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1. The Incredible Egg
2. Egg Production Closely controlled breeding program- White Leghorns preferred favorite.
White shelled eggs
100,000 size flocks common
Each hen produces 250-300 eggs a year
3. Physical and chemical changes begin immediately after hen lays egg
Production is automated
Eggs refrigerated immediately
Temperature 40-45 F
Humidity kept high to minimize moisture loss Processing
4. Egg Carton Dating USDA requires Julian Dating, number between 1- 365
May also have an expiration date- beyond which eggs can be sold.
USDA plants expiration date cannot exceed 30 days after pack date.
Plants not under USDA- under state laws.
Fresh shell eggs store 4-5 weeks beyond Julian date without significant loss of quality.
5. Structure and Characteristics
6. Diagram of an Egg
7. Color- egg shell and yolk color vary.
Color does not alter nutrition,
8. Breed of hen determines color of shell
Color comes from pigments in outer layer
Ranges from white to deep brown.
Shell first line of defense against bacteria
Shell largely calcium carbonate- 94%
Rest small amounts of- magnesium carbonate, calcium phosphate and protein
9. Egg albumen in raw egg opalescent or clear
Appears white when cooked or beaten
Yellowish cast may indicate presence of riboflavin
Cloudiness- due to presence of carbon dioxide. Indicates a very fresh egg.
10. Air Cell Empty space between white and shell
Forms after egg is first laid.
Inner membrane cools and separates from the cell.
11. Germinal Disc
12. Egg Yolk Yolk color depend on diet of hen
Gold or lemon color preferred by consumers
Color is stable- not lost in cooking.
13. Nutritional Value Yolk 33% of liquid weight
All of fat in the egg
Less than ½ protein
Higher % of most vitamins, except ribolflavin and niacin
Yolk large egg 59 calories, whole egg 75
Albumen or egg white contains half of total egg protein
Contains all essential amino acids
14. Grading Eggs. Classified by interior and exterior quality- AA, A, or B.
Sorted according to weight and size
No difference in nutritional quality and size or color of eggs.
15. Sizing of Eggs Jumbo 30 oz.
Extra large 27 oz.
Large 24 oz.
Medium 21 oz.
Small 18 oz.
Peewee 15 oz.
16. Other Egg Characteristics Blood spot- not an embryo, often called meat spots.
Fertile eggs- develop into chicks. They are not more nutritious than unfertilized.
Organic eggs not more nutritious than non organic.
Must be free from hens not fed by rations that have pesticides, fungicides or herbicides.
17. Storage of Eggs Stored at 30 F for up to six months in the shell
Stored out of the shell for extended storage.
Food manufacturing freezes most eggs they use.
Eggs stored as yolks, or whites, or whole eggs.
Eggs can be dehydrated or powered.
18. Samonella Salmonella enteritidis found in some eggs.
2-3 eggs infected per 10,000 eggs produced.
Eggs need proper handling, storage and adequate cooking.
Watch eggs in uncooked products such as cookie dough.
19. Egg Substitutes Average egg has 240 mg of cholesterol
Egg substitutes reduce cholesterol
Made by separating the yolk from albumen or white
Yolk color added back in to albumen, but with reduced or no cholesterol.
20. Breakfast entrees
Binder for other dishes- meatloaf, croquettes
Leavening agent- soufflés, sponge cakes
Thickening agent- custards, sauces
Emulsified in mayonnaise, salad dressings
Coating agent- breads, cookies
Clarify soups and coffee
Boiled candies and frostings, retards crystallization
Garnishment as hard cooked eggs. Cooking Functions
21. Grade AA, A and B Nutritional value the same for all grades.
Grade AA stands up tall-
Large portion of thick white to thin white
Grade A yolk stands up, but white is well spread out.
B grade eggs used in
22. Reference Parker, R.O. (1999). Food science sample
lesson FS117. Retrieved September 22,
2005 from http://www.agednet.com/
Mehas, K. & Rodgers, S., (2002). Food
science. Peioria. Glencoe/ McGraw-Hill