De acordo com alguns, arejar o gim, espalhando-o ao redor altera o sabor, ou "contusões"; ou mais perceptivelmente, é provável que rapidamente notemos que as pequenas bolhas perturbam sua textura normal de língua / palato.
Da Wikipedia, " Abalado, não mexido ":
Some connoisseurs believe that shaking gin is a faux pas, supposedly because the shaking "bruises" the gin (a term referring to a slight bitter taste that can allegedly occur when gin is shaken). In Fleming's novel Casino Royale, it is stated that Bond "watched as the deep glass became frosted with the pale golden drink, slightly aerated by the bruising of the shaker," suggesting that Bond was requesting it shaken because of the vodka it contained. Prior to the 1960s, vodka was, for the most part, refined from potatoes (usually cheaper brands). This element made the vodka oily. To disperse the oil, Bond ordered his martinis shaken; thus, in the same scene where he orders the martini, he tells the barman about how vodka made from grain rather than potatoes makes his drink even better.
Melhor, no FAQ do Martini ;
...while we should all defer to the inimitable Mr. Bond on matters such as high-tech spy gadgets, impromptu hand-to-hand combat, and retrograde seduction techniques, his reasoning on this matter is specious. To "bruise" a wine or spirit means to take some action that changes its taste. Agitating and therefore aerating a gin or vodka martini changes its taste: it makes it taste "sharper". It imparts a certain bite or zing. Given this, and given his dislike of a bruised spirit, Bond should insist that his drink be "Stirred, not shaken," since shaking "bruises" the gin more than stirring does.
...Here are the facts: Shaking cools a drink more quickly. Shaking is more likely to chip small shards off the ice, some of which will make their way into the drink, no matter how carefully one strains and pours. Which may be part of the reason why... Although the gin spends less time with the ice when the drink is shaken, shaking a drink actually dilutes it more than stirring does. Very rarely, shaking can produce a chill haze (the precipitation of very small solid particles) from the vermouth, giving the drink a cloudy appearance. Shaking creates tiny bubbles in the mix, which temporarily impart a cloudy appearance to the drink. Shaking causes a certain class of molecules in the liquor (aldehydes) to combine with oxygen more than stirring does. The oxidation of these molecules also slightly alters the flavor, making it "sharper" (Miller, Anistatia R. and Jared M. Brown. Shaken Not Stirred: A Celebration of the Martini. New York: HarperCollins, 1997).