What's the difference between Skim and Nonfat milk? And how do they skim the fat from whole milk?

By law, skim milk and nonfat are the same: containing less than 0.5 milkfat content. (The milk solids that are not fat must equal or exceed 8.25 percent.) In practice, all the fat possible is eliminated from the product. Any nonfat (or lowfat) milk that is shipped interstate must contain added vitamin A. Most of the vitamin A content in milk is contained in the milkfat. Most manufacturers add enough to equal the amount of vitamin found naturally in whole milk. How do they separate the fat from whole milk? Expert dairy consultans say, "It contains somewhere between 3 to 4 percent butterfat content. To obtain true skim milk, a machine called a "separator" is used. It whirls the milk around, and because the fluid and the butterfat content have different weights, centrifugal force separates the two ingredients into skim milk and cream.
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