Eggs are close to being a perfect food. Egg yolks deliver vitamins A, D, E, K and B12, omega-3 fats, folate and antioxidants. They are also versatile. You can use them at any meal, kids love them and they can be cooked inside or outside the shell.
Until the 1920s, chickens were raised almost exclusively for their ability to lay eggs. The meat was seasonally available, expensive and not very tasty.1 This changed, quite by accident, in 1923 when farm wife Cecile Steele mistakenly ordered 500 hatchlings instead of 50. The farmer sold the extra chickens for meat. The "mistake" was so successful, she repeated it in the following years. Then, in 1948 a contest was sponsored to breed a better tasting chicken and today Americans eat more chicken than they did in the early 20th century.2
In the 1960s, as the low-fat fad gained momentum, doctors recommended eating just the whites of eggs as the yolks were reportedly high in cholesterol, which was mistakenly thought to be bad for your health. Media warned eggs increased your cholesterol level and your risk of heart disease.
Today, following the recommendations of researchers and scientists, the egg is recognized as a nutritious food and the U.S. Government Office of Disease Prevention and Heath Promotion's Dietary Guidelines for Americans3 2015-2020 has dropped their strict limits on dietary cholesterol.4 Although eggs offer significant nutritional benefits, it is vital to seek out high quality eggs and protect your health from cooking methods that may trigger significant burns or create toxins in your food.5
Superheating in a Microwave Is Explosive
Hard-boiled eggs, reheated in a microwave, are an accident waiting to happen. A 9-year-old girl in the U.K. found that out when she reheated an egg for 40 seconds, and while carrying the egg to a table, the egg exploded.6 Pieces from the superheated egg tore her cornea and required a lens replacement to restore her vision months later.
Ophthalmologists used this as a case study when they made an appeal to microwave manufacturers to place warning labels on microwave ovens about the dangers of exploding eggs.7 Manufacturers warn against microwaving eggs without first piercing them several times. But those warnings are found in leaflets that accompany the microwave, which many owners toss, explains Dr. Saurabh Goyal, ophthalmologist at Queen Mary's Hospital in the U.K and one of the letter's authors.8
It is not just eggs that explode in the microwave. An Illinois woman scalded her face and corneas after a bowl of water she heated in the microwave exploded in her face.9 Louis Bloomfield, Ph.D., a University of Virginia physicist explained to ABC News:
"You're used to having water or liquid boil when you heat it above a certain temperature, but there are occasions, and they're more frequent than you'd expect, in a microwave oven when the water goes to or above boiling without any bubbles forming. And that's a phenomenon known as superheating. Well, it's almost like a bomb once you've got it superheated adequately, because anything that triggers the boiling, once you've reached that temperature, will cause catastrophic, very sudden flash boiling."
A review of the literature published in 2001 found 13 cases where individuals were burned by exploding eggs after they were removed from a microwave oven.10 In some of those cases the explosion occurred even after the shell or yolk had been pierced. In 2002, an estimated 2,700 people in the U.K. sustained a microwave-related injury, half of those from hot liquid. More recently, a lawsuit was filed after a customer at a restaurant bit into an egg that had been reheated in a microwave. The egg exploded in his mouth with a loud bang, causing burns.
Exploding Eggs Do Not Cause Acoustical Damage
During the ensuing court case, a San Francisco-based firm specializing in acoustics was asked to determine if the noise from the exploding egg could have caused hearing damage.11 The firm presented their results during the 174 Meeting of the Acoustical Society of America.
During the experiments, the scientists controlled variables, including measurement of sound levels, internal temperature of the eggs and documentation of the different kinds and sizes of the eggs used.12 hard-boiled eggs were put into a water bath and heated for three minutes in the microwave. The temperature of the water bath was measured in the middle and end of the heating time.
The eggs were then removed from the water bath, placed on the floor and pierced with a fast-acting meat thermometer to both pierce the egg and measure the internal temperature of the yolk. The researchers found the internal temperature was consistently higher than the water bath from which the eggs had been removed. This suggested to the researchers that the egg was more receptive to heating from the microwave than was the surrounding water. The scientists hypothesized:13
"... that the egg's protein matrix traps small pockets of water within the yolk, causing the pockets to superheat well above the nominal boiling temperature of ordinary tap water. When these superheated pockets are disturbed by a penetrating device, or if one attempts to bite into the egg yolk, the water pockets all boil in a furious chain reaction leading to an explosion-like phenomenon."
The team was tasked to answer the question of whether an exploding egg created enough pressure to damage hearing. They found that, although loud, a single explosion wasn't enough to damage hearing. Anthony Nash, currently serving on a U.S. Technical Advisory Group to review and comment on international standards addressing mechanical vibration in the environment, explains their results:
"We needed to quantify the peak sound pressures from an exploding egg so we could compare it to hearing damage risk criteria. At 1 foot away, the peak sound pressure levels from microwaved eggs covered a wide range from 86 up to 133 decibels.
Only 30 percent of the tested eggs survived the microwave heating cycle and exploded when pierced by a sharp object. On a statistical basis, the likelihood of an egg exploding and damaging someone's hearing is quite remote. It's a little bit like playing egg roulette."