Milk and butter can come from the same cow on the same day, yet one is white and the other is often yellow.

The difference begins with a plant pigment called beta-carotene, the same compound that gives carrots and pumpkins their orange color.

When cows eat grass and other plants, some of that beta-carotene is absorbed into their milk fat. But in milk, the amount is so diluted that you rarely notice it. Milk also contains billions of tiny fat droplets and protein particles that scatter light in all directions, making the liquid appear white.

Butter tells a different story.

Making butter concentrates the milk fat and removes much of the water. As the fat becomes concentrated, so does the beta-carotene dissolved within it. The yellow pigment that was nearly invisible in milk suddenly becomes much easier to see.

That's why butter from pasture-raised cows is often a rich golden color, especially during spring and summer when fresh grass is abundant. Butter produced during winter is often much paler.

In a sense, the color of butter is a record of a cow's diet. The golden hue began as sunlight captured by plants, passed into the grass, then into the cow, and finally into the butter on your table.