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


Word it out food scienceCaramel

Caramel is made by heating sugar until it turns brown. It is used as a flavouring or colouring for food and drink.


The science bit

Caramelisation is the process of cooking sugar until it turns brown.

If you cook the sugar too much it burns, blackens and breaks down to carbon.

Sugar used in cooking is called sucrose. When you heat sugar, water is removed and the sugar melts. As the sugar cooks it turns from sucrose to glucose and fructose.

Caramelisation starts at very high temperatures so you must not touch or taste until the food is cool.

Sugars in foods all caramelise.

Fructose is a sugar found in honey and fruits and it caramelises at low temperatures, so if you bake products such as cakes with honey, they cook to a darker colour.

Flour sugar is called maltose.


How is it used in food products?

Caramel is used in food and drink products to give a brown colour and creamy, sweet flavour and is labelled E150.

Caramel is the most widely used food colouring. It is made by heating sugar beet or sugar cane.

It is used in ice cream, biscuits, soya sauce, caramel sauce, gravy browning, cola, dessert mixes like Angel Delight.

Allergen alert – caramel can be made from wheat, barley and milk so people with allergies must check the ingredient list.


Make some caramel

You need

A non stick pan, 50 g white sugar, wooden spoon

Making caramel is dangerous as it reaches a very high heat.

Put the sugar in the dry pan and place in the heat.

Let the sugar dissolve and gradually turn dark brown. Swirl the pan – try not to use a spoon as a metal spoon will get very hot.

Do not taste or dip your fingers in it! If hot caramel contacts your skin, run under the cold tap.

To make a praline, can add nuts such as almonds and walnuts to the sugar then pour onto a greased baking sheet, spread and leave to cool for about 1 hour.

Break into pieces or bash with a rolling pin.

What can I cook?

Caramel is used to make sweet dishes such as creme caramel which is a creamy custard cooked on top of a layer of caramel.

Creme caramel

Makes 2


50 g sugar

2 tbs water


2 eggs

10 g caster sugar – 2 tsp

vanilla extract

200 ml whole milk


Heat the oven to 150C/Gas2. You need to ramekin dishes or oven proof tea cup  to cook the custard in.

Make the caramel by heating the sugar and water in a saucepan to dissolve the sugar, stirring until the sugar dissolves. Boil without stirring until the sugar turns dark brown.

Pour the caramel into each of the ramekin dishes and leave to cool.

Whisk the eggs, sugar and vanilla extract with a whisk until smooth. Beat in the milk.

Stain into a measuring jug then pour into each of the ramekins.

Put the ramekins in a roasting tin which is half filled with boiling water.

Cook for 20-30 minutes in the oven until the custard is set.

Cool before serving. Chill in the fridge if possible.

To serve loosen the edges of the custard, cover with a plate and tip out the custard onto the plate with the caramel topping.


Oranges in caramel – serves 4

Slices of orange soaked in caramel sauce – delicious with Greek yogurt.


2 large oranges

100 g sugar

100 ml water


Prepare the oranges by cutting off the peel with a sharp knife.

Slice each orange into very thin rounds and put in a dish along with any of the juice.

To make the caramel, heat the sugar and water in a large saucepan and swirl around to dissolve the sugar. Bring to the boil without stirring and let the syrup become a dark gold colour.

Add the oranges to the pan and stir very quickly to absorb the caramel. If you take too long the caramel will stick to the pan. Tip the oranges onto a flat plate and leave to cool.

Take care not to touch or taste the caramel as it reaches a very high temperature!


Did you know

The lady owner of a grocery shop in Seaford, Sussex made up jars of caramel syrup by heating sugar until golden brown and then adding water. She sold it to customers to use in gravies and puddings.


To do

Use the internet to find 10 products which have caramel as one of their ingredients. In each case explain why it is used.

Why do I need to know the science of caramelisation?

Cooking cakes – the ingredients

Cooking cakes – ingredients matter

What happens if I leave things out?

In this experiment you make a batch of small sponge cakes.

Each time you leave one ingredient out and see what happens.

Why do I need to do that?

If you leave an ingredient out, the look and the taste of the cake changes.

This picture shows sponge cake with no egg, no fat, no baking powder

Cakes with ingredients missing

What to do

Make 4-5 batches of sponge cakes – each batch has an ingredient missing.

Sponge cake basic recipe – makes 6 cakes

60 g margarine
60 g caster sugar
1 egg, beaten
60 g plain flour
1 level teaspoon baking powder
Preheat the oven to 180C.
Beat the margarine and sugar together until creamy.
Beat in the egg and stir in the sieved flour and baking powder until smooth.
Spoon equal amounts into 6 baking cases and bake for 20 -25 minutes until firm and golden.
Cool on a wire rack.

Leave out the egg
Follow the basic recipe but replace the egg with 60 ml (60g) water.
Share into 6 baking cases and bake in the same way.

cake no egg

Leave out the fat – margarine
Mix together the sugar, flour, baking powder and egg to a batter.

Spoon into 6 baking cases and bake in the same way.

cake no fat

Leave out the baking powder
Make the same as the basic recipe but don’t add the baking powder.

Share into 6 baking cases and bake in the same way.

Leave out the sugar
Mix the margarine, flour and baking powder together.
Share into 6 baking cases and bake in the same way.

Use the chart to compare results

Cake Flavour Texture
Basic recipe Buttery, sweet, delicious Spongy with air bubbles and well risen
No egg Sweet and buttery but difficult to eat Dough collapses in middle and is stringy
No fat Dry and sweet but not delicious Spongy and light, but tough
No baking powder Sweet and firm, buttery Firm and rather hard
No sugar No sweetness or butteriness Hard and chewy

What does each ingredient do?
Work it out from the change in flavour and texture of the cakes.

Ingredient in cake What does it do?
Margarine – fat
Baking powder

Of course I didn’t try and cook a cake without flour!