pasteurization rules are usually set by national food safety agencies (like the usda in the united states and the food standards agency in the united kingdom). these agencies say milk has to be htst pasteurized to have the "pasteurized" label. there are different rules for different dairy products, depending on the fat content and what they will be used for. for example, the pasteurization rules for cream are different than the rules for fluid milk, and the standards for pasteurizing cheese are designed to keep the phosphatase enzyme fresh, which helps in making the cheese.