What does it mean when meat turns blue?

When meat turns blue, it is a sign of spoilage. This can be caused by a number of factors, including:

* Myoglobin: Myoglobin is a protein that gives meat its red color. When meat is exposed to oxygen, myoglobin oxidizes and turns brown. However, if meat is not exposed to oxygen, myoglobin can also react with other compounds to form a blue pigment called metmyoglobin.

* Nitrites: Nitrites are chemicals that are often added to meat to prevent spoilage. However, nitrites can also react with myoglobin to form a blue pigment called nitrosomyoglobin.

* Hydrogen sulfide: Hydrogen sulfide is a gas that is produced by bacteria. When meat is contaminated with bacteria, hydrogen sulfide can react with myoglobin to form a blue pigment called sulfmyoglobin.

Meat that has turned blue should not be eaten. This is because the meat may contain harmful bacteria that can cause foodborne illness.