If the prompting is heat, the albumen solidifies and becomes opaque, forming the classic cooked egg white, a high protein dish that is a favorite of body builders. Chemists used to think this process was irreversible, that there was no way to return the proteins to their raw state, but a team from the University of California in Irvine recently demonstrated a way to reverse the process, to pick apart the disrupted proteins and allow them to return to their raw state.
In effect, they managed to uncook the egg white. Although this process isn't really practical for cooks, it could have huge implications for the manufacture of complex drugs.
That's because it provides a new way to separate the chemicals produced in living cells, such as genetically engineered bacteria that produce hormones and other drugs. The yolk is a yellow sphere that contains most of the nutrients in the egg: a heady mixture of fat about 26 percent, less than a third of which is saturated fat , protein 16 percent , carbohydrates 4 percent and cholesterol about 1 percent.
Biologists like to argue over the semantics of this, but it is generally accepted that the yolk of an egg is one single, massive cell, thousands of times bigger than typical cells. The yellow yolk is most of the mass of the cell, but the important parts of the cell such as the nucleus that contains the DNA are in a small spot on the surface of the yolk called the germinal disc. This is often invisible in the eggs you buy, because they are unfertilized, so the cell has not split and grown.
It is sometimes visible as a small spot on the surface of the yolk, though, called a blood spot. If the egg was fertilized, the germinal disc is the spot where the chick would begin, as it splits into multiple cells and grows, fed by the nutrients in the yolk.
The cholesterol in egg yolks gets a bad rap: although it is an essential nutrient that plays an integral part in making cells, it was thought to have a large role in conditions like heart disease, by helping to clog the arteries.
More recent research indicates that this concern is overstated, though: this research suggests that having too much of the "bad" LDL cholesterol in the blood may not be related to eating food that contains cholesterol. Instead, it seems that other factors such as genetics and general diet may have a more significant impact than the number of eggs consumed. So, consider this the next time you eat an egg: the humble egg is a complex chemical and biological phenomenon, a fascinating mix of nutritious chemicals that is the result of millions of years of evolution and thousands of years of human manipulation.
And they taste good, too, especially on a fried-egg sandwich Be respectful, keep it civil and stay on topic. We delete comments that violate our policy , which we encourage you to read.
Discussion threads can be closed at any time at our discretion. Appliance Science: The biology of the chicken egg What is inside a chicken egg?
Noon Edition. Home Archives About Contact. By Don Glass Posted September 28, Media Player Error Update your browser or Flash plugin. How Does The Process Develop? Suspended Animation After the egg is laid the embryo stays in a kind of suspended animation until the hen sits on it to incubate it. October 26, Accessed April 03, Zadina, Chad, and Sheila E. October Accessed April 3, Become an Indiana Public Media supporter. The egg then rotates just before laying to be laid large end first, having moved through the oviduct small end first.
Adult hens need about 14 hours of daylight to lay eggs consistently and different lighting programs are used depending on the farming system, geographic location and season. The different farming systems include outdoor enclosures that use natural daylight and enclosed sheds that predominantly use artificial lighting programs. Most commercial farms use artificial lighting to some degree to get a consistent level of egg-laying all year round.
Eggs are produced using different methods with the three most common being free range , barn-laid , and cage. While each system has its advantages and disadvantages, the nutritional profile of the eggs is consistent across all systems. Learn more about these different farming systems today or take Australian Eggs' interactive tour of three commercial egg farms.
There are no roosters on commercial egg farms and hens lay only unfertilised eggs. Egg collectionOn commercial egg farms, eggs are collected at least once a day and taken to a high-tech room called a grading floor where they are cleaned and checked for quality. Have you ever stood in front of the egg section at the grocery store and felt overwhelmed? Egg labels can be confusing and although terms like 'farm fresh', 'barn-laid' and 'pasture-raised' are familiar to most egg buyers, many people don't know what they actually mean.
Demand for free range eggs has grown significantly in Australia over the last 15 years and egg farmers have responded by investing in increased free range egg farming capacity. Free range is now the most popular egg category at the supermarket, making up 47 percent of total retail sales.
Go to the home page Skip to navigation Skip to content Go to sitemap. How Do Chickens Make Eggs? What Are Free Range Eggs?
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