1. Cooking

2. Cooking Most food has to be cooked before it is eaten. Which foods can be eaten raw?

3. Why does food have to be cooked? Have a think. Write down your ideas in the form of a spidergram.

4. to kill microbes to improve the texture to improve the taste Why does food have to be cooked? to make it easier to digest to improve the flavour

5. How can food be cooked? Do you recognise these different ways of cooking? In each case write down the name of the method.

6. The food is cooked using electromagnetic radiation with a wavelength of about 1cm. microwave cooker

7. The food is enclosed in a metal cuboid and is cooked using hot air. oven

8. The food is placed in water at 100ºC boiling

9. The food is placed in hot oil. frying

10. The food is cooked by infra red radiation. grilling

11. The food is cooked by hot water vapour. steaming

12. Cooking is a chemical change • This means... • a new substance is made • it cannot be reversed • an energy change takes place

13. What changes take place when a potato is cooked?

14. Potatoes are a good source of ___________ carbohydrate When heated, the cell walls of the potato cells break down. This makes the potato softer. Enzymes can now get to the starch inside the cell, so the potato is easier to digest.

15. What changes take place when an egg is cooked?

16. Eggs (and meat) are good sources of _______. protein When heated, the molecules in protein change shape. We say the protein has been denatured.

17. Baking powder • Baking powder is used in making cakes. • It contains sodium hydrogencarbonate. • This breaks down (decomposes) when heated and makes carbon dioxide. • Carbon dioxide makes the cake rise.

18. Baking powder This is a chemical change. The word equation is: sodium hydrogen carbonate sodium carbonate carbon dioxide + + water The test for carbon dioxide: Carbon dioxide turns _____ water ______. lime cloudy