Why is milk white?
It’s a tough question, so here’s one of our experts to explain the answer.
Fonterra’s Principal Research Scientist, Sheelagh Hewitt, says it all comes down to how milk reflects light.
Milk mostly contains water, which, as we know is colourless. However, milk also contains protein, fat and vitamins.
One of the main types of proteins in milk are caseins, which join in small clusters with calcium and phosphate to form tiny particles called micelles.
When light hits the tiny micelle particles it causes the light to refract and scatter.
This causes milk to reflect all light wavelengths and absorb none, making it appear white.
But what if your milk doesn’t look pure white?
Not to worry, not all milk is perfectly white in colour.
That’s because milk fat globules can take on a yellow hue due to carotenoids, such as beta-carotene. The beta-carotene levels are higher in milk that is from grass-fed cows versus those who mainly eat hay or grains.
For more info on the nutritional benefits of grass-fed, read here.