Royalty-free photo courtesy of PickPik
Easter egg basket
Is there an Easter egg hunt in your near future? Are you dying eggs for the Easter basket? MedStar Health's Dr. Kelly Johnson-Arbor answers questions here about egg safety. She serves as the medical director of Hyperbaric Medicine in the Center for Wound Healing and Hyperbaric Medicine. An expert in the fields of Emergency Medicine, Medical Toxicology and Hyperbaric Medicine, she is an Associate Faculty member at the MedStar Institute of Quality and Safety and contributing author to the website of the MedStar Institute for Bloodless Medicine and Surgery, medstarbloodless.org. Here's her advice.
Why is Salmonella a concern when it comes to eggs?
Salmonella is a bacterial infection that is a common cause of food poisoning. Salmonella causes around 1.2 million illnesses in the United States every year. Common signs and symptoms of Salmonella infection include abdominal pain, vomiting, and diarrhea; most people with Salmonella gastroenteritis recover within a week, but some people may develop more serious infections.
Eggs are the food most commonly implicated in Salmonella outbreaks, followed by chicken, pork, and beef. Chicken and hens infected by Salmonella are typically asymptomatic but can lay eggs that contain the bacteria. In addition, Salmonella can pass through pores or tiny cracks in freshly hatched eggshells, resulting in egg contamination. Consuming raw or undercooked eggs is a risk factor for developing Salmonella infection, but contaminated eggshells can also transmit Salmonella and other bacteria.
Do eggs need to be washed once they are brought home from the store?
In the United States, Australia, and Japan, table eggs are thoroughly washed prior to being sold in grocery stores, so they do not need to be washed again after they are purchased. The egg washing process removes debris, including bacteria, from eggshells, and also improves the visual appearance of the eggs. Chlorine and quaternary ammonia cleansers are typically used for commercial egg washing processes, and eggs are refrigerated after washing to prevent additional bacterial growth.
While the egg washing process facilitates removal of bacteria from the eggshell surface, it also damages the cuticle of the egg. The cuticle is an invisible layer of protein that covers the eggshell surface and prevents transfer of water and fluids through the eggshell pores. When the cuticle is damaged, bacteria can penetrate the eggshell more easily through the pores, potentially contaminating the egg. However, commercial egg washing processes remove bacteria from the eggshell, making cuticle damage less of a concern.
Why are eggs sold in other countries not refrigerated?
In countries where eggs are not washed prior to being sold, the cuticle remains in place and provides a barrier to transfer of Salmonella and other bacteria through the eggshell. Since the intact cuticle provides a natural barrier to infectious organisms, there is a lesser risk of Salmonella contamination, even when the eggs are stored at room temperature. Because of this, refrigeration is not required. In the European Union, egg washing is prohibited, and washed eggs are downgraded to a lower egg quality, given the concerns associated with cuticle disruption.
How long can hard boiled eggs be left out?
Hard boiled eggs should be refrigerated within two hours of cooking, to limit bacterial growth.
Why do boiled eggs go bad faster than raw eggs?
The hard-boiling process causes a small amount of water to transfer through the eggshell and onto the cooked egg white surface. The presence of water on the eggs’ surface creates an environment where bacteria can grow, which can lead to faster spoilage. Because of this, the USDA recommends that hard-boiled eggs be consumed within a week (in contrast, raw eggs often don’t expire for several weeks after they are packaged).
Why are some eggs harder to peel than others?
Fresher eggs are often harder to peel than older eggs, due to changes in the pH of the egg white that occurs over time. Over time, carbon dioxide and moisture escape through eggshell pores, and this causes a change in the consistency of the egg white. Over time, the pH of the egg white also increases, and these changes makes the eggs easier to peel after being hard-boiled.
What are egg dyes made from?
Common egg dyes that are available for purchase at retail stores contain synthetic food dyes, including FD&C Yellow #5, FD&C Red #40, and FD&C Red #3, in addition to stabilizers like maltodextrin. People can also make their own natural egg dyes from beets, purple cabbage, blueberries, or red onion peels.
Are egg dyes toxic?
Commercially available egg dyes, like Easter egg dye tablets, are unlikely to cause serious harm if swallowed. Nausea, vomiting, and stomach upset are common symptoms that may occur after consumption of food dyes, including egg dyes. Some food dyes can cause allergic reactions, so people who are susceptible to such allergies may want to avoid using synthetic egg dye products. Although some synthetic food dyes have been linked to cancer, ADHD, and other health disorders, such associations are controversial and in need of additional research. Overall, consumption of dyed eggs or even the dyes themselves is likely to be safe for most individuals.
What happens if you eat egg dye?
Consumption of synthetic food dyes may result in gastrointestinal upset, nausea, or vomiting. However, these symptoms are likely to be self-limited and should resolve on their own.
Photo courtesy of MedStar Health
Dr. Kelly Johnson-Arbor, toxicologist with MedStar Health.
About the author: Dr. Kelly Johnson-Arbor serves as the medical director of Hyperbaric Medicine in the Center for Wound Healing and Hyperbaric Medicine. An expert in the fields of Emergency Medicine, Medical Toxicology and Hyperbaric Medicine, she is an Associate Faculty member at the MedStar Institute of Quality and Safety and contributing author to the website of the MedStar Institute for Bloodless Medicine and Surgery, medstarbloodless.org. Dr. Johnson-Arbor has published and presented on a variety of topics and serves as a reviewer for multiple peer-reviewed journals. She received her medical degree from Loyola University Stritch School of Medicine, completed a residency at University of Rochester Medical Center and a fellowship at the University of Connecticut Health Center. She is board certified in Emergency Medicine, Medical Toxicology, and Undersea and Hyperbaric Medicine.
