We all know “eggs” … and to most of us, those are what we have for breakfast. But there is much more depth to this prehistoric culinary item than just food. Eggs are laid by many different kinds of animals, including fish, amphibians, reptiles, birds, and insects. Eggs belonging to birds and reptiles possess a protective eggshell that contains a vitellus (called an egg yolk) and an albumen (called an egg white) that exists within various thin membranes. In regards as food eaten by humans, the most popular “eggs” found on the table are those of chickens, ducks, quail, and fish eggs such as roe and caviar. Within these egg yolks is a significant amount of choline and protein. Due to the high “protein” content of an egg, the US Department of Agriculture lists “eggs” within the “meat” group of the Food Guide Pyramid. Chicken eggs, being a primary part of the human diet, is mass produced as a global industry. Bird Eggs have been dined on since prehistory from early hunter-gatherers on through domestication in farming. The chicken is believed to have been first domesticated from a jungle fowl native in Southeast Asia and India before 7500 BCE for its egg and meat. This is ample evidence that chickens were first introduced to Sumer and Egypt by 1500 BCE and Greece by 800 BCE. Ancient Hieroglyphics dating from 1420 BCE in Thebes, Egypt show a man carrying a bowl of ostrich eggs, possibly a pelican egg, and other eggs as offerings. Some wild bird eggs are protected – from collecting them, selling them, or eating them.
Folklore: The Ancient Romans would crush the egg shells in their plates to prevent evil spirits from hiding there. Taboos on eggs occur in Christianity during Lent (Middle Ages) because eggs were seen to be too rich.
Cooking: One of the most common ingredients in cooking. Duck eggs, goose eggs, quail eggs, and ostrich eggs are considered to be culinary delicacies. Gull eggs are considered a delicacy in England and Norway. In some African countries, guinea fowl eggs are also common food source. Pheasant eggs and emu eggs are also eaten. During the 17th century, in France, it was popular to scramble eggs with acidic fruit juices. This practice is believed to be the origin of lemon curd. During the 19th century, the dried egg industry was developed just before the frozen egg industry. 1878 in St. Louis, Missouri, the first account of drying eggs by transforming the egg yolk and whites into a light-brown, meal-like substance was conducted, and blossomed by the World War II to be used for food with military troops. By 1911, the Egg carton was invented by Joseph Coyle of British Columbia to solve a dispute between a farmer and a hotel owner when eggs delivered were found broken. Originally made of paper, these cartons expanded to cardboard, plastics, and glass. Egg whites solidifies when it reaches 144-149 degrees Fahrenheit (62.2-65 degrees Celsius) and the Egg Yolks coagulates a bit higher temperatures at 149-158 degrees fahrenheit(65-70 degress Celsius). If overcooked during boiling, a green ring will appear around the egg yolk due to the iron and sulfur compounds in the egg but does not affect taste, however overcooking will decrease the protein quality of the egg. Chilling an egg for a few minutes in cold water until completely cooled will prevent the greenish ring forming on the surface of the yolk when boiled. Cooking also increases the risk of atherosclerosis due to increased oxidation of the cholesterol contained in the egg yolk.
Eggs from chickens are the most commonly used for cooking in the world for both sweet and savory dishes, baked goods, or simply as a daily breakfast meal. As a dish itself, it is often boiled (soft or hard), fried, scrambled, added to a piece of toast for an egg-in-the-nest, pickled, or added as an ingredient to pancakes, waffles, or french toast. They are also eaten raw, drank in protein drinks or shakes, and enjoyed as a supplement to beauty enhancers for hair and skin. There is a safety issue with raw eggs in the modern world, as raw eggs can lead to salmonellosis and the raw protein in eggs is only 51% bio-available and not very absorbed by digestion. Protein Absorbtion increases to 91% bio-available when cooked. Egg whites (aka albumen) contain little to no fat, but full of protein, and often cooked separate from the yolk as a additional ingredient in baking and cooking, especially with breads, desserts, puddings, mousse, and meringues. Ground egg shells are often used as a food additive to add calcium. The birds diet will affect the flavoring of the egg. Chickens that eat rapeseed or soy meals will create a fishy smelling triethylamine addition to the taste of the eggs which is often a problem for free-range hens. Eggs can be soaked into mixtures to absorb the flavors as well.
Preservation: In order to prevent food poisoning and salmonella, the handling of eggs will vary from culture to culture, country to country. In the Unied States, the USDA recommends refridgerating eggs to prevent the growth of Salmonella – and this is why in America, you won’t find eggs on the dry shelves like you do in Europe – especially Germany, Ireland, France, and the United Kingdom. Refridgeration is believed to preserve the taste and texture of eggs, but it has been found that un-cracked eggs can be left unrefirgerated for several months without spoiling. Eggs can also be preserved with salt as it draws water out of bacteria and molds preventing its growth. Salted eggs are a culinary delicacy, such as the chinese salted duck egg which is created by immersing duck eggs in brine or coating them with a paste of mud, clay, or salt. These are then boiled before consumption after about a month of absorbtion and served with rice congee. Pickling of eggs is also commonplace as is hard boiling. Boiling the egg and then immersing in a concoction of salt, vinegar and spices (ex. allspice, garlic, or ginger) and/or beetroot juice is used in pickling of eggs. If immersed in beetroot juice for several days, the red coloring will reach the yolk, and if marinated for several weeks or more with the vinegar will dissolve the shell’s calcium carbonate and penetrate the egg making it viable to keep eggs for a year or more without refrigeration. One of the culinary delicacies as well as one of the best preserved eggs is called the “Century Egg”. This 100 year old egg is created by coating an egg with a concoction of lime, salt, ash, clay, and rice straw and let sit for a few weeks upwards to several months. After “sitting”, the yolk becomes dark green and cream-like with full odors of sulfur and ammonia, with the white becoming dark brown to transparent jelly-like substance having a mild and distinct flavor. They are popular in Asian countries.
