eggs

Question 1

role

Answer 1

expand and capture air during baking & therefore increase the volume during baking

help to bind ingredients during mixing

set during baking to form a firm structure

contribute to the rich texture of foods

coagulate and set when heated

Question 2

types

Answer 2

HEN - Most common and versatile

QUAIL - Approx. a third the size of hen’s eggs and the shell is green-fawn with dark spots. They are relatively expensive and are mainly used for garnishes or high quality meals.

DUCK - larger than hen’s eggs and have a stronger taste. They must be well cooked as they are more susceptible to bacterial contamination.

Question 3

storage

Answer 3

*pointed end downwards - eggs should be stored pointed end down to keep the yolk centered and keep any bacteria as far as possible from the yolk (which is far more likely to be contaminated by any bacteria that enters the egg than the non-bacteria friendly white).

*in cardboard carton – allows exchange of gases but minimises absorption of other food odours

*last longest at 4oC (fridge)

*return eggs to room temperature before use in recipes

Question 4

composition

Answer 4

Approximately (by weight):
*10% shell
*60% white (albumen)
*30% yolk

*view photo

Question 5

water test for freshness

Answer 5

Place egg (in shell) in a bowl of water – a fresh egg sinks to the bottom (less gases in air space so the egg is more dense), whereas a stale egg rises (more gas so egg is less dense & floats).

Question 6

test for freshness

Answer 6

2 ‘use by date’ – a useful guide if eggs have been stored properly

3 The Haupt Test shows the firmness of the yolk and white - break and gently and place upright on a plate.
* A fresh egg has a high profile (yolk and inner albumen) and covers a small area (doesn’t spread much)
*A stale egg has a flat yolk and a thin while that spreads out to cover a large area

Question 7

function - foaming agent

Answer 7

Example : in sponge cakes & soufflés.
Egg white, when beaten, gently increases volume by trapping and holding air. The air is trapped in bubbles surrounded by a thin elastic film of egg white.
On heating the air expands and the protein in the egg white coagulates, trapping the air.

Question 8

function - emulsifying agent

Answer 8

Example : hollandaise sauce, mayonnaise, aioli
The egg yolk proteins coat the oil droplets, creating an emulsion.
This prevents the ingredients from separating, maintaining them as a smooth mixture.

Question 9

Function - thickening agent

Answer 9

Example : in custards, quiches, sauces.
When heated, eggs proteins coagulate or thicken.
Egg proteins have the ability to attract and hold large quantities of liquids, thus forming a gel.
Egg white thickens at approx. 60oC and egg yolk solidifies at around 68oC, beaten mixture coagulates at approx. 65oC.
If heating is continued beyond this temperature, the white becomes tough and shrinks and the yolk becomes dry and crumbly. This over-coagulation causes curdling in food productions.