eggs

Importance of Eggs

• Contain everything needed to sustain the life of a new chick
• An excellent source of many nutrients
• Can be eaten alone
• Versatile food to prepare
• Can be fried, scrambled, poached, hard-cooked
• Invaluable ingredient for many recipes

US Egg Consumption

• Per capita consumption of eggs have increased 15% in the past 20 years according to the USDA
• The production of US Egg Shells is about 7.8 billion per month
• Over half of all US eggs are sold as shell eggs through retail stores and over a quarter of eggs produced get processed into products for food service, manufacturing, retail, and export
• The majority of US egg production is consumed domestically

US Egg Production

• 30% of eggs are produced in either cage-free or free-range systems
• Floor: hens have access to the barn or housing floor, usually covered with litter and nesting boxes for egg laying
• Aviary: Several levels of perches
• Cage-free systems keep laying hens indoors
• Free-range systems mean that laying hens have access to the outdoors
• 70% of eggs are produced in conventional cage systems
• Wire cages that may hold 6-10 laying hens
• Usually have automated feeding, watering, and egg collecting systems
• According to United Egg Producers, cage systems typically provide each laying hen an average of 67 square inches
• Cages control disease and provide cleaner eggs compared to traditional production and is more economically efficient

Composition of Eggs

• Yolk
• 30% of the egg's weight
• Water, fat, and protein
• Color of the egg is determined by the hen's diet
• Pigments in the feed and artificial color is not allowed
• Vitelline membrane surrounds yolk
• Albumen (egg white)
• 58% of the egg's weight
• Water and protein
• 2 layers, thick and thin
• Chalaza (a cord) anchors the yolk to the center of the white
• There are 2 shell membranes
• There is an air cell between the 2 shell membranes
• Shells
• 12% of the egg's weight
• Composed of calcium carbonate
• Protected by cuticle or bloom
• Color indicates the breed and has no correlation to nutrient content or flavor (white vs brown eggs)
• Cuticle (bloom) is a waxy coating that can seal pores from bacterial contamination

Why refrigerate eggs?

• Whether you refrigerate an egg depends on the source of eggs and the danger of salmonella
• Salmonella can be caused in-vitro or by external contaminants
• Some countries deal with that by
• Cooking through an egg and making sure the egg is clean and refrigerating it
• Or by putting a vaccine in the egg and putting the cuticle coating on the egg shell, allowing you to keep it at room temperature.

Temperature and Time on Eggs

• Keep temperature low
• Overheated proteins become tough and rubbery and shrink from dehydration
• Consider coagulation temperatures
• Egg whites coagulate before yolks at 140-149F, yolks coagulate at 144-158F, and the whole egg starts to coagulate at 156F
• Since egg whites coagulate before yolks, whites can be cooked till firm while yolks can remain soft
• If you see a green ring around cooked yolk
• Iron and sulfur react in overcooked eggs and give off strong off-odor
• The reason is overcooking and slow cooling
• Only happens when boiling eggs because of pressure from boiling
• Hydrogen sulfide gas moves from egg white to yolk
• Reaction is caused by sulfur in white and iron in yolk which leads to ferrous sulfide
• Remedy is to avoid overcooking and cool eggs quickly after cooking by placing in an ice bath or continuously run under cold water

Effects of added ingredients

• Some ingredients can cause an increased coagulation temperature
• Coagulation occurs later and can potentially cook for longer
• Ingredients like sugar and milk
• Some ingredients decrease the coagulation temperature
• Coagulation occurs sooner
• Ingredients like salt and acid

Macronutrients of Eggs

• Calories
• 75 calories per eggs
• Protein
• One large egg contains about 7 grams of complete protein
• 4g from the whites and 3g from the yolk
• The majority of protein (54%) is ovalbumin in the egg white
• Fat
• Egg yolk contains about 5 grams of fat
• ~2g monounsaturated, ~2g saturated, ~1g polyunsaturated
• Cholesterol
• 185mg in large egg

Micronutrients

• Vitamins
• Contain all fat-soluble vitamins: A, D, E, K
• Water soluble: B2, B12, folate, biotin, and panthothenic acid
• Minerals
• Selenium, iodine, zinc, iron, copper
• The iron is not bioavailable
• Binds with phosvitin which is a protein that inhibits absorption

Value-Added Eggs

• Have special attributes because of nutrient content
• Examples
• Lower-cholesterol eggs
• Higher omega-3 fatty acids
• Vitamin E levels
• Animal friendly practices, like free-range

