Booklet 2 Food Science

Question 1

Conduction

Answer 1

The movement of heat from one item to another through direct contact e.g. flame of a gas ring touches the bottom of a pan, heat is conducted to the pan.

Question 2

Convection

Answer 2

The transfer of heat through a fluid, which may be liquid or gas

Question 3

Radiation

Answer 3

Does not require physical contact between the heat source and the food being cooked. Energy is transferred by waves of heat or light striking the food.

Question 4

Coagulation

Answer 4

Proteins coagulate (set) when heated in dry or moist methods, if overheated they may become tough and difficult to digest.

Question 5

Colloidal structure

Answer 5

Formed when one substance is dispersed through another, but does not combine to form a solution. Gels, sols, foams (e.g. egg white foam) and emulsions (e.g. butter) are all types of colloids.

Question 6

Emulsion

Answer 6

A mixture of oil and water, usually with an emulsifier to prevent separation. Can be oil in water (milk) or water in oil (butter).

Question 7

Gelatinisation

Answer 7

When heat is applied, (starch forms a suspension, it swells at 60°C, breaks open and thickens the mixture at 80°C, full gelatinisation complete at 100°C)

Question 8

Viscosity

Answer 8

The thickness of a liquid

Question 9

Shortening

Answer 9

When rubbed in, fat coats grains of flour, giving a waterproof coating, preventing the gluten developing, so the product is short and crumbly e.g. pastry.

Question 10

Plasticity

Answer 10

The ability to be shaped and spread with light pressure due to melting temperatures. (E.g. butter is very hard and difficult to spread straight out of the fridge, has low plasticity.) (E.g. vegetable spread is soft straight out of the fridge, has high plasticity.)

Question 11

Aeration

Answer 11

Adding pockets of air to something. When butter is creamed with sugar, air is trapped which expands

Question 12

Caramelisation

Answer 12

In moist heat sugar will melt/dissolve. At 154° sugar stars to change colour (caramelise). Longer it is heated the darker the caramel.

Question 13

Maillard reaction

Answer 13

Sugar will caramelise in dry heat. When mixed with proteins (e.g. eggs, flour) it causes browning.

Question 14

Dextrinisation

Answer 14

The process of starch molecules breaking down into smaller molecules when starchy foods are exposed to dry heat

Question 15

Denaturation

Answer 15

When protein foods are heated, whisked in or have acid applied, the chemical structure changes.

Question 16

Albumin

Answer 16

At type of protein made in your liver

Question 17

Syneresis

Answer 17

The sudden release of moisture contained within protein molecules, usually caused by excessive heat.

Question 18

Gluten

Answer 18

An elastic protein complex. Flour contains the proteins gliadin and glutenin, when water forms gluten. More gluten = more stretchy.

Question 19

Enzymic browning

Answer 19

An oxidation reaction that takes place in some fruit end veg, causing the food to brown e.g. apple

Question 20

Oxidation

Answer 20

The loss of water soluble vitamins when fruits or vegetables are exposed to the air or to heat. E.g. B vitamins, vitamin C.

Question 21

Fermentation

Answer 21

Once the oxygen is used up, the yeast starts to anaerobically respire to produce ethanol and carbon dioxide.