The colour of milk is white due to the protein and fat molecules reflecting back light wavelengths; butter is yellow in colour due to the higher fat-content. The yellow pigment, called ‘beta carotene’, is found naturally in plants, which are eaten by cows. The pigment is carried over in the milk as fat. The fat globules in the milk are surrounded by a thin membrane, which hides the beta carotene in it. However, while making butter, the fat is churned; it breaks the membrane, allowing the fat globules to bind together and expose the beta carotene, thereby reflecting the colour yellow.
Why is butter yellow?
