The Important Reason You Should Store Aperitifs In The Fridge
Aperitifs are the sometimes sweet, often botanical alcoholic liqueurs that you serve before dinner. They tend to be lower in alcohol content and are great on their own or mixed with some club soda. The lower alcohol content makes them great as an appetizer since no one has any food in them yet. But with as generic a definition as "drinks served before dinner," it's easy to get confused about what exactly the term encompasses.
For reference, popular aperitifs include Campari, both sweet and dry vermouth, Aperol, Lillet, and sherry. If you have any of these, or similar liqueurs, in a bottle at home, you should know that these are alcoholic beverages that need to be refrigerated. Although other types of alcohol can be safely stored at room temperature, the low alcohol content makes aperitifs more susceptible to decay. If you drink, say, old vermouth that hasn't been stored properly, you likely won't get sick but the flavors will have gone bad.
Aperitifs move past their prime through a process known as oxidation which starts to occur the moment the bottle is opened. An unopened aperitif is perfectly fine on the shelf – it's the contact with open air that starts the clock ticking. In case you were curious, it's the same process that causes wine to go bad.
The science of oxidation
Oxidation occurs because of the interaction of oxygen with various chemical compounds in the aperitif. Essentially, the process turns ethanol (read: alcohol) into acetaldehyde which has a unique, grassy taste. A higher alcohol content protects the drink from the oxidation process, which is why higher alcohol by volume (ABV) liquors such as whiskey and vodka don't feel the effects.
Typically, aperitifs range from 16% to 25% ABV. The lower the ABV, the faster the drink will oxidize — meaning the faster the flavor will flatten. Lillet, for example, is on the lower end of the spectrum, with an ABV of 17%. Unsurprisingly, it's also one of the aperitifs that goes bad the fastest. Even when placed in the refrigerator, Lillet will only last around three to four weeks once opened.
That's longer than a typical bottle of wine but shorter than other aperitifs. On the other end of the spectrum, we have Campari with an ABV of up to 28%. This is high enough that, when refrigerated, Campari can stay good for several years if properly sealed. Just don't forget to refrigerate these aperitifs once you open them because the lifespan of both will drastically decrease if stored at room temperature.