Past Exam Questions Flashcards
In relation to eggs, explain albumin
3
Albumins are a family of proteins
Albumins such as ovalbumin are found in the white of an egg
Albumins give egg white their coagulation properties which can be used thicken sauces such as custard
In relation to eggs, explain lecithin
3
Lecithin is a natural emulsified present in egg yolk
It has the ability to join two immiscible liquids such as oil and water
It has a hydrophilic head and a hydrophobic tail which attach to the water an oil and prevent them from separating to create a permanent emulsion
Describe the dietetic value of eggs
6
Excellent source of HBV protein - growth and repair - important in the diets of vegetarians (meat alternative), children, adolescents and pregnant women
Low in kilocalories - ideal food for calorie-controlled diets
Versatile - suited to many cooking methods and culinary uses - baking, sauces, batters
Inexpensive + cook quickly - minimising energy costs - economical food
High in saturated fats and cholesterol - restricted for those with high cholesterol or CHD (or those at risk) - only eat the whites
Lack carbohydrates and vitamin C - eat with foods high in these
Explain how food labelling on egg cartons is beneficial as a source of consumer information
(8)
Name and address of packer/seller
Egg packaging centre code
Number of eggs in the pack
Class/quality of the eggs e.g. Class A
Date of minimum durability
Rearing method, e.g. free range
Weight, e.g. extra large (XL)/large(L)/medium(M)/small(S)
Storage instructions advising to keep eggs chilled
Name three uses of eggs in food preparation and give an example of each
(3/5)
Whole food - boiled, fried, scrambled eggs
Emulsifier - mayonnaise - oil and water using lecithin
Aeration - eggs trap air when whisked which assist aeration in sponge cakes and meringues
Bind - eggs bind ingredients together and prevent them from falling apart e.g. burgers
Glaze - eggs form a shiny coating of food, giving an attractive finish when baking e.g. scones and pastry
Outline the effects of heat on eggs
9
Proteins coagulate - whites at 60 degrees and yolks at 68 degrees
Eggs whites change from translucent to opaque
Bacteria are destroyed
Some B-group vitamins are lost particularly thiamine (not heat stable)
Eggs curdle if overcooked which causes egg proteins to clump together and squeeze out water, forming lumps of protein and a watery liquid
Eggs become tough and difficult to digest if overcooked
Egg yolk becomes dry and crumbly if overcooked
Egg whites become rubbery if overcooked
A reaction between iron and sulphur causes a green ring to form around the egg yolk if overcooked
What are the properties of eggs
Aeration
Coagulation
Emulsification
Culinary applications of the properties of eggs
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Explain the aeration property of eggs
4
When eggs are whisked their protein chains unfold and air bubbles form
The protein chains entrap air which creates a foam
Whisking creates heat which begins to set albumin which forms a temporary foam
The foam needs to be heated in order to coagulate an set, otherwise it will collapse.
Explain the coagulation property of eggs
4
When eggs are heated their protein chains unfold, straighten and bond together around small pockets of water, causing coagulation
Egg whites coagulate and change from translucent to opaque at 60 degrees
Egg yolks coagulate at 68 degrees
Overcooking causes proteins to clump together and squeeze out water, forming lumps of protein and a watery liquid (this is known as curdling)
Explain the emulsification property of eggs
6
Lecithin is a natural emulsifier present in egg yolk
Lecithin has the ability to join two immiscible liquids (oil and water)
Lecithin has a hydrophilic head and a hydrophobic tail
The hydrophilic head attaches to the water
The hydrophobic tail attaches to oil
Lecithin prevents an oil and a water from separating which creates a permanent emulsion
Give a culinary application of the aeration property of eggs
Aeration - meringues, sponges, soufflés
Give a culinary application of the coagulation property of eggs
Coagulation - binding (beef burgers), thickening (custard, hollandaise sauce), glazing (pastry and scones)
Give a culinary application of the emulsification property of eggs
Emulsification - mayonnaise and vinaigrettes (oil and vinegar), cakes (fat and sugar), hollandaise sauce (butter and vinegar)
Explain how quality is assured in egg production in order to minimise food safety risks (producers)
Bord Bia quality Mark is only obtain by a producer if their farm is audited to ensure;
- participation in routine salmonella testing of hens to prevent salmonellosis in humans, all hens must be certified salmonella free
- accurate records are kept of the origin, sex, age, breed, movement and vetinary treatments of all hens to ensure full traceability
- all feed given to hens is heat treated to reduce bacterial contamination
In relation to eggs, what is organic?
2
Organic eggs come from birds that are fed special organic feed that is not treated with chemical pesticides or fertilisers
The birds are also not treated with growth hormones or given antibiotics
Outline the factors to be considered when storing eggs
7
Store eggs in a fridge at 4 degrees as room temperature speeds up bacterial growth which increases the rate of spoilage
Store eggs away from strong smelling food such as fish as their porous shells can absorb odours
Ensure eggs are stored with the pointed end down to prevent the chalazae from breaking and the egg yolk becoming damaged
Leftover whites should be refrigerated in an airtight container for two to four days.
Leftover yolks should be refrigerated in water for two to four days to prevent drying out.
Minimise the amount of time eggs are in storage.
Use within the best before date
Name four nutrients found in eggs
16
Vitamin A Vitamin D Vitamin E Vitamin K Thiamine (B1) Riboflavin (B2) Niacin (B3) Cobalamin (B12) HBV protein Saturated fat Calcium Phosphorus Zinc Sulphur Non-haem iron Water
Describe the nutritive value of eggs
(Proteins)
(3)
An excellent source of high biological value protein
Proteins ovalbumin and globulin in the white
Proteins vitellin and livetin in the yolk
Describe the nutritive value of eggs
(Fat)
(3)
Saturated fat is present in the yolk - dispersed as a fine emulsion due to the presence of lecithin
Cholesterol in the yolk
White is fat-free
Describe the nutritive value of eggs (Carbohydrates)
Lack carbohydrates so they should be served with high carb foods such as bread
Describe the nutritive value of eggs (Vitamins)
3
B-group vitamins particularly thiamine (B1) riboflavin (B2), niacin (B3) and cobalamin (B12)
A, D, E and K vitamins are found in the yolk (vitamin A beta-carotene gives the yolk its colour)
Eggs lack vitamin C
Describe the nutritive value of eggs (Minerals)
5
Calcium Phosphorus Zinc Sulphur Non-haem iron in the yolk
Describe the nutritive value of eggs (Water)
High water content with the majority found in the white
Explain how food labelling on eggs is beneficial as a source of consumer information
EU legislation requires that individual eggs be stamped with a code to ensure full traceability of the egg to the farm
A number to distinguish production/rearing method e.g. 0 (organic), 1 (free-range)
Two letters denoting the country of origin e.g. IE for Ireland
A code containing a letter and a number to identify the country and producer the egg came from e.g. D68
The date of minimum durability e.g. 07/04
Explain how quality is assured in egg production in order to minimise food safety risks (packaging plant)
Bord Bia quality Mark is only obtained by a packaging plant if they have been audited to ensure:
- implementation of a thorough sanitation and pest-control programme
- staff who operate or monitor any critical control point (CCP) receive HACCP and food safety training
