I have a sealed bottle of Martini Bianco from the seventies, stored for a long time. It has gradually developed sediments. Can you tell me whether it has gone bad or is it still good to drink?
Unfortunately, I believe that bottle is toast, kaput, dead. Or to paraphrase from the Monty Python “Dead Parrot” skit, that’s an ex-vermouth.
Your first clue is the sediment. Over time, the aromatic ingredients – herbs, spices and other botanicals – that were added as flavourings will precipitate out of solution into grainy particles that you’ll find floating around and even forming a crust on the glass. That separation will wreck the drink’s flavour balance.
But that’s not all. Vermouth is a wine, not a spirit, so its shelf life is limited because all wines eventually give in to oxidation, even when the bottle remains sealed. Unlike most wines, though, vermouth is fortified, meaning it contains an extra splash of alcohol. This will extend longevity slightly, but not by much. Martini Bianco contains 15-per-cent alcohol, which is not much higher than the base wine from which it was made. By contrast, a fortified port, which might contain 20 per cent, has a much better fighting chance against the clock.
Personally, I would not hold on to an unsealed white vermouth for more than about three years, though some people might opt for longer. Red vermouths, which tend to be much sweeter, generally will last longer because sugar partially masks the effects of oxidation.
This is not to say your wine will be unsafe to drink. Oxidation is mainly a flavour issue and not the same as the microbial action that can produce, say, botulism. If I were you, I simply wouldn’t mix up a martini with a 40-year-old vermouth, unless I wanted to reproduce the ambience of the dive bars of my youth.
Beppi Crosariol will once again be participating as The Globe’s wine expert on both the July 1-11, 2019, Globe and Mail Seine River (Paris and Normandy) Cruise and the July 28-Aug. 7, 2019, Globe and Mail Portugal River Cruise. For details on how to reserve your cabin visit GlobeandMailCruises.com.