Comprehensive Overview of Eggs

INTRODUCTION TO EGGS

  • All animals, including birds, lay eggs. Mammals, however, typically give birth to live young.
  • Egg-laying does not necessarily require mating, and the eggs laid are not always fertilized.
  • The best quality egg is fresh and unfertilized, as no one wants to see a living organism upon breaking the egg.

EGGS

  • A healthy chicken can lay one egg per day, influenced by diet and daylight exposure.
  • Egg size depends on the hen's diet and age.
  • Yolk color varies based on the hen's diet, with yellower corn resulting in a yellower yolk compared to wheat and barley.
  • Eggs are rich in protein, with two main proteins:
    • Albumen in the white
    • Lecithin in the yolk

STRUCTURE OF AN EGG

  • Shell: The outermost protective layer made of calcium carbonate; shell color depends on the hen's breed.
  • Yolk: The yellow part of the egg, whose color deepens based on the feed.
  • Vitelline membrane: A clear seal that holds the yolk.
  • Chalaza: Twisted strands of egg white that anchor the yolk to the center of the egg.
  • Shell Membrane: There are two membranes (inner and outer) that protect against bacteria; an air cell forms between these layers.
  • Air Cell: Formed as the egg contents contract after being laid.
  • Thin Albumen: Nearest to the shell; flows freely when the egg is broken.
  • Thick Albumen: Surrounds the yolk; an excellent source of riboflavin and protein.

CLASSIFICATION OF EGGS

  • Basis of Classification Types: Based on source, farm & feed.

  • Grades and Sizes:

    • US Standards:
    • AA: Jumbo, Extra Large, Large
    • A: Extra Large, Large, Medium
    • B: Medium, Small
    • European Standards:
    • Egg sizes graded from Extra Large to small based on weight in grams.

  • Weight Classification (US):

    • Extra Large: 73g
    • Large: 63g
    • Medium: 53g
    • Small: 45g and below

TYPES OF EGGS

  • Types of eggs include:
    • Chicken, Duck, Goose, Guinea fowl, Gull, Ostrich, Partridge, Pheasant, Quail, Plover, Turkey, Thousand year old eggs.

SELECTION OF EGGS

  • Eggs are graded based on factors such as freshness, cleanliness, size, cracks, and color.
  • Candling: Process used to check eggs' inner conditions.
  • Bloom Examination: A thin lime coating helps assess freshness.
  • Water Test: Fresh eggs sink; older ones float.
  • Shaking Test: Fresh eggs have more liquid, older eggs feel heavier as contents have evaporated.

STORAGE OF EGGS

  • Eggs should be stored in a refrigerator for daily use or industrially above freezing with controlled humidity and CO2.
  • Proper storage method can prolong egg life up to 9 months.
  • Long Storage Methods:
    • Freezing: Mixed yolk and whites are quick-freezed in sterilized containers.
    • Drying: Eggs are mixed and spray-dried at 71 °C.
  • In hotels, eggs should be unwashed and consumed within a month.
    • Hard-boiled eggs unshelled can be stored for 4 days, shelled for 2 days.
    • Desserts containing eggs should be used within 24 hours.