Does flavored milk have a longer shelf life than regular milk? If so, why?

Scientists are still determining this. Observation suggests that chocolate-flavored milk may spoil a few days earlier than regular milk as the flavoring appears to somehow stimulate the growth of bacteria, said Cornell University food science researcher Steven Murphy.  Some processors extend the shelf-life of flavored milk to 60-90 days, through ultra-pasteurization; the higher pasteurization temperature destroys more food-spoilage bacteria. There’s also the potential for reduced shelf life in flavored milk when processing is delayed at the plant due to prioritization of regular milk processing. Furthermore, food scientist Sussan Brewer points out, flavored milks usually contain additional thickeners and stabilizers to keep the flavorants dispersed, and these may make the products less stable and less easily pasteurized than regular milk.
 
Source(s):
Steven C. Murphy, Senior Extension Associate (Milk Quality Improvement Program)
Department of Food Science, Cornell University

Susan Brewer, Ph.D. University of Illinois, Department of Food Science and Human Nutrition

Dairy Management Inc. website: Innovate with Dairy.com--“Extending the Shelf Life of Chocolate Milk”