Functional Properties of Food

Question 1

Egg - aeration

Answer 1

• When egg white is beaten it traps air due to the protein in the egg stretching and trapping air bubbles in a honeycomb like mesh and forms a foam making sponges lighter
• eggs give a better volume when whisked at room temp
• if egg not whisked enough foam will not have good volume
• if egg overbeaten the protein in egg is overstretched and will collapse
• meringues, swiss rolls

Question 2

Egg- emulsifying

Answer 2

• egg yolk contains a substance which acts as an emulsifier meaning it will prevent oil and other liquids from separating
• egg yolk forms an emulsion with butter and liquid from eggs prevents curdling
• egg should be room temp and added gradually
• mayonnaise, cake making

Question 3

Egg- coagulation

Answer 3

• when eggs are heated they change from a fluid to a more solid state
• coagulation thickens fillings and quiches eg, when eggs are mixed into a liquid like milk then heated it will set the egg then thicken
• if egg protein heated for too long or at a high temp then a hard and tough mass as protein shrink and liquid pushed out
• egg custard, quiche

Question 4

Egg - binding

Answer 4

• the egg protein coagulates when heated and bind or hold combination of ingredients together “food glue”
• hamburger

Question 5

Egg - glazing

Answer 5

Eggs can give a golden brown coloured glaze and add more flavour to products
eg scones and pastry

Question 6

Flour - gelatinisation

Answer 6

• In sauce making when starch and water is heated, the water is absorbed through the walls of starch granules which then swell and burst which thickens the liquid and allow sauce to set when cooled
• sauces and soups

Question 7

Flour - dextrinization

Answer 7

• the surface starch in scones or pastry or cakes change to dextrin during cooking due to dry heat in oven, helps baked goods to become golden brown
• toast, cake

Question 8

Sugar - caramelisation

Answer 8

• sugar helps to colour products such as the tops of cakes by caramelising in dry heat of oven
• when sugar is heated in a liquid or as a topping it begins to caramelise and brown
• cakes, toffee

Question 9

Sugar - aeration and flavour

Answer 9

aeration - sugar also traps air when creamed with fat making the end result lighter in texture
flavour - sugar makes food sweeter
eg cake making and biscuits

Question 10

Fat - creaming

Answer 10

• fat and caster sugar are creamed together until they form foam which traps air in the mixture in tiny bubbles which make mixture lighter and help cakes to rise
• cakes and biscuits

Question 11

Aeration - rubbing in

Answer 11

• fat is rubbed into the flour and coats the flour particles, the mixture looks like breadcrumbs. this forms a waterproof barrier but also traps air as the mixture is lifted and rubbed in with fingertips
• pastry, cakes