THE EXTRACTION OF VOLATILE COMPOUNDS FROM FRENCH AND AMERICAN OAK BARRELS IN CHARDONNAY DURING 3 SUCCESSIVE VINTAGES

Fifteen barrel lots - 7 American, 6 French and 2 Hungarian - each cont aining 10 barrels, were used for the fermentation and sur lies aging ( 7 months) of Chardonnay wines in three consecutive vintages (1992, 199 3, and 1994). Barrel samples were taken periodically throughout the ag ing process and after filtration and bottling each year. Each wine sam ple was extracted with dichloromethane and concentrated under nitrogen gas before analysis by capillary gas chromatography. Twenty-five comp ounds were identified including, 10 compounds generally recognized in the literature as being oak-related. It was found that the extraction of each oak-related compound from the barrels into the wine followed a curve unique to that compound and that extraction rates were lower in the one-year-old barrels than in the new barrels. These curves reflec ted an exponential approach to a limit, suggesting that extraction is diffusion-controlled Extraction rates were slower in year 2 than in ye ar 1. In comparing data from the two successive vintages, concentratio ns of most oak-related compounds, especially those related to toasting , decreased significantly in the second year. However, levels of beta- methyl-gamma-octalactone, particularly the cis isomer (the more import ant isomer in sensory terms), were significantly higher in the wines a ged in the one-year-old barrels. However, in the two-year-old barrels (year 3 of the experiment), beta-methyl-gamma-octalactone, concentrati ons decreased to levels lower than those found in year 1.