Why is milk homogenized?

When milk is whole, the cream naturally settles to the top. Homogenization is the process by which the cream and the milk are forcibly combined so that they don't separate when left standing. There are two reasons for milk producers to homogenize milk. For one, it ensures that the cream (what used to be the most valued part of the milk) is distributed evenly throughout so that every bottle has the same amount. Another, much less appetizing reason for homogenizing milk is directly related to pasteurization. Author Nina Planck describes it best: "After pasteurization, dead white blood cells and bacteria form a sludge that sinks to the bottom of the milk. Homogenization spreads this unsightly mass throughout the milk and makes it disappear."