Eggs as food

Humans and other hominids have eaten eggs for millions of years, making them a very old and important food. The most common eggs people eat come from fowl, especially chickens. In places like Southeast Asia, people have been eating chicken eggs since around 1500 BCE.

Besides chicken eggs, people also eat eggs from other birds, like ducks and ostriches, though these are not as common. Some people also eat the eggs of reptiles, amphibians, and fish. When we eat fish eggs, we call them roe or caviar.

Today, hens and other egg-laying animals are raised all around the world. The making of chicken eggs has become a huge business, with millions of tons produced every year. However, there are many discussions about the best ways to raise these animals, especially after the European Union decided to stop some old methods in 2012.

History

Bird eggs have been important food since ancient times, both for people who hunted wild birds and for cultures that raised birds for farming. The chicken was likely first raised for its eggs from jungle fowl in tropical and subtropical areas of Southeast Asia and the Indian subcontinent before 7500 BCE. Chickens were brought to places like Sumer, Egypt, and Greece thousands of years ago. In ancient Rome, eggs were often used to start meals, and people would crush the shells to keep away evil spirits.

During the Middle Ages, eggs were not eaten during Lent because they were rich, and also to give farmers a break and save food during scarce times. In the seventeenth century in France, people enjoyed scrambled eggs mixed with acidic fruit juices, which may have led to the creation of lemon curd. The idea of dried eggs began in the nineteenth century and became very important during World War II for feeding soldiers. The egg carton was invented in 1911 to protect eggs better, and today, more eco-friendly paper cartons are popular again. Through many years of careful breeding, chickens now lay many more eggs each year than their wild ancestors did.

Varieties

Bird eggs are a common and versatile food used in cooking and the food industry. The most commonly used eggs come from chickens, ducks, and geese. Smaller eggs, like quail eggs, are sometimes used as a special ingredient in Western countries. In Asia, such as China and Thailand, eggs are a regular part of everyday meals, and Asia produced about 59 percent of the world's eggs in 2013.

Larger eggs, such as those from ostriches, are usually treated as a luxury. Gull eggs are considered a delicacy in England and some Scandinavian countries, like Norway. In Africa, guineafowl eggs can be found in marketplaces, especially in spring. Pheasant and emu eggs are edible but less common and may be found at farmers' markets or special grocery stores. In many places, laws protect wild bird eggs, so they can only be collected or sold at certain times of the year.

Production

In 2017, the world produced 80.1 million tonnes of chicken eggs. China was the largest producer, followed by the United States, India, Mexico, Japan, and Brazil and Russia. During production, eggs are sometimes candled to check their quality. This helps determine the size of the egg's air cell and whether there might be an embryo inside.

Anatomy and characteristics

Bird and reptile eggs have a protective shell, egg white, and egg yolk inside. The yolk is held in place by spiral bands of tissue called chalazae. The larger end of the egg often contains an air cell that forms after the egg is laid.

Eggshell color depends on the bird’s breed and diet, ranging from white to brown to blue. Egg white is mostly water and protein, and it turns solid when cooked. The yolk’s color depends on the hen’s diet, with yellow or orange plant pigments making it brighter. Some eggs can have two yolks or no yolk at all, which happens due to timing issues during the egg’s formation.

Culinary properties

Chicken eggs are used in many dishes, both sweet and savory, such as baked goods, scrambled, fried, poached, boiled, and omelettes. Egg yolks help mix ingredients together and make dishes thicker, like in custards. Egg whites are filled with protein and can be whipped to make light, fluffy desserts such as meringues and mousse.

Eggs change when heated, with the yolk solidifying between 61 and 70 °C (142 and 158 °F) and the white between 60 to 73 °C (140 to 163 °F). Cooking eggs safely helps prevent illness from bacteria. Different methods, like soaking eggs in flavored mixtures, can change their taste. For example, tea eggs are flavored with spices, soy sauce, and black tea. Proper storage and preservation, such as using salt or vinegar, help keep eggs fresh and safe to eat.

Nutrition and health effects

Eggs are a great source of protein and choline. The United States Department of Agriculture used to call eggs "Meat" in its old food guide, but now uses MyPlate. Eggs score very high for protein quality.

A medium chicken egg has about 70 kilocalories and 6 grams of protein. Cooking eggs changes their nutrition a little. For example, scrambled eggs lose a small amount of vitamin B12, while lightly fried eggs lose a bit more. Hard-boiled eggs lose the most.

The food we give hens can change the eggs. Hens that eat special foods like fish oil or flaxseeds make eggs with more good fats.

Cooked eggs are easier to digest and safer than raw eggs because they reduce the risk of getting sick.

Cholesterol and fat

Most of the calories in eggs come from the fat in the yolk. An egg has about five grams of fat, some of which is good for you. The egg white has almost no fat or cholesterol.

Some people worry about the cholesterol in egg yolks, but eating one egg a day usually does not harm healthy people’s hearts.

Type 2 diabetes

Studies do not agree on whether eating eggs changes the risk of type 2 diabetes. Some studies say eating many eggs might increase the risk, while others say it does not.

Cancer

Some studies say eating many eggs might increase the risk of certain cancers, but other studies do not find this to be true.

Cardiovascular health

Studies also do not agree on whether eggs affect heart health. Some say eating many eggs might increase the risk of heart problems, while others say eating up to one egg a day is safe for most people.

Other

Eating eggs does not seem to increase the risk of high blood pressure or stroke. Eggs also do not seem to cause inflammation in the body.

Contamination

Eggs can sometimes have harmful bacteria like Salmonella enteritidis. To stay safe, wash eggs right after they are laid, keep them cold, and cook them well. Most eggs in the U.S. are safe, but in some other countries, there have been problems with eggs having bad bacteria or chemicals.

Food allergy

Eggs are one of the most common food allergies for babies. Many babies outgrow their egg allergy as they get older. People with egg allergies need to read food labels carefully.

Farming

See also: Poultry farming

Most chicken eggs sold for eating are unfertilized because hens are kept without roosters. Both fertilized and unfertilized eggs are safe to eat and have similar nutrition. Fertilized eggs won’t have a developed embryo because refrigeration stops the cells from growing.

Eggs are graded by quality and size. In the United States, the Department of Agriculture grades eggs by how clear and firm the egg white is and how round and centered the yolk is. Grade AA and Grade A eggs are best for cooking because they look nice.

The color of an eggshell doesn’t change how the egg tastes, but some places prefer certain colors. In many parts of the United States, white eggs are common, while brown eggs are popular in places like New England. Brown eggs are also preferred in China, France, and the United Kingdom. Some small farms sell eggs of many colors, such as white, brown, speckled, green, and blue.

Cultural significance

Further information: Egg decorating and Easter egg

Eggs have played an important role in many cultures, especially during celebrations. In some places, people decorate hard-boiled eggs for Easter, often by dyeing or painting them. In parts of the world influenced by Persia, families decorate eggs before the spring equinox during the Persian New Year called Norouz.

In Northern Europe and North America, children often enjoy Easter egg hunts, where adults hide decorated eggs for them to find. In Eastern and Central Europe, and some parts of England, people might tap eggs together to see whose egg stays unbroken. In Barcelona and other Catalan cities, a special tradition during the feast of Corpus Christi involves balancing a hollow eggshell on a fountain’s water jet, making it spin without falling.