Alternatives to Eggs for Cooking: Cooking can be quite difficult without the use of eggs as almost all baking recipes at least include them. Alternatives have been found, especially for vegetarian, vegan, and egg-intolerant populations. These include ground flax seeds, applesauce, arrowroot, banana, extracted soybean lecithin, tofu, and potato starch flour are all good alternatives that create a binding-like or rising agent similar to eggs.
Science:
Egg shapes vary, but generally have a prolate spheroid or ovate shape with one end larger than the other and a cylindrical symmetry along its long axis. “egg” is actually surround by a thin hard shell that protects the egg matter. The Egg matter consists of an egg “yolk” that is suspended by 1-2 spiral bands of tissue called the chalazae. Yolks that are in newly laid eggs are round and firm. As time goes by, it absorbs water from the albumen increasing its size and causing it to stretch and weaken the vitelline membrane flattening and enlarging the yolk shape. The white liquid or “albumen” (aka glair, glaire) is formed from the layers of secretions of the anterior section of a bird’s oviduct during passage of the egg, forming around fertilized and unfertilized yolks to protect the yolk and aid additional nutrition for the growth of the embroyo. This consists often upwards of as high as 90% water and 10% dissolved proteins (mucoproteins, globulins, and albumins) and contain almost no fat and less than 1% carbohydrate content. There is an “air cell” at the larger end of the egg that forms when the contents of the egg cool down and contract after it is laid. In production of chicken eggs, this air cell is used to grade eggs, based on the size of the air cell. Fresh eggs possess a small air cell and get a grading of “AA”. Once the egg’s air cell increases, the quality of the egg decreases, and grading of eggs move from “AA” to “A” to “B”. Grading can be tested by floating an egg in water, the less dense and the larger end of the egg will rise to increasingly shallow depths. Very old eggs will float in water and are not advised to be eaten. Eggshells vary in color based on the pigment deposition from egg formation in the oviduct differing from species and breed but with a spectrum from white, brown, pink, and speckled blue-greens.
Health: Half of the calories found in eggs come from the fat in the yolk. Those seeking a low-cholesterol diet should reduce egg consumption, although only 27% of the fat in eggs are saturated fats, palmitic, stearic, and myristic acids that contain LDL cholesterol. Egg whites contain primarily water and protein with little to no fat or cholesterol. Some nutritionists discourage eating the egg yolk due to controversial beliefs about health risks with them such as high cholesterol, cardiovascular disease or strokes, type 2 diabetes, and coronary heart disease. Eggs can become contaminated by the pathogenic bacteria Salmonella enteritidis as well as with other members of the Salmonella genus due to exposure to fecal matter from its host. Eggs are quickly washed with a sanitizing solution often within minutes of harvested eggs being laid and most of the concerns relate to sanitary conditions where the hosts are kept, farmed, or raised. Health experts recommend always refrigerating eggs and using them within 2 weeks, cooked thoroughly, and never to consume them raw. Eggs should not come in contact with food preparation or ready-to-eat food. Egg allergies are common today in infants, but usually dissipates once the child grows older. Allergic reactions tend to be to egg whites more than egg yolks.
In religion, mythology, and folklore eggs are a symbol of life and are often celebrated as such. A popular tradition to celebrate eggs are the pracice of decorating or coloring them. This is popular throughout the world in celebration of Pagan Eostre or the Spring Equinox and Christianity’s Easter celebrations. These include dying eggs, hiding them, and having an easter egg hunt. The popular games and rituals have seen a mutation to plastic eggs containing toys or candy in the hunts in the modern day due to health and safety issues with boiled eggs left outdoors. It is also a very popular craft in the Czech Republic and Persian cultures. The Persian New year tradition of “Norouz” consists of family members decorating hard-boiled eggs and setting them together in a bowl. The “dancing egg” tradition, celebrated since the 16th century in Spain, consists of an emptied egg positioned over a water jet or fountain to be suspended dancing turning without falling. Eggs are used in mischief, especially Halloween and high school or college pranks involving “egging” by throwing eggs at houses, cars, and people.
Article by Thomas Baurley
Bibliography/References:
- About.com: Calorie Count – Calories of Eggs. Website referenced July 2012. http://caloriecount.about.com/calories-egg-whole-i1128
- Britegg.com: British Egg Information Service. Website referenced July 2012. http://www.britegg.co.uk/
- Did You Know: Eggs. Website referenced July 2012. http://didyouknow.org/eggs/
- Live Science: A Dozen Facts about Eggs. Website referenced July 2012. http://www.livescience.com/10043-dozen-extraordinary-egg-facts.html
- Self.com: Nutritional Data Facts about Dairy and Egg Products. Website referenced July 2012. http://nutritiondata.self.com/facts/dairy-and-egg-products/111/2
- Wikipedia: The Free Encyclopedia. “Eggs”. Website referenced July 2012. http://en.wikipedia.org/wiki/Egg_(food).
