1. EGGS

2. PROPERTIES
Coagulation properties – trap milk when heated to form custards
Provide structure to foods
Contribute to texture by influencing flavor, smoothness, moistness

3. NUTRITIVE VALUE 75% Water 12% Protein 10% Fat 1% Carbohydrate
1% minerals

4. LIPIDS Almost all in yolk Triglyceride- almost all of eggs fat (66%)
Phospholipids – lecithin (28%)
Cholesterol – change in diet decreases amount of cholesterol (5%)
Lecithin – naturally occurring emulsifier
Negligible in albumen

5. PROTEINS

6. OVALBUMIN Major protein in egg white – 54% of total solids
Globular protein – easily denatured
Contributes to structure of products

7. OVOTRANSFERRIN 12% of egg white
Complexes with iron and inhibits growth of bacteria dependent on iron
Not easily denatured by physical agitation
Very susceptible to denaturation by heat when not bound by iron

8. OTHER PROTEINS
Ovomucoid – 11% of white solids, resistant to heat denaturation, inhibits proteolytic enzyme trypsin
Ovomucin – 3.5% of solids, foam stabilizer, involved in deterioration and thinning of egg white as it ages
Lysozyme – 3.4%, hydrolyze polysaccharides in walls of certain bacteria

9. OTHER PROTEINS Avidin – minute amounts
Presence has nutritional significance
In natural state, binds with biotin – biotin cannot be absorbed
Heating inactivates
Vitellin and Lipovitellinin – lipoproteins that function as emulsifying agents, surrounds yolk

10. CARBOHYDRATES Very small Form of glucose, mannose, galactose
Glucose and galactose react with proteins in Maillard reaction
Produce undesirable brown discoloration in dried and cooked egg whites

11. VITAMINS AND MINERALS Shell – mainly calcium
Yolk – phosphorus, iodine, zinc, iron (not well absorbed)
Riboflavin – primarily in white
Yolk – Vitamin A (fat & carotenoid pigments)
Vitamin D, folic acid, pantothenic acid and B12

12. PIGMENTS
Yolk – orange, red, yellow pigments – carotenoid pigments, found in yellow corn, green grass, alfalfa
Xanthophyll - comes from animal feed- not a precursor to vitamin A
Colorless sac, vitelline membrane surrounds yolk
CHALAZAE - white cord to hold yolk in place

13. STRUCTURE - SHELL Semi-permeable Porous - CO2 and H2O losses
Air cell - formed as two keratinlike membranes separate
Antibacterial
Color – breed of hen, no effect on nutritional quality

14. AGING CHANGES Yolks enlarge, less viscous, flatten, no longer centered
Whites - thinner
Contents shrink - H20 losses
pH changes from 7.6 allows bacterial growth

15. INSPECTION FDA and FSIS share responsibility for egg safety
1999 egg safety plan to eliminate eggs as source of Salmonella enteridis
2000 safe handling procedures on cartons

16. GRADING Letter grades Nutritive value remains the same
Shell - shape, texture, soundness, cleanliness
Interior - white, yolk, air cell size
Candling - view of shell and inside of egg

17. INSPECTION 1970 Egg Products Inspection Act Established standards
Inspects plants processing eggs
Wholesome and unadulterated and truthfully labeled egg products
Imported eggs must meet same requirements as domestic

18. EGG SIZE Not a part of quality Size = weight per dozen
Younger chickens lay smaller eggs
3 ounces per dozen between each class
1 egg = ~ 1/4 cup or 4 T

19. PROCESSING AND PRESERVATION
Mineral oil - same day laid, partially closes pores = less microorganism permeability
egg holds more moisture retains more CO2 so resists pH

20. PASTEURIZATION Destroys microorganisms
Required of all commercial liquid, dry or frozen products
Must maintain functional qualities
Ultrapasteurization with aseptic packaging - 10 week shelf life,
Salmonella, listeria, E.coli free
Now pasteurized eggs in shell

21. FREEZING Pasteurized prior to freezing Uncooked retain properties
Cooked - syneresis when thawed
Yolks become gelatinous or lumpy when thawed
Retard gelatination by adding salt, or sugar or corn syrup

