With boiled eggs, the yolk can get a blue/green tint, particularly when over-cooked or cooked at too high a temp a reaction most of us have seen. It is a reaction between sulfur and iron. The same can occur with scrambled eggs. Over cooking and cooking at high temperature is considered a prime culprit.
Chickens that lay blue eggs have the pigment oocyanin added to them all the way through the shell-making process so the eggs are blue both inside and outside. Chickens that lay white eggs have no pigment added. Research has found that having colored eggs can be an advantage in some cases.
According to FoodSafety.gov, when you boil an egg for too long, sulfur and iron compounds react on the surface of the yolk, creating this icky color. Or, this might happen if there's a high iron content in your cooking water. But, that's it. This is safe to eat.
And not necessarily harmful; blue eggs are widely eaten and the Araucana, in particular, is a very popular exotic chicken breed.
No Green Film Around the Yolk
If you cook a hard-boiled egg too long, a blueish-greenish film will coat the outside of the yolk, caused by a chemical reaction between naturally occurring sulfur and hydrogen in the egg. It's not harmful to eat but doesn't look or taste great.
The ring is caused by a chemical reaction involving sulfur (from the egg white) and iron (from the egg yolk), which naturally react to form ferrous sulfide at the surface of the yolk. The reaction is usually caused by overcooking, but can also be caused by a high amount of iron in the cooking water.
The green ring is harmless and safe to eat. To avoid green eggs, hard-cook instead of hard-boiling eggs: Place eggs in a single layer in saucepan. Add cold tap water and cover by at least 1 inch above the eggs.
The best thing you can do is respect the Migratory Bird Treaty Act and leave the egg alone. In most cases, it is unlikely the egg would hatch. If you know the egg is from a rare or endangered species, call your state fish and wildlife agency or a wildlife rehabilitator.
Off-color egg white, green or iridescent – Spoilage due to Pseudomonas bacteria, a very common type of bacteria that healthy people often carry without knowing it. This bacteria produces a greenish, fluorescent, water-soluble pigment in the egg white. If you come across an egg with an off-color egg white, discard it.
Blue coloured eggs are starting to become more common as backyard breeders look for variety with breeds such as araucana and ameraucanas. While a blue egg layer will never lay a brown egg, crossbreeding of chickens can bring out a range of eggshell colours.
The color of the yolk will change based on the diet of the hen who laid it, so the shade of yellow or orange nothing to do with freshness. Instead, inspect the egg white, or albumen. If it is pink, green, or iridescent, the egg has been contaminated by Pseudomonas bacteria and is not safe to eat.
One of the most popular questions we get asked by visitors to our farm is about the color of our eggs: Do the different colors have a different taste? The short answer is no. While the eggs look different on the outside, their inside is all the same.
Some believe that brown, green, blue, or pink eggs are healthier than white chicken eggs. The truth is, there is no nutritional difference between colorful chicken eggs and white chicken eggs. If you've ever wondered why chicken eggs come in a variety of colors, the reason has to do with genetics.
Why Eggs Are Blue? The bile pigment biliverdin is responsible for blue tones in bird eggs, including robin's eggs. The color of an eggshell is determined by these pigments as they are deposited as the shell is formed in the shell gland.
To check the state of an egg, crack it onto a plate and look carefully at the colour and thickness of the white and yolk. A fresh egg should have a bright yellow or orange yolk and a thickish white that doesn't spread too far. If it's off, the yolk will be flatter and discoloured and the egg white will be far runnier.
The frequency of Salmonella-contaminated eggs in Australia is very low. Despite this, there is a potential risk of illness from consumption of raw or lightly-cooked eggs, or the consumption of uncooked foods containing raw egg.
As long as you use food-safe dyes or food coloring in your decorating, the coloring itself will pose no health risks. If you are treating your dyed eggs just like normal hard-boiled eggs, putting them in the fridge after dyeing and then using them for egg salad, you're good to go.
Only keep raw egg dishes for one day and refrigerate at all times. Time spent at room temperature is bacteria's best friend. Wash your hands with soap and water after handling uncooked eggs so there is no risk of transferring bacteria from the eggshell surface to other foods in the kitchen.
The best kept secret in determining an egg's freshness is to see if it sinks in water. To try the egg water test, simply fill a glass or bowl with cold water and submerge the eggs. If the eggs sink to the bottom and lay flat on their side, they're still fresh.
The Araucana chicken from Chile and the Dongxiang and Lushi chickens from China (none of which are particularly common in North America) are known to lay pale-blue eggs. This is rare for a chicken; while bird eggs can come in all sorts of colors and patterns, chicken eggs are almost always white or brown.
First, fill a bowl or glass with about four inches of cold water and gently place your egg(s) inside. Very fresh eggs will sink to the bottom and lay on their sides. If an egg stays at the bottom but stands on its small end, it's still acceptable to eat; just not quite as fresh.
The greenish coating around the yolks of hard-cooked eggs results from cooking at too high a temperature or too long a time or from not cooling the eggs rapidly following cooking.
What is this? Blue eggs generally will cost more because blue egg laying breeds are not only not as consistent layers as the leghorn, for example, that lays white eggs, but also because those breeds are larger and need to eat more feed in order to produce their eggs.