freeze distillation , or ice distillation, is a term for the ancient practice of fractional freezing, which is also known as freeze concentration. At the heart of distillation is the separation of components by evaporation and condensation. The process works because of the different boiling points of alcohol and water. But their melting points—the points at which they go from solid to liquid—differ as well (for various reasons it is easier to reliably measure a substance’s melting point than its freezing point, at which it goes from liquid to solid). The melting point of ethanol is −114° C, and the melting point of water is 0° C. Ice distillation uses that fact to isolate the alcohol through successive freezing and thawing. Once the temperature of a fermented beverage is lowered beyond the melting point of water, the water begins to freeze, and the remaining liquid has a higher concentration of ethanol. This allows the distiller to strain out the water from the ethanol-rich mixture. This process, commonly referred to as “jacking,” has been used for centuries. It is often credited as the origin of both vodka and, in colonial America, the apple brandy spirit applejack. However, concentration by freezing is less efficient than distillation and leaves many undesirable compounds, like methanol and fusel oils, in the resulting liquid. Therefore, it is no longer widely used in the production of alcoholic beverages. However, some products like Eisbock beers are still made using the fractional freezing method.
applejack; distillation, process; and vodka.Pokhlebkin, William. A History of Vodka. Translated Renfrey Clarke. London: Verso, 1991.
Rowley, Matthew B. The Joy of Moonshine. New York: Lark, 2007.
By: Jason Grizzanti