The shelf life of Duncan Hines frosting typically varies based on the type of frosting and storage conditions. Unopened, canned frostings can last for up to twelve to eighteen months past the best by date when stored in a cool, dry place. However, it is essential to check the packaging for specific expiration dates as they may vary by product. Once opened, it is advisable to refrigerate any unused frosting and consume it within two to four weeks for the best quality and flavor. Always inspect the frosting for any signs of spoilage, such as off smells or discoloration, before use. For the most accurate information, it is helpful to refer to the current web page for Duncan Hines products, where one can find further details regarding shelf life and storage recommendations.