What is the primary colorant used to color cheese?

There is no single primary colorant used to color cheese. The color of cheese is primarily determined by the presence of beta-carotene, a pigment found in animal feed.

Here's a breakdown:

* Naturally yellow cheese: Cows that eat alfalfa and other green forage high in beta-carotene produce milk with a natural yellowish hue, resulting in yellow cheese.

* Artificial coloring: In some cases, annatto, a natural dye derived from the achiote seed, is added to cheese for a more vibrant yellow color. This is particularly common in cheddar cheese, especially in the US.

* White cheese: Cheeses made from milk of cows that eat mostly hay or grain have a lower beta-carotene content, resulting in a whiter cheese. Examples include mozzarella and ricotta.

So, while there's no single primary colorant, beta-carotene is the key factor that contributes to the yellowness of many cheese varieties.