Stir bar sorptive extraction applied to volatile constituents evolution during Vitis vinifera ripening.

The stir bar sorptive extraction (SBSE) technique is used to determine volatile constituents in Monastrell grapes. The method proposed involves a maceration step lasting 2 h and a sorption time of 6 h. The coefficients of variation obtained were <4% in the case of the volatile compounds and <2% for the internal standard. The behavior of the volatiles during grape ripening was studied, and 34 compounds were determined, among which geranyl acetone, geranyl butyrate, farnesol, and a bicycloterpene, tentatively identified as 6-methylene[3.1.0]byciclohexane, were recorded for the first time in this variety. The highest terpene and norisoprenoid contents together with the lowest values of C6 compounds were observed during the fifth week of ripening, meaning that this would be the optimal time for harvesting in terms of volatile compounds. Copyright 2004 American Chemical Society