How Can You Tell If Maple Syrup Has Gone Bad?
Maple syrup seldom spoils if it’s kept sealed in a cool, dry location. The unopened maple syrup container has a decent shelf life. Mold and yeast growth can still occur in the syrup once the container is opened. Mold appears as dark patches, as well as yeast, which clouds the syrup and ferments it, leading to a sour smell. If you see the mold, or if the syrup has a sour smell or taste, it has gone bad and should be discarded.