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.
Milk could be considered both a heterogeneous and homogeneous  mixture, bit it depends on the type. Before milk is homogenized, it  is considered a heterogeneous mixture. Afâ¦ter homogenization, it is  considered a homogenous mixture.