C1f - Cooking and food additives

Question 1

What happens to the egg and meat when they are cooked(2)

Answer 1

heat energy from cooking breaks some of the chemical bonds in the protein, causing shape of protein molecules to
irreversibly change shape(denature)

permanent shape change of the protein molecules causes texture and appearance of egg/meat to change; more edible texture

Question 2

Explain why potato is easier to digest if it is cooked(3)

Answer 2

cell walls (made of indigestible cellulose) rupture, resulting in loss of rigid structure & softer texture

starch grains absorb water, swell up and spread out

easier to digest than raw potatoes

Question 3

Thermal decomposition of sodium hydrogencarbonate word equation

Answer 3

sodium hydrogencarbonate –> sodium carbonate + carbon dioxide + water

Question 4

Thermal decomposition of sodium hydrogencarbonate balanced symbol equation

Answer 4

2NaHCO3 - Na2Co3 + CO2 +H2O

Question 5

What is baking powder and why is it used(2)

Answer 5

Baking powder is sodium hydrogencarbonate

Decomposes to give carbon dioxide, which expands when heated to help cakes rise

Question 6

Describe emulsifiers

Answer 6

molecules that have a water loving (hydrophilic) part and an oil or fat loving (hydrophobic) part

Question 7

How does an emulsifier help keep oil and water from separating? (3)

Answer 7

hydrophilic end bonds to water molecules

hydrophobic end bonds with oil/fat molecules

hydrophilic end is attracted to the water molecules which surround the oil, keeping them together