substance that provides color of milk

Jim Mau elgusano at
Thu Aug 7 16:41:23 EST 1997

Hernan Espinoza wrote:
> tivol at (William Tivol) writes:
> >phg (pgueguen at wrote:
> >: hi
> >: i d like to know witch substance provide the white color of the milk?
> >: thank
> >       Comparing the color of skim milk to that of whole milk leads me
> >to conclude that the lipids contribute a lot to the color.  I guess that
> >casein is the major contributor to the color of skim milk.
>         I don't think so because the solutions of pure casein that I have
> are colored vaguely yellow.  It's not the lactose because 20% lactose is
> clear.
> I think your first guess about the lipids is right.  Skim milk still
> has a little fat in it.  (When does Fat-Free not mean fat free?  When
> the FDA says it can.)
> Anyone else?
>         -Hernan

	If I recall my freshman chemistry correctly,  Milk  is a "colloidal
suspension" of fat 'micells' (little round fat balls, i.e., the
'particles') in the liquid portion (i.e., the solvent).  The micells are
held in suspension due to equilibrium of electrical forces between
them.  Application of an electrical charge (+ or -, I don't recall which
nor may it matter) will cause the particles to lose this equilibrium and
all of the micells will 'drop' to the bottom of the reaction vessel due
to gravity.  Smoke, also a colloidal suspension, will do the same thing
in the reaction chamber and makes for a good demonstrations should you
need one for a science class. Perhaps Morrison & Boyd could explain
better.  doc

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