I came across a question so simple that I’m stumped. Why is milk white?
Is it the casien?
PS… Chocolate milk doesn’t count wise-guys
c’mon guys, someone has to have an answer
Keep your shirt on. We are not here to drop everything and answer non-questions.
Casien in solution reflects white light. You knew this already.
Actually, I thought it was due, at least in part, to the milk fat. Phrased differently, blood with high levels of fat in it (similar to that found in milk) looks white, like milk. Here’s an example.
I’m sticking with the proteins, as fat-free milk is still white. Milk fats seem to be more yellowish.
DrFidelius and KarlGauss you’re both right.
FWIW bigbabysweets2000 finding this info. took approximately 2 seconds via google asking “Why is milk white?”. Before you ask the teeming millions next time try http://www.google.com first, it’s a great search tool. Welcome onboard.
dude… i tried… I already was pretty sure that the answer was casien, but I’ve found a lot of stupid stuff on the net before, so I figured I’d bring it to the big boy arena to settle this one out.
From:
http://www.uselessknowledge.com/explain/milk.shtml
I guess that’s not quite as stupid as the “why glass is clear” bullshit from howstuffworks.com, but it’s still wrong.
Fat molecules and casein molecules don’t reflect any significant amount of visible light. If you had a crystal of pure casein or a homogeneous sample of pure milk fat, it would be transparent.
Milk is white and opaque because it’s an emulsion, not a solution. Casein and fat in milk are present in the form of micelles that scatter light because they have a different refractive index from the water they’re suspended in. Every time a light ray passes from the water into a micelle or vice-versa, it gets bent a little because of the refractive index difference. The effect of having millions of micelles floating around is that every ray of light ends up going in a different direction because of being bent so many times. So when light hits milk it leaves the milk traveling in all different directions, making the milk look white. The same effect is what makes clouds and paint white, even though they’re made of clear substances.
But IIRC 2% is “whiter” than skim and whole milk is a little “whiter” than 2%. If fat levels are the main difference between these types of milk how can you say the percent of fat in the milk has no effect?
Did I say the percent has no effect? I don’t think I did. Of course the percent has an effect.
Yup, but that doesn’t mean that Bob’s wrong.
One interesting experiment to try at home is to mix milk and water. If you only add a litle milk to the water it looks bluish. That’s because the light gets scattered, and diferent wavelengths react differently. The shorter wavelengths (blue) scatter more easily, and the milk looks bluish. On the other hand the longer wavelengths (red) don’t scatter as easily and if you look at the transmitted light it will have a yellow/red hue.