Terpene compounds as possible precursors of 1,8-cineole in red grapes and wines.

While the contribution of 1,8-cineole to the aroma of wine has been reported, it is a matter of controversy that the vineyards producing such wines are surrounded by Eucalyptus trees, which may contribute their essence to the grapes. However, experimental information presented in this paper suggests that 1,8-cineole can be produced by chemical transformation of limonene and alpha-terpineol, and this process may be responsible for the occurrence of Eucalyptus-like aroma in Tannat wines from vines not grown in the vicinity of Eucalyptus trees. A mechanism for the chemical transformation of these aroma compounds is proposed.