The milk is heated between 104 and 162 F (40 and 72 C.) It reduces bacterial counts in the milk, but isn’t enough to eliminate all bacteria. It also leaves alive enzymes in milk, which cheesemakers ideally want to preserve.
The American Food and Drug Administration (FDA) regards thermalized milk as unpasteurized, and still requires cheeses made with it to be aged for the standard 60 days that unpasteurized milk cheeses must be aged for.
While it’s not enough pasteurization for the FDA, cheese purists object to the cheeses made from it being called unpasteurized milk cheeses. They say some good bacteria are also killed off, affecting the taste of the cheese. They maintain that any temperature above the body temperature of the cow is detrimental.
In Quebec, cheese made from thermalized milk can be labelled either as being made from unpasteurized milk or pasteurized milk (cf. Chevre Noir.)
Some cheeses in France that are supposed to be made with raw milk according to their AOC designation raws are made with thermalized milk.
Some people also use the term “thermalization” to mean “reheating.”