I once took part in a vodka tasting contest, in which participants tried to tell an expensive brand from a cheap one. I don't recall the exact outcome, for obvious reasons. But I do know that several people swore they could taste the difference. Well, maybe they could. Because according to a study in the Journal of agricultural and Food Chemistry, different vodkas can have different molecular "structures," which could drive drinkers to favor one brand over another. Vodka's an alcoholic beverage that's supposed to be relatively flavorless. So researchers got to wondering: how come people who enjoy the stuff often express brand preference? Being good little scientists, they trotted out their spectroscopic equipment and examined the chemical signatures of five different vodkas. What they found is that each brand differs in how its ethanol molecules cluster. In the ethanol-water mix we call vodka, some of the ethanol molecules get surrounded by a sort of "cage" made of water. And different brands differ in how much ethanol is caged.