Isolation of intact glycosidic aroma precursors from grape juice by hydrophilic interaction liquid chromatography

Background and Aims: Aroma precursors in grape juice include glycosylated terpenoids or benzenoids. The separation of these polar substances has been achieved by several chromatographic techniques but often after the esterification of the sugar hydroxyls. We aimed to develop a high-performance liquid chromatography method to isolate the glycoconjugates in their natural form. Methods and Results: The glycoside fraction was extracted from fresh grape juice, treated with lead (II) acetate to precipitate phenolic compounds and finally separated by hydrophilic interaction liquid chromatography. Three compounds were isolated, and their structures elucidated by means of spectroscopic data; one revealed previously unreported structural features. Conclusions: Our hydrophilic interaction liquid chromatography method has been proven effective for the purification of the complex blend of many chemical compounds that contribute to grape and wine flavour. Significance of the Study: The present article proposes a new, straightforward procedure for the isolation of flavour glycoconjugates.