Most recipes for a classic martini advise stirring with ice for about 30 seconds. To see if extra stirring was worth it, we made four martinis, adding 1 1/4 cups of ice, 3 ounces of gin, and 1 ounce of vermouth to each of four cocktail shakers. We then stirred the martinis for 15 seconds, 30 seconds, 1 minute, and 2 minutes, respectively.
When we took the temperature of each drink, we weren’t surprised to discover that the longer we stirred the colder the cocktail: The temperature of the drinks ranged from 40 degrees to 35 degrees. Since longer stirring causes more ice to melt, we also weren’t surprised that their volumes differed, ranging from 5 ounces in the drink stirred for 15 seconds to 6 ounces in the 2-minute cocktail.
What did startle us was just how different each martini tasted. Tasters found the martini that was stirred for 15 seconds to have not only a stronger alcohol flavor but also less noticeable aromatic herbal notes. The longer the drink was stirred the more pronounced these other flavors became.
Why does a colder, more dilute cocktail exhibit a broader spectrum of flavors and aromas? First, chilling makes the harsh-tasting ethanol less volatile and assertive, allowing more pleasant, subtle flavors to come through. Second, the ethanol in gin (and other spirits like scotch and whiskey) dissolves some of the water-insoluble aroma compounds. Diluting with water (from the ice) drives these molecules (and their aromas) out of the solution and into the air.
THE BOTTOM LINE
Cocktails like martinis require stirring with ice not just for lowering the temperature of the drink but also for the added water that the ice throws off as the drink cools. If you’re a fan of stiffer drinks that taste more of ethanol, by all means, stir for only 30 seconds. If you’d like a martini that’s more aromatic in flavor, be patient and keep stirring for a minute or two.