Milk is usually given what is called a flavor treatment to provide a product that is uniform in odor and taste.
During flavor treatment, milk is instantly heated to about 195 degree F (90.6 degree C) with live steam (injected directly into the product) after which it is subjected to a vacuum of about 10 in. (25.4 cm) in one chamber and to a vacuum of about 22 in. (55.9 cm) in another chamber.
The high vacuum treatment serves to regulate flavor, to cool the milk to about 150 degree F (65.6 degree C) and to evaporate water that may have been added through the injection of steam.While the milk is still hot, it is usually homogenized by passing it through a small orifice that breaks up the fat globules to a small size, preventing the separation of cream from the milk.
The milk is then quickly cooled to about 35 degree F (1.7 degree C). This is done by the same general procedure used in heating, except that refrigerated water or brine, or directly expanded ammonia is used in the coils, vat jacket, outer tubes of the pasteurizer.
During HTST (high temperature short time) pasteurization and during flavor treatment and homogenization, milk is passed through the heating and cooling cycles at such a rapid rate that at no time is it held for long periods at high temperature.
After processing and cooling, milk is filled mechanically into containers, made of waxed or plastic-coated cardboard of different volumes up to 2 qt and of semi-rigid plastic containers of 2 qt. or 1 gal and the containers are sealed.
In this state, milk should be held as close to 32 degree F as possible until consumed.
Milk Processing: Flavor Treatment
