The egg yolk is black

Under normal circumstances, the yolk of an egg is yellow. If the yolk of an egg turns black, it is generally a chemical change. At this time, the yolk and iron elements change to form iron sulfide, which will reduce the nutritional value of the egg and easily form indigestible substances. It is not good for gastrointestinal conditioning. Therefore, when the egg yolk turns black, it is best not to eat it.

Black egg yolk

The black color should be iron sulfide.

If eggs are cooked in boiling water for too long (more than 10 minutes), a series of chemical changes will occur inside the egg. For example, the protein in eggs contains more methionine. After being heated for a long time, methionine can decompose into sulfide, which reacts with the iron in the yolk to form green or gray-green iron sulfide around the yolk. Iron sulfide is not easily absorbed and utilized by the human body, thereby reducing the nutritional value of eggs. After eggs are cooked for a long time, the protein structure becomes tighter and is not easy to come into contact with the protein digestive enzymes in the gastric juice, so it is more difficult to digest.

Can I eat egg yolks that turn black?

Eggs that are black inside cannot be eaten because they have gone bad.

There are many ways to eat eggs. In terms of nutrient absorption and digestibility, boiled eggs are 100%, scrambled eggs are 97%, tender-fried eggs are 98%, deep-fried eggs are 81.1%, eggs mixed with boiling water or milk are 92.5%, and eaten raw are 30% to 50%. Therefore, boiled eggs are the best way to eat them, but you should chew them slowly, otherwise it will affect absorption and digestion. However, for children, steamed egg custard and egg drop soup are the most suitable, because these two methods can loosen the protein and are easily digested and absorbed by children.

How to eat egg yolk

1. Stir-fry with egg yolk: mash the cooked egg yolk and use it to stir-fry vegetables, such as lettuce and rapeseed. Add a little oyster sauce and it tastes really good.

2. Cold salad: Mix cooked egg yolk with shredded jellyfish, kelp and cucumber. It is delicious and you don’t have to worry about high cholesterol.

3. Cook porridge: This is my favorite. Cook the porridge first, then cut the cooked egg yolks and preserved eggs into small pieces and put them in the porridge pot and cook for about 5 minutes. Add some salt to taste. The thick porridge with the aroma of eggs is a summer delicacy.