What are the black spots that occurred on feta cheese in brine solution?

The black spots that occur on feta cheese in brine solution are most likely caused by the growth of mold. Mold is a type of fungus that can grow on food products, especially when they are stored in a moist environment. Feta cheese is a brined cheese, which means that it is stored in a saltwater solution. This creates the perfect environment for mold to grow, as the salt water provides the moisture that mold needs to thrive.

The mold that grows on feta cheese is usually harmless, but it can affect the taste and texture of the cheese. If you see black spots on your feta cheese, you can try to remove them by rinsing the cheese with clean water and then wiping it down with a paper towel. You can also store the cheese in a cooler, drier environment to prevent further mold growth.

If you are concerned about the safety of your feta cheese, you can always discard it and buy a new piece.