Identification of key precursors of eugenol and Syringol in wines using a Pseudo-targeted Metabolomic approach

Elevated levels of eugenol and syringol in wines have been observed to impart a smoky, medicinal, and spicy aroma, particularly in wines produced from East Asian species. The precursors of these compounds remain to be elucidated. Therefore, a novel pseudo-targeted metabolomic approach was proposed to screen the key precursors of eugenol and syringol in grape berries. Subsequently, the identified precursors were validated through hydrolysis experiments. The results demonstrated that the key precursors of eugenol were four glycosidic forms present in the berry, including eugenol-β-D-rutinoside, eugenol-dihexose, eugenol-hexose-pentose, and eugenol-hexose glucoside. Similarly, the key precursors of syringol were five glycosidic forms of syringol present in the berry, which included two syringol-dihexoses, two syringol-hexose-deoxyhexoses, and one syringol-hexose-pentose. The pseudo-targeted metabolomic approach proved an effective methodology in this study, offering alternative insights that could inform similar investigations.