13 - Eggs

Eggs

  • Eggs contain everything needed to sustain the life of a new chick.

  • Excellent source of many nutrients.

  • Versatile food choices:

    • Can be prepared fried, scrambled, poached, hard-cooked.

    • Invaluable ingredient for many recipes.

U.S. Per Capita Egg Consumption Since 2000

  • Per capita consumption of eggs has increased by 4.8% since 2000.

  • Per capita consumption is calculated as total egg production minus exports divided by total U.S. population.

  • 2022 decrease in consumption due to highly pathogenic avian influenza (HPAI).

  • U.S. egg shell production reached 7.8 billion per month (estimate).

  • Utilization of eggs in 2022:

    • Exports: 1.7%

    • Retail Shell Eggs: 147.9 million cases (56.6%)

    • Further Processing: 76.5 million cases (29.3%)

Per Capita Egg Consumption, 2021

  • Average consumption measured in kilograms per year

  • No data available on map for specific regions.

Housing Environments U.S. Layer Population

  • Total Cage-Free: 96.1 million laying hens (as of 2021).

  • Organic: 6.8%, Cage-Free: 22.5%, Conventional: 70.7% as of December 2022.

  • Transition to cage-free production:

    • 28% of hens in cage-free by 2020, projected 66% by 2026.

Egg Production Overview

  • ~35% of eggs produced in cage-free or free-range systems:

    • Floor: hens have access to indoor areas.

    • Aviary: multiple levels of perches.

  • ~65% produced in conventional cage systems (battery cages):

    • Economically efficient with automated systems.

    • Provide average of 67 square inches per hen.

Egg Types and Definitions

  • CAGE-FREE: Laid by hens without enclosures, access to outdoors.

  • ORGANIC: Hens fed certified organic feed, access to outdoors.

  • FREE-RANGE: Hens forage in outdoor spaces.

  • NUTRITIONAL VALUE: Shell color does not affect nutrient quality.

Composition of Eggs

  • Yolk: 30% of weight; contains water, fat, protein; pigment from diet.

  • Albumen (egg white): 58% of weight; contains water and protein.

  • Shell: 12% of weight; calcium carbonate composition, cuticle prevents contamination.

Refrigeration of Eggs

  • Practices differ due to Salmonella risks:

    • Vaccination, room temperature handling, and cooking methods vary.

Cooking Eggs:

  • Temperature and Time:

    • Overheating causes toughness due to protein alteration; optimal coagulation temperatures:

      • Egg Whites: 140-149°F (60-70°C)

      • Egg Yolks: 144-158°F (62-70°C)

      • Whole Egg: Starts at 156°F (69°C).

  • Cooked white binds to B Vitamin Biotin, discouraging excessive raw consumption.

Green Ring Around Cooked Yolk

  • Caused by overcooking: reaction of sulfur in white and iron in yolk.

  • Remedy: Avoid overcooking; cool quickly.

Effects of Added Ingredients on Cooking

  • Salt/acid decreases coagulation temperature; sugar/milk increases it.

Egg Nutrition - Macronutrients

  • Calories: approximately 75 per egg.

  • Protein: around 7g per large egg (4g from white, 3g from yolk).

  • Fat: about 5g in yolk; includes monounsaturated, saturated, and polyunsaturated fats.

  • Cholesterol: 185mg per large egg.

Egg Nutrition - Micronutrients

  • Vitamins: A, D, E, K; B2, B12, folate, biotin, pantothenic acid.

  • Minerals: Selenium, iodine, zinc, iron (non-bioavailable).

Value-Added Eggs

  • Special attributes from feeding practices:

    • Lower cholesterol, higher omega-3s, animal-friendly practices.

Egg Products Inspection Act (1970)

  • USDA inspects egg processing.

  • Eggs must be wholesome, unadulterated, and truthfully labeled.

  • Inspection failure criteria include cracked shells and contamination.

Candling Eggs

  • Freshness testing without cracking eggs; white thins with age.

  • Fresh egg whites are tall and firm, older ones spread out.

Grading Eggs

  • Best quality: USDA Grade AA and A; lowest grade: Grade B (not for consumers).

  • Grading is voluntary, performed by USDA.

Storing Eggs

  • Keep in original carton to retain moisture and prevent absorption of odors.

Egg Carton Labeling

  • Eggs often reach stores soon after laying; codes indicate packaging date.

  • Safe to eat past 'Sell By Date' if kept refrigerated.

Recall Example

  • April 2018 recall of 206 million eggs by Rose Acre Farms due to Salmonella risk.

Egg Sizing and Safety

  • Sizing based on weight; not related to grading.

  • Eggs involved in 73% of Salmonella outbreaks:

    • Cooking recommendations and safety protocols include:

      • Purchase refrigerated eggs, store in refrigerator, cook thoroughly, and avoid raw consumption.

Functions of Eggs in Food

  • Critical functional roles include:

    • Emulsification in dressings and sauces.

    • Binding in meat products.

    • Foaming for aeration in baked goods.

Factors Affecting Foaming

  • Beating technique, temperature, separation of egg whites & yolks impact stability and volume.

Final Exam Reminder

  • Scheduled for next week; focus on the chemistry of cookies.