Why we cook foods
Methods of cooking
Cooking proteins
Raising agents
Why do we cook foods?
We cook foods for a number of reasons. Some of them are:
•To kill harmful microbes that may cause food poisoning
•To make the food easier to digest
•To improve the flavour of the food
•To improve the texture of the food
How can we cook foods?
There are several ways to cook foods.
Baking and roasting
In an oven. Hot air
surrounds the food
Cakes, meat
Boiling
In boiling water.
Vegetables can lose
vitamins
Eggs, potatoes
Steaming
In steam above water.
Maintains vitamins.
Vegetables, fish
Frying
In hot oil
Chips, eggs
Grilling
Under a grill. Food is
heated by direct
radiation
Steak
Microwaving
Uses waves to cook the
food
Fish, ready meals
Cooking Proteins
Eggs are a good source of proteins. We know it is a chemical
change because the appearance changes.
When you heat up proteins, the molecule changes shape. We say
is has been denatured.
Raising Agents
When we make a cake it is important it rises. We add a raising
agent.
Baking powder is a raising agent which contains sodium hydrogen
carbonate.
When it is heated it decomposes (breaks down)
Sodium Hydrogen  Sodium
Carbonate
2 NaHCO3
+ Water + Carbon
Carbonate
 Na2CO3
Dioxide
+ H2O
+ CO2