|Why is milk white?
|Question Date: 2001-02-13|
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.
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.
All milk is white but the shades of white will
vary depending upon the composition or what is
dissolved in the milk. The most important factors
that contribute to the color of milk are fat, how
much cassein there is(one of the classes of milk
proteins) and what calcium complexes (these are
minerals), and how much water-soluble riboflavin
(a vitamin). These compounds contribute to milk's
opaque or ivory color by interfering with light
So why is milk white and not
green for example? Because there are so many fat
and protein molecules in milk that enough light at
all wavelengths gets scattered giving the
appearance of white light. If all the wavelength
of the light would get absorbed, milk would be
The color also depends on what the cow
eats. If there is a lot of carotene in the diet it
will also affect the color. They provide a
yellowish color. High concentrations of riboflavin
also contribute to the yellow color. Removal of
the fat and therfore carotenoid pigments and
solids when making skim milk makes the milk look
NEAT question. Do you have any guesses? Why is
raspberry juice red? Well, something in the
raspberry gives it the red color, and when you
make juice from raspberries the red stuff goes
into the juice too, right? Milk is white, right?
Well, milk is white because there is something in
the milk that makes it white. There are proteins,
fats and carbohydrates (a big word for types of
sugar). All of these make the milk look
For scientists and future
scientists, there is a more complicated answer.
Milk is white because there are so many fat and
protein molecules in milk that enough light at all
wavelengths gets scattered giving the appearance
of white light. Maybe you will want
Scienceline another question about light
scattering, or maybe you will want to ask a
friend, teacher or parent to explain it. Anyway,
it doesn't change the fact that milk is tasty,
I don't know exactly why milk is white. In
general, though, the color of something depends on
what colors it reflects versus what colors it
absorbs or transmits. So, if you have "white"
light (all colors of the rainbow) shining on, say,
lemonade then yellow light is getting reflected to
your eyes while other colors are being absorbed by
the lemonade. If you can see through the
lemonade, then some of the light is also being
transmitted through. You usually can't see
through milk so very little light is getting
transmitted. The light that get reflected
looks white. The rest is adsorbed.
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