Study of Some Components of the Unsaponifiable Fraction in the Skin of Grapes

Abstract

Fourteen varieties of grapes characteristic of the Piedmont region were analyzed. The dried skins were first Soxhlet extracted with chloroform and the unsaponifiable fraction was separated on TLC. Quantitative gas chromatographic analysis of the major fractions was performed. In the sterolic fraction, the following compounds were identified: β-Sitosterol, campesterol and stigmasterol. Among the triterpenoids, the presence of erytrodiol was observed plus a compound not yet mentioned in viticulture literature. That compound, identified through IR, GC/MS analysis and reactions characteristic of the carbonyl group, presents a structure analogous to oleanoic acid with the aldehydic group in Position 17. From this data, significant differences were observed, both from a qualitative and a quantitative point view, in the varieties possessing distinct aromatic characteristics: Brachetto, Malvasia, and Moscato.