Why Cheese Is Yellow Instead of White Like Milk

Edward Vega of Vox spoke with Paul Kindstedt, a Food Science Professor at the University of Vermont and former president of the American Dairy Science Association, to learn more about what actually makes cheese varying shades of yellow instead of white like milk.

Why is cheese often yellow even though milk is white? Of course, this isn’t entirely true across the (cheese)board — cheese comes in a remarkable range of colors, from pale white to deep yellow-orange. Take cheddar, for instance — it can be found in both shades. So which color is the “real” cheese?

It turns out that after moving from sheep to cows in the 15th century, farmers noticed that the cheese they made from cow’s milk was yellow in color. This was due to the beta-carotene in fresh grass. When the cows ate the grass, the beta-carotene was processed as milk fat, which is used in butter and cheesemaking.

Grass, when it’s lush, and green, and in season, contains beta carotene. When sheep process the beta carotene in grass, It doesn’t make its way into the milk. Therefore, sheep cheese is pretty much always naturally white. In the cow it’s a different metabolic pathway. Beta carotene, goes into the cow, passes into the milk, is part of the fat in milk and then gets concentrated in the cheese and that’s what gives cows milk, cheese its yellow color.

During the summer, it was very easy to sell yellow cheese and butter, however during the winter months, cheesemongers relied on natural dyes such as saffron, marigold, or carrot juice but these were expensive. When annatto seeds from the achiote tree became available in Europe and the New World, sellers used the seed’s intense color to dye cheese. This practice continues through modern day.

So the coloring was for marketing and this then becomes the tradition, over centuries …With factory farming, cows aren’t as grass fed as they used to be. diets tend to include a lot more corn and soy. But because we’ve been used to centuries of saturated colors of cheese, none of that really matters when it comes to marketing. We still expect our cheddar to maintain a golden hue, and we can still think annatto for that.