Accumulation of vanillin during barrel-aging of white, red, and model wines.

Abstract

A method for the rapid and accurate analysis of vanillin in wine, using stable isotope dilution analysis and gas chromatography/mass spectrometry, has been developed and applied to 64 oak barrel-aged white, red, and model wines. Following barrel fermentation and maturation on yeast lees, the concentration of vanillin in the white wines was only about one-third of that in the model wines stored for the same period. Once the yeast lees were removed, however, the white and model wines accumulated vanillin at a similar rate, which indicated that biological reduction of vanillin occurred only prior to racking. After 93 weeks in barrels, the concentration of vanillin in the red wines was less than one-half that in the model wines, and vanillin was further depleted during subsequent bottle storage of the red wines for 2 years at cellar temperature. For the model and red wines, the mean concentration of vanillin in barrels made from French oak, seasoned and coopered in Australia, was significantly higher than that for wines stored in barrels made from the same wood, but seasoned and coopered in France. In the white wines, extensive biological transformation of vanillin associated with yeast activity during the initial weeks of maturation appears to have nullified this seasoning/ coopering effect. Oak origin had no significant influence on the final vanillin concentration in the wines.