EVOLUTION OF PHYTOSTEROLS IN CHARDONNAY GRAPE BERRY SKINS DURING LASTSTAGES OF RIPENING

This study presents the results of rapid phytosterols analysis in grap e skins during last stages of ripening. The analysis is related to the evolution of sterol content by comparison with ripening degree on two vineyards of Chardonnay grape variety in Burgundy: Meursault ler Cru and Hautes Cotes de Beaune. The characterization of sterols is realize d by using combined gas chromatography-mass spectrometry from trimethy lsilyl ethers of sterols. After optimization of extraction by azeotrop ic mixture (chloroform/methanol 2:1 v/v), the analysis allows to ident ify four sterols in grape skins: beta-sitosterol, campesterol, stigmas terol and lanosterol. In all the samples, beta-sitosterol is the major phytosterol (86 to 89 % of the total detected phytosterols). The evol ution of phytosterols content during last stages of ripening shows a s imilar comportment of beta-sitosterol, campesterol and stigmasterol in grape skins: the maturation induces a loss of phytosterols in grape s kins. An increase of phytosterol contents occurs at peak maturity and can be related with over-maturation phenomenon. The relationship betwe en phytosterol content in grape skins and S/A ratio indicates a marked ly negative correlation.