C1A REVISION NOTES

Cooking

We eat some foods raw, like fruit, nuts and salad
vegetables
Others have to be cooked

We cook food for different reasons

Improves taste and flavour ­ Meat and Potatoes
Easier to digest ­ Potatoes and Eggs
Removes toxins ­ Kidney beans
Kills bacteria ­ Eggs and Chickens
Improves texture ­ Eggs and Potatoes




Methods of cooking

Methods Advantages Disadvantages
of
cooking
Baking Dry high temperature…

lost in the
water
Food can be
` mushy '
Frying Placing in very hot fat Crisp outside High fat
or oil Fast content can
( ~ 200 °C ) Tasty cause weight
increase and
heart
problems
Steaming Placing food in Food keeps taste Not suitable
steamer above boiling and…

Proteins

Good sources of proteins are :

Meat
Fish
Cheeses
Eggs
Nuts

When proteins are heated they denature ( change shape )
The process that causes protein molecules in eggs and
meat to change shape during cooking is irreversible and is
called denaturing

This causes egg white to become solid and opaque




Starch

Starch is a complex carbohydrate

Food supply in carbohydrate is :

Potatoes
Rice
Pasta
Bread
Kus ­ kus

Cooking any plant material softens the cell walls and makes
the food more easily digestible

Cakes and bread

When you bake a cake you add baking powder to make it
rise
Chemically speaking baking powder is Sodium hydrogen
carbonate
When it is heated it produces carbon dioxide gas which
gets trapped in the cake making it spongy

Sodium hydrogen carbonate Sodium carbonate + Carbon
dioxide…

The limewater turns milky showing that carbon dioxide was
given off