Egg Products Inspection Act (1970)

• Inspection: Majority is done by the USDA
• Egg processing plants must be inspected
• Eggs & egg products must be wholesome, unadulterated, and truthfully labeled
• Enforced by USDA poultry division
• Applies to all eggs, even imported eggs
• Fail inspection: Usually electronic detection
• Cracked shells, broken membranes, dirty/stained, greenish egg whites, rotten, moldy, bloody
• Not allowed to be sold whole

Candling Eggs

• Process that allows for the grading of the interior contents without cracking the egg open
• Egg start to deteriorate the minute they are laid
• The white thins with age, making it easier to see the yolk
• Testing freshness
• Crack it open onto a flat surface and look at the height of the albumen
• Fresh egg whites sit up tall and firm and older ones spread out

Grading Eggs

• Grading is voluntary. It is paid by the producer and performed by the USDA.
• The best quality eggs are USDA Grade AA + Grade A
• Sold at supermarkets
• Firm and high in albumen
• Lowest grade is USDA Grade B
• Not sold directly to consumers
• Used as ingredients in other food products

Storing Eggs

• Egg shells are not airtight
• Tiny pores are found all over shell
• Air cell increases in size as egg ages because moisture and CO2 escape through the pores
• Best to keep eggs in original carton
• Retain moisture
• Prevents absorption from other flavors and odors

Egg Carton Label

• According to the USDA, many eggs reach the stores only a few days after the hen lays them
• The carton's labels include:
• The day the eggs were cleaned, graded, and placed in the carton
• The sell by date, which may not exceed 45 days from the date of pack
• As long as the eggs were kept refrigerated, the eggs are safe to eat past the sell by date

Egg Sizing

• Sizing is not related to grading
• Egg sizes are determined by a minimum weight for a dozen eggs in their shell
• Egg sizes: Jumbo, Extra Large, Large, Medium, Small, Pee Wee

Egg Safety

• According to the CDC, eggs are implicated in 73% of all salmonella outbreaks
• Eggs are high risk foods due to their high water content and high protein content
• Potential causes for bacterial contamination
• Transfer of salmonella from hen's ovary
• Transfer of salmonella from fecal matter during laying
• Food handling cross contamination after eggs have been removed from shell
• Cooking eggs in infected water
• Safety Recommendations
• Purchase only refrigerated eggs and store them in the refrigerator
• Cook eggs til no visible liquid egg remains
• Cook all egg dishes to 160F
• Raw or undercooked eggs should never be consumed
• Use pasteurized eggs for food items that are only lightly cooked or left raw

Main functions of eggs in food

• Emulsify
• Bind
• Color
• Foam

Emulsify

• Egg yolk contains lecithin
• One end of the molecule attracts water while the other attracts fat
• Thicken and stabilize salad dressings, sauces, and mayonnaise

Binding

• High protein content facilitates binding
• Foods dipped in egg white before battered
• Binder in meatloaf, meatballs, and lasagna

Color

• Yolk contributes to the golden brown color
• Can be seen in many pastries with egg washes

Foaming

• Egg whites can increase 6-8 times their original volume
• Used to aerate and leaven
• Puffy omelates, souffles, angel food cake, sponge cake, meringues
• How does foaming occur?
• By beating the egg whites, the protein molecules are denatured and beating also incorporates air
• The unfolded proteins rearrange themselves around the air cells
• When foam is heated, the air cells expand and the proteins coagulate, which solidifies the foam
• Factors that affect foaming
• Beating technique
• Start slow and gradually increase speed
• Test for doneness by lifting the beater out of the foam and observing the egg peak
• Avoid overwhipping because the peaks will become dull, dry, and not shiny, and the foam will separate
• Temperature
• Should be at room temperature
• Bowl
• Should be in a deep bowl with rounded bottom and sloping sides, allowing whites to be picked up by the beater
• Avoid plastic bowls as they can interfere with foam formation because a thin film of grease
• Separation of eggs
• Egg yolks contain fat which interferes with the foam
• Careful separation of egg white from yolk
• Egg separators aid in separation
• Sugar
• Stabilizes foam, but inhibits coagulation
• Add near the end of the beating or the volume may be compromised
• Salt
• Can affect stability and volume
• Rarely added or just a pinch
• Acid
• Egg whites often are alkaline at around 8.4 pH
• Lower pH creates a more stable foam
• pH can be lowered by adding lemon juice or cream of tartar