Terpenes | In his book, Italy’s Native Wine Grape Terroirs, Dr Ian D’Agata defines terpenes as hydrocarbon molecules made up of carbon and hydrogen atoms. The concentration and type of terpenes found in grapes influences how aromatic or not the wine will be, he says. Terpenes in grapes are found in two forms, the free or aromatic form and the bound (non-aromatic) form. Bound terpenes can be freed from their bond, D’Agata says, leaving them the role of what he calls aromatic-molecule reservoirs. See aromatic grape varieties for how D’Agata classifies some key wine grapes from not aromatic at all to strongly aromatic.
Dr Ian d’Agata, Italy’s Native Wine Grape Terroirs (University of California Press, 2019).