Does milk contain preservatives?

Chemical preservatives are not permitted in any milk products, said dairy researcher Steven Murphy. Some types of milk, such as sweetened condensed milk or canned milk concentrate of whole milk, contain natural sweeteners (usually sucrose) which help prevent spoilage, according to the National Dairy Council. Flavored milk  often contains stabilizers as well to prevent the chocolate from separating.
 
Sources:
Steven C. Murphy, Senior Extension Associate (Milk Quality Improvement Program)
Department of Food Science, Cornell University
National Dairy Council Factsheet: “Newer Knowledge of Dairy Foods--Protecting the Quality of Milk and Other Dairy Foods”