As an expert sommelier and brewer, I can assure you that sweet vermouth does have a shelf life. While it won't necessarily go bad in the sense of becoming harmful to consume, its quality and flavor will deteriorate over time. It's important to store your sweet vermouth properly to ensure it stays fresh for as long as possible.
Once you open a bottle of sweet vermouth, it is crucial to keep it in the refrigerator. This helps to slow down oxidation, which is the main factor that causes the flavor to degrade. Oxidation occurs when the vermouth comes into contact with air, and it can lead to a loss of freshness and complexity.
Ideally, you should aim to consume your opened sweet vermouth within a month. This is when it will be at its best, showcasing its vibrant flavors and aromas. After the first month, the quality will start to decline gradually. However, it's worth noting that even after a month, the vermouth will still be drinkable and enjoyable, just not as vibrant as when it was first opened.
If you find yourself with a partially consumed bottle of sweet vermouth that you won't be able to finish within a month, there are a few options. Firstly, you could consider inviting some friends over to share it with you. Vermouth can be a fantastic base for cocktails or enjoyed on its own, so a small gathering could be a great way to make use of it.
Another option is to give the vermouth away as a gift. If you have a friend or family member who enjoys cocktails or appreciates fine spirits, they might be delighted to receive a bottle of sweet vermouth. It's a thoughtful gesture and ensures that the vermouth doesn't go to waste.
In terms of timeline, you can expect your sweet vermouth to remain in passable shape for about two months after opening. During this time, it will still be drinkable, although you may notice a slight decline in flavor and aroma. After the two-month mark, the vermouth will likely have lost much of its original character and may taste flat or stale.
To summarize, storing your opened sweet vermouth in the refrigerator is crucial to prolong its freshness. Aim to consume it within a month for the best experience, but don't worry if you can't finish it that quickly. You can still enjoy it for up to two months, albeit with a slight decline in quality. If you find yourself with an excess amount of vermouth, consider sharing it with friends or giving it away as a thoughtful gift. Cheers!