22. DEHYDRATION
Began in 1870s
Whites - remove glucose before drying (to prevent Maillard reaction), whipping aid is added to help with foams
Add sugar to egg white to aid in hydration
Yolks - irreversible changes in lipoproteins

23. STORAGE Cold temperatures High humidity Hard cooked eggs - 1 week
Whites - 4 days
Yolks days
Whole eggs in cartons, will absorb odors

24. PREPARATION PRINCIPLES
Centers around ability of proteins to coagulate when heated
Coagulation – protein molecules attract
and hold large quantities of water around them
Gel formation – Solid particles held suspended in a liquid
Whites and yolks coagulate at different temperatures
Whites at F; yolks at F

25. HEAT Denatures, coagulates to form gel
Egg white – transparent viscous masssoft, white, opaque gel
Heat past 1580F white becomes tough, porous
Excessively high temperatures egg white gel loses water, shrinks, toughens
High temps yolks become crumbly in texture
Heat too quickly coagulated proteins curdle

26. AGITATION Denatures proteins
Disrupts bonds and initially causes foaming
As more air incorporated  soft foam gets larger and stiffer because increased denaturation
Denatured proteins eventually curdle separate into fluffy masses and become dry as liquid drains out

27. ACID Lower coagulation temperature
Too much  proteins denature severely and gel curdles
pH greater than 9 or lower than 5  hardness and cohesiveness greater
Prolonged heating  peptidzation of protein and thinning of mixture (pie fillings become thin and runny)

28. SUGAR Elevates temperature for coagulation
The more sugar the greater the heat needed for coagulation
More tender coagulum

29. SALT Lowers temperature for coagulation
Curdling may result from stirring gel so add salt before heating

30. STARCH Coagulation and gelatinization occur at different temperatures
Bring starch mixture to maximum thickness before adding uncooked egg

31. OTHER CONSIDERATIONS
DILUTION - coagulation temperature elevated if egg mixture is diluted
CONCENTRATION OF EGG – lowers coagulation temperature

32. COOKING CHANGES
Frying - coagulates protein, overheated pan overcoagulates egg  tough
Hard cook - more tender if done at simmering not boiling temperature
Color - green with long and high heat exposure due to formation of ferrous sulfate
Old eggs – ferrous sulfate may form due to increase in alkalinity

33. FOAMS Created as whites are beaten to incorporate air
Holds shape as protein coagulates around air cells
Provides leavening - dry foam not as effective as soft
Yolks contain fat - physically interferes with alignment of protein around air cells

34. MERINGUES Sweetened foams
Weeping - release of water from undercooked or undercoagulated whites
Beading - overcooked or overcoagulated meringues

35. FACTORS AFFECTING FOAMS
TEMPERTURE - room temperature best, but microbial growth a problem
pH - ACID - beginning of beating = less volume, more stability, should be added after eggs reached foamy stage and have large air cells; (cream of tartar)
SALT - adds flavor, less volume, less stability, add after foamy stage

36. FACTORS
SUGAR - less volume, add gradually at soft peak stage, after large cell and denaturation have begun; competes for water
FAT - Substantially less foaming, less volume; interfering agent
LIQUID - Increases volume and tenderness of foam, increases chance of syneresis; decreases stability

37. FUNCTIONS
Binder – such as meat loaf, coatings, proteins coagulate binding food into cohesive mass
Emulsifier – form stable emulsions, coat oil drops to prevent them from combining with each other
Foaming, leavening agent – Air bubbles expand with heat and egg white film hardens

38. FUNCTIONS CONTINUED
Interfering agent – Prevent crystals from coming together and getting larger
Clarifying agent – proteins coagulate and trap loose particles

39. EGG SUBSTITUTES NO yolks 80% egg whites
Corn oil, nonfat milk solids, calcium caseinate, soy protein isolate, soybean oil, and other substances

40. NUTRITIVE VALUE
Biological value = 100- all absorbed protein is retained in the body
Protein digestibility-correct amino acid score = measure of protein quality which compares amino acid balance with needs of a preschooler and corrects for digestibility = 1

41. SAFETY Contents of freshly laid egg generally sterile
Salmonella enteritidis - may be found inside
Egg shell - surface high level of bacteria - may enter through pores
FDA prohibits use of raw or lightly cooked eggs in food production or manufacturing facilities - must reach internal temperature of 1450F