Formation of Furfurylthiol Exhibiting a Strong Coffee Aroma during Oak Barrel Fermentation from Furfural Released by Toasted Staves

Abstract

Furfurylthiol (FFT) is formed in white wines during alcoholic fermentation in the barrel from the furfural released by toasted staves. The quantity of furfural released into the must has a decisive effect on the quantity of FFT in the finished wine. Wines fermented in new barrels thus contain larger quantities of FFT than those fermented in used barrels. Fermentation conditions favorable to an excess production of H₂S (hydrogen sulfide) by the yeast promote the formation of this volatile thiol. The presence of this volatile thiol in white wines is, therefore, closely related to the yeast's sulfur metabolism. Keywords: Furfurylthiol; furfural; hydrogen sulfide; coffee aroma; barrel fermentation; white wines; assimilable nitrogen