我们熟悉的“乳白色”来自于牛奶。那么牛奶为什么会是白色的呢？这主要是因为牛奶中的蛋白质——干酪素。
 
Those chalky-white mustaches that color our lips after chuggingdown a refreshing¹ ice-cold glass of creamy milk is caused by the protein called Casein.
Rich in calcium², Casein helps contribute to milk's white color.

In addition, the cream that is found in milk contains white colored fat. The more cream in milk the more white it is.

Low and non-fat milk appear more grayish rather than white because they contain less cream.

Another reason milk looks white to our naked eyes is because some objects do not absorb very much light. Rather than absorb light, these objects reflect light. For instance, red colored objects reflect only red light and absorb the other colors of light in the rainbow spectrum³. The molecules⁴ that make up Casein and cream reflect light. That's why milk is white.

mustaches: 胡子

Casein:干酪素

calcium:钙

non-fat milk:脱脂牛奶

spectrum:光谱

molecules:分子