EVIDENCE OF THE PRESENCE OF A 4-MERCAPTO- 4-METHYLPENTAN-2-ONE PRECURSOR IN VITIS-VINIFERA SAUVIGNON BLANC GRAPE VARIETY

A sulfur-containing compound with a powerful boxtree-type odor, 4-merc apto-4-methylpentant-2-one, has been identified in ''Sauvignon blanc'' wines. This compound occurs in the Sauvignon grape juice in the form of an odorless precursor fraction which can be isolated by an especial ly developed technique. When incubated in a synthetic medium, the prec ursor fraction gives off free 4-mercapto-4-methylpentan-2-one during a lcoholic fermentation, The free ketone is also released under in vitro conditions when the precursor is incubated with ascorbic acid,