I rolled by the liquor store this morning to do some post-holiday (or pre-holiday, depending on your viewpoint) restocking. So I walk up to the counter and say, "I need some triple sec, a small bottle of Jagermeister, and some creme de menthe. Now, for whatever reason, the guy behind the counter knew what triple sec was, knew what Jagermeister was, but hadn’t a clue what creme de menthe was. I lean over the counter and scan the liqueur section, and point out a bottle to him. “See that green bottle on the bottom shelf? Says ‘Menthe’ on it? $7.95? Nope, nope, to the left… the green one… yeah, that’s it!” OK, pitch it in the bag, pay for it, I’m done.
So I get home and pull out the bottles… and something’s kind of odd about the creme de menthe. It’s Marie Brizard brand creme de menthe. It’s kind of dusty and grungy. The label says, “1 Pint, 7.6 Fl. Oz”; no mention at all of metric measurement. And it’s got a tax stamp across the cap. At a guess, from the printing style, I’d say it’s 30-40 years old.
So first question: Does this stuff go bad? Or does it mellow with age? Or no difference? Did I get ripped off? Do different types of liquors react differently to age? If I go back to the same store for, say, scotch, do I need to be careful?
And second question: Can I tell just how old it is? By the tax stamp number? Any other way?
I know that Vermouth goes bad (and yellows) with age. It is basically a wine product, not a distilled liquor.
(Also, IINM, Vermouth is technically a brand name belonging to the Martini & Rossi company. But – like the name Champagne that once only was applied to sparkling wines from one region of France – it has become generic.)
Here is one thing I do know. In the mid 60s, Amex had a charity/contest. Basically, you sent in a sum of money that was given to the charity and the person who sent in the largest was to get any meal he wanted, no limit on price. Craig Claiborne, food critic for the NYTimes, won (and IIRC his bid was something like $300, which gives an idea of the inflation since). The meal he got was in a small restaurant in France that was not even ***. He had them arrange a meal for $4000 (think maybe $25,000 today). They opened three bottles of pre-phyloxera wine (so they had to be around 85 years old) before finding one that was drinkable. The other two were totally undrinkable. So wine cannot keep indefinitely. On the other hand, they opened one bottle of genuine Napolean brandy and that was fine (fine, fine) and more than 150 years old. So it would seem that 100 proof alcohol will last. Now I think that creme de menthe is more like 80 proof and I would expect that to last.
If the proof is high enough, the liquor will not spoil. I’d say 30-40% would be enough to act as a preservative. Liqueurs, OTOH, will thicken as the alcohol evaporates if it’s not sealed properly.
Once the stuff (gin, creme de whatever, scotch) hits a properly sealed bottle, and is stored at the proper temperature out of sunlight, it stops changing. Scotch that’s labelled as 16-year old has spent 16 years sitting in wood barrels, where some of it evaporates as it goes across the porous wood, getting flavor and mellowing as the volatile alcohol evaporates.
Once it’s in the bottle, it’s not going to get better or worse. It’s stopped aging (except for slight residual oxidation), and it’s going to taste the same if you drink it the day you bought it or if you wait ten years.
I say crack her open and take a swig. If anything, it may be a little thick, which can be solved by adding vodka until the desired consistency is achieved.
If it is properly sealed it can last indefinitely, corking, sealing, and sterile packaging technology today is a little more advanced than it was then. A little crack or microscopic hole in a cork and 85 years can easily spoil a bottle of wine. If you are looking to save part of a batch that long you would take extra precautions like using highest grade corks and dipping the tips of the bottles in wax or plastic to seal them totally airtight.
Sugars in solution can epimerize (turn into other sugars) over a long period of time. This can alter the taste of even high proof liquors. Metal ions, or a high pH speed up the process. There doesn’t seem to be a good reference for this online.
It can also depend on what’s in the liqueur. Creme de Menthe (despite the name) contain’s no cream. Bailey’s, on the other hand, does. So a bottle of Bailey’s would be more “fragile” over time than a bottle of Creme de Menthe - and especially after it has been opened.