dilution is the process of reducing the concentration or strength of a solution. In the context of cocktails and spirits, dilution most commonly refers to a lowering of alcoholic strength through the addition of water or other ingredients of lower proof.
Dilution has many effects on the organoleptic properties of a beverage and is an important tool of the bartender in preparing an alcoholic drink. Among the most significant effects are changes in viscosity, chemically sensed qualities such as alcoholic “burn,” and the volatility of various aromatic molecules, all of which have a significant influence on perceived flavor. For this reason bartenders attempt to control for the effects of dilution in both design and execution of cocktails in order to produce a desired result.
The most common source of dilution in chilled drinks is ice, which achieves almost all of its cooling effect through melting. This is due to a concept of physics known as the heat of fusion, which is that it takes far more thermal energy to induce a phase change from solid to liquid than it does to raise the temperature of a substance to a similar extent without a phase change. Thus, melting ice chills a drink far more effectively than any material that does not melt. When ice is maintained at or near the temperature of freezing, another significant source of dilution is the liquid water already present on the surface of the ice.
In some instances, dilution may even cause certain dissolved substances to come out of solution. A familiar example of this phenomenon is the so-called louche effect produced when water is added to solutions such as absinthe containing a high concentration of dissolved hydrophobic oils, causing the oils to come out of solution and form a milky microemulsion.
See also louche.
Arnold, Dave. Liquid Intelligence: The Art and Science of the Perfect Cocktail. New York: W. W. Norton, 2014.
Liu, Kevin K. Craft Cocktails at Home: Offbeat Techniques, Contemporary Crowd-Pleasers, and Classics Hacked with Science. N.p.: Kevin Liu, 2013.
Moore, John T. “Mixing Matter Up: Solutions.” In Chemistry for Dummies. Hoboken, NJ: Wiley, 2016.
By: Samuel Lloyd Kinsey