Also, after milk is homogenized, it becomes more vulnerable to spoilage from exposure to light and heat. Before milk is homogenized, it must be pasteurized because if fresh milk were homogenized ...

While it is possible to have pasteurized milk that hasn't been homogenized and homogenized milk that hasn't been pasteurized, most milk found in U.S. supermarkets have undergone both processes.

First introduced in 1932, homogenized milk came to dominate the market by 1965. More significantly, homogenization extended shelf life so milk could be kept for more than three days.