Definition of substitution. 1  1a : the act, process, or result of substituting one thing for anotherb : replacement of one mathematical entity by another of equal value. 2  2 : one that is substituted for another.
Homogenized milk is any sort of milk that has been mechanically treated to ensure that it has a smooth, even consistency. The homogenization process typically involves high temperatures, agitation, and filtration, all aimed at breaking down milk's naturally occurring fat molecules.
The process of homogenizing of milk involves mixing the cream content into the milk itself. Where does the cream come from? Well, when you milk a cow the cream flows to the top. During the homogenization process, the fat from the cream is broken down so it is absorbed into the milk.