The White String You Can See In Raw Egg Yolks Has A Name
By Linda Larsen
By this point, you have probably cracked hundreds, if not thousands, of eggs in the kitchen and wondered what that little string near the yolk is. For one, it is not a mini embryo, chicken sperm, or an umbilical cord, but this little string in the egg indicates that it is fresh.
A chalaza (chalazae is the plural), according to Science Direct, is a film that covers the entire yolk, and the fibers at both ends wind up as it turns around in the hen's uterus, giving the structure its signature ropy appearance. It is made of protein, is completely safe to eat when cooked, and holds the yolk inside the egg white to protect it from bumping up against the shell.
Removing the chalaza depends on how the egg is cooked — it usually disappears when cooking scrambled eggs, and removing it when separating the yolk from the white will break the yolk, leading to a meringue fail. For perfect custards, it is best to remove the chalaza with a fork or chopsticks, or you can strain the custard after it's cooked before you cool it.