Eggs as food

**History and Production of Eggs**:
– Bird eggs have been valuable foodstuffs since prehistory.
– Domestication of chickens for eggs likely before 7500 BCE.
– Ancient Rome preserved eggs using various methods.
– Eggs were forbidden during Lent in the Middle Ages.
– Dried egg industry developed in the nineteenth century.
– World production of chicken eggs was 80.1 million tonnes in 2017.
– Largest producers include China, the United States, India, Mexico, Japan, Brazil, and Russia.
– A large egg factory in British Columbia ships 12 million eggs per week.
– Americans are projected to consume 279 eggs each in 2019.
– Eggs are candled to check quality during production.

**Egg Components**:
– **Air Cell**:
– Forms when contents cool down and contract after laying.
– Chicken eggs are graded based on air cell size.
– Grade of AA for very fresh eggs.
– Old eggs with large air cells float in water and should not be eaten.
– **Shell**:
– Color caused by pigment deposition during egg formation.
– Quality affects egg grade.
– Thickness varies among different bird species.
– Protects egg contents from external environment.
– **Membrane**:
– Composed of fibrous proteins like collagen type I.
– Used commercially as a dietary supplement.
– **White**:
– Contains 90% water and 10% proteins.
– Important in vaccine preparation.
– **Yolk**:
– Shape changes with age and water absorption.
– Color depends on hen’s diet.
– Artificial color additives are prohibited in the US.

**Culinary Uses and Cooking of Eggs**:
– Eggs used in diverse dishes.
– Yolks are emulsifiers and thickeners.
– Whites are protein-rich and fat-free.
– Ground eggshells used for calcium.
– Common preparations include scrambled, fried, and poached.
– Egg proteins gel at different temperatures.
– Overcooking leads to a greenish ring around the yolk.
– Peeling eggs is easier when boiled in hot water.

**Flavor, Storage, and Preservation of Eggs**:
– Bird’s diet affects egg flavor.
– Proper storage crucial to prevent food poisoning.
– US refrigerates eggs to prevent Salmonella growth.
– Salt preserves eggs by drawing out water.
– Chinese salted duck eggs are made by immersing in salt.
– Pickled eggs can be preserved in brine or coated with a salt and mud/clay paste.
– Some pickled eggs are colored with beetroot juice.
– Nutritional value of pickled eggs includes being a good source of protein and essential vitamins.

**Pickled Eggs**:
– Preparation methods and color variations.
– Nutritional value and serving suggestions.
– Cultural significance in various cultures and settings.