Why Is Milk White?

[dappynappy]

As above, thanks.

[netibiza]

Why does a red cow give white milk, when it only eats green grass!!

[jomifl]

Because the droplets of fat and protein in suspension reflect light.

[dappynappy]

Thank you jomifl.

[alavahalf]

But surely if you milked a cow in a dark with the lights out ... wouldn't the milk still be white ... or would it be black ..?

[Retrochic]

ALAVAHALF -it would be blue -seriously -but only until you turned the lights on.

[alavahalf]

I get it now ... I am often asked when I am given a coffee ...


......Black or White Sir ....?

[weecalf]

milk is not white enough thats why they use paint in some adverts to make it appear white, so it sorta offish white .

[Old_Geezer]

Because it's not blue.

Actually not all milk is white, yak's milk is pink (i believe because it has blood in it).

[dappynappy]

Really? Yuck.

[mariostewart62]

Milk is white because of its reflectance properties. The reason anything is white is that it reflects all wavelengths of light and absorbs none, therefore it is white. If milk were black, that would mean it absorbs all wavelengths of light and reflects none. The reason a shirt is blue is that all wavelengths of light are absorbed except for blue, which is reflected.
Light can have other properties as well. For instance, the reason that asphalt on the road gets hot is because it's black and absorbs almost all energy from the sun and reflects almost none. White things, like roofs, tend to reflect wavelengths of light and therefore keep the house cooler.