Task 3  – Fats used in shortcrust pastry. 
Task 4  – Flours used in pastry – use for gluten tests 
Task 5  – Gluten in flour for breadmaking
Task 6 – Gluten in flour for pasta making
Task 7  – Sponge cakes – changing the flour
Task 8  – Sponge cakes  – changing the sugar
Task 9  – Eggs as setting agents 
Task 10  – Egg foams and meringues