terpenes comprise a large group of hydrocarbons that give many different flowers, trees, fruits, roots, and other plant materials their pungent aromas, many of which find their ways into distilled spirits. The word terpene is derived from turpentine, as the resinous aromas of conifers are largely due to terpenes. But so are the complex, intense aromas of hops and cannabis—as well as those of mint and juniper berries and even roses and lemon peel. See hops.
Some terpenes can bring very pleasant aromas to beverages (they are largely responsible for the fruity aromas found in brandies); others, such as the terpenes that drive the aroma of Penicillium roquefortii—a fungus used to create blue cheeses such as Roquefort, Stilton, and gorgonzola—are rather less welcome. In 1983, Nykänen and Suomalainen compiled a list of at least 92 “terpene … compounds and their oxygenated derivatives” found in a limited sampling of chiefly European spirits. An analysis of gin, for instance, turned up—among many others—myrcene, limonene, α- and β-pinene, thujene, geraniol, and bornanone (which gives camphor its flavor). Bornanone and geraniol are also found in cognac, as well as γ-terpineol, damascenone, and a large number of other terpenes. Menthol turns up in Jamaican rum, β-ionone in whisky, and so forth.
Terpenes (or terpenoids, which are terpenes rearranged by oxidation or other chemical actions) are often constituent elements in essential oils and are added to compounded spirits in that form. These are often more faithful representatives of their plant sources than distilled spirits, since terpenes tend to break down with increased temperature and acidity, and the hot, acid environment of the still degrades all but the most volatile ones. This produces a simplified aroma, dominated by the terpenes from the raw material that have the lowest aroma threshold (i.e., the ones that we smell first), without the heavier ones to give them depth. Thus, for example, a crème de menthe made exclusively by distillation will taste like menthol, not fresh mint.
See also acetaldehyde and phenols.
Jackson, Ronald. Wine Science: Principles and Applications, 4th ed. San Diego: Academic Press, 2014.
Marais, J. “Terpenes in the Aroma of Grapes and Wines: A Review.” South African Journal of Enology and Viticulture 4, no. 2 (1983): 49–58.
Nykänen, Lalli, and Heikki Suomalainen. Aroma of Beer, Wine, and Distilled Alcoholic Beverages. Berlin: Akademie Verlag, 1983.
By: Doug Frost