Cooking food and additives
Cooking brings about chemical changes in food.The texture and taste changes when food is cooked.
Food additives are included in food to improve their shelf-life, appearance and flavour. Antioxidants such as ascorbic acid prevent food from going off by reacting with oxygen.
Cooking and chemical changes
Cooking involves chemical changes:
- new substances are made
- the process is irreversible
- an energy change occurs.
For example, bread turns brown as it is toasted. Sugars in the bread break down to form carbon. This change needs heat energy from the toaster, and it cannot be reversed.
Meat and eggs are good sources of protein.The protein molecules change shape as a result of the heat energy they absorb. This is called denaturing and it is permanent. Denaturing causes changes in the appearance and texture of the meat and eggs when they are cooked. For example:
- meat becomes firmer and turns from red to brown
- egg white solidifies and becomes white instead of transparent.
Potatoes are a good source of carbohydrate, mainly as a complex carbohydrate called starch. Raw potato is hard and has an unpleasant taste but it becomes softer and easier to digest when is cooked. This is beacuse:
- the cell walls break, leading to a softer texture
- the starch grains in the cells swell and spread out.
Everything in food is made from chemicals. Some of these are natural, and some are artificial. Processed foods, including vegetable oils, may have chemicals added to them. These additives have different roles, including extending a product’s shelf-life and improving its taste and appearance.
Types of food additives
type of additivereason for adding it antioxidants stop food from reacting with oxygen
improve the colour of food
improve the flavour of food
help oil and water mix, and not separate out