Food Science

Question 1

Gelatinisation

Answer 1

• when flour is mixed with a liquid and heated
• the starch grains cannot dissolve in the liquid
• as heat is applied the starch grains swell and break open to thicken the mixture

Question 2

Dextrinsation

Answer 2

When dry heat is applied to flour products, the crust goes brown
(Starch in flour changes to dextrin)

Question 3

Caramelisation

Answer 3

When sugar starts to change colour after being heated

Question 4

Mallard reaction

Answer 4

Occurs in biscuits when they contain carbs and protein

Question 5

Shortening

Answer 5

• when fat is used in rubbed-in mixtures, the product will have a crumbly texture
• this happens because the fat coats the flour to give it a waterproof coating which prevents gluten from developing

Question 6

Aeration

Answer 6

• the process of trapping air in a mixture to cause it to rise
• this happens because when a fat and sugar are creamed together, air is trapped, so when the product is heated the air expands helping the mixture to rise

Question 7

Plasticity

Answer 7

• the ability of a solid fat to soften over a range of temperatures
• some products are designed to have a lower melting point -> like butter that can spread straight from the fridge

Question 8

Emulsification

Answer 8

• process of using an emulsifier to prevent a mixture of oil and liquid from separating
• this happen because emulsifiers attract oil and liquid and hold them together
• egg yolk has lecithin which holds oil and liquid together

Question 9

What happens to protein foods under heat

Answer 9

Meat
- coagulates then the fibres shrink and juice is squeezed out

Fish
- muscles in the fish shrink as they are only short
- if it is cooked for too long the fibres become tough

Eggs
- egg white coagulates and changes from opaque to white colour then the yolk coagulates
- if eggs are heated too quickly the liquid from the egg separates out and the protein gets tough (syneresis)

Milk
- when milk is heated a skin forms on top -> this is the protein coagulating

Cheese
- the protein coagulates

Question 10

Foam formation

Answer 10

• a foam is produced when eggs are whisked
• when eggs are whisked, they produce a mixture of gas and liquid
• the gas produced is spread throughout the liquid and foam is produced

Question 11

Aeration with eggs

Answer 11

• when egg whites are whisked the protein albumin is stretched and traps air

Question 12

Gluten

Answer 12

• names of the proteins found in wheat which form gluten are gliadin and glutenin
• gluten is developed in bread when it is kneaded
• soft flours are used in cakes as it has a low gluten content so cakes are soft

Question 13

Acids

Answer 13

Used to change the shape and structure of protein foods

Question 14

Enzymic browning

Answer 14

When foods go brown after being cut as they react with oxygen

Question 15

Setting up a tasting panel

Answer 15

1. Set up a quiet area where people won’t be disturbed
2. Give the testers a piece of apple to clear the palate
3. Use small quantities of food on plain same sized plates
4. Don’t give too many samples at once
5. Serve food at the right temp for the product
6. Use clean untensils each time
7. Use codes for the products, not the name
8. Have any charts ready before
9. Make sure the testers know how to fill in the charts