How Do You Know If Vermouth Has Gone Bad?
Vermouth may go bad once it’s open and exposed to air. It can spoil partly due to oxidation and partly due to the expiration of its ingredients. Vermouth can go stale and lose its flavors and aromas once oxidized. Some common signs of bad vermouth include a change in color, a change in aroma, and a sour or stale taste. It is recommended to store the vermouth in a cool place and use a wine preserving tool or consume it within six months of opening.