Home Economics Homework
Name: _____________________________________
Year 8
Date: _________________
Raising Agents
Learning objective
By the end of this lesson, you should be able to:
 define the meaning of the term raising agent;
 identify the types of raising agents used in food.
Keywords: raising agent, texture, carbon dioxide.
In order to make mixtures rise and have a light texture, a raising agent must be introduced. There are three
types of raising agents: mechanical, chemical and biological.
Mechanical
This is the incorporation of air into food products by using different techniques.
 sieving
 rubbing in fat
 whisking / beating
 rolling / folding
 creaming fat and sugar
Can you think of any examples of food products that would use these methods? __________________________
Chemical
This is the addition of a chemical, such as bicarbonate of soda, baking powder
or self-raising flour. When a liquid is added to the chemical raising agent, it
produces bubbles of CO2 gas. In a hot oven the CO2 gas expands and pushes
up the mixture. Some of the gas escapes and some is trapped in the mixture as
it cooks and sets. Cakes use a combination of chemical and mechanical raising
agents.
Biological
CO2 gas may also be produced in flour mixtures by the biological action known
as fermentation which is brought about by yeast combining with the sugar in
flour in moist, warm conditions.
Yeast grows and ferments. Yeast is a single-celled plant fungus, which needs
food, warmth and liquid to ferment. Most types of bread are made with yeast.
The yeast uses the flour for food, and ferments with the warm liquid to produce
carbon dioxide. The dough increases in size during the process called ‘proving’
when the dough is left in a warm place, which encourages the yeast to grow.
When the bread is baked, the carbon dioxide gas expands, pushing up the
dough. The yeast is killed by the heat and the bread dough cooks and sets.
Questions
1) In your own words, explain what a raising agent does to food. (ie. What do raising agents do to the texture of
food?) Give an example to support your answer.
2) How do raising agents work? (In your answer use the words reaction, moisture, carbon dioxide.)
Home Economics Homework
Name: _____________________________________
Year 8
Date: _________________
Home Economics Homework
Name: _____________________________________
Year 8
Date: _________________