Milk, like wine, is a structured food, essentially an emulsion composed of tiny beads of butter surrounded by clear whey. You can’t filter it without altering its nature any more than you can strain a stew. Any attempt to force milk through a sterile filter has the effect of de-homogenizing it, separating out the cream. In wine, sterile filtration may also cause colloids to aggregate irreversibly into much larger ones that, lacking the surface area to integrate effectively, tend then to precipitate out.
