The varietal flavour of grapes is mainly determined
by the accumulation and pro®le of volatile secondary
metabolites in V. vinifera [61]. However, a high
percentage of these metabolites occur as their
respective, non-volatile O-glycosides. Several studies
have shown that increased enzymatic hydrolysis
of aroma precursors present in grape juice can
liberate the aglycone to intensify the varietal
character of wines [15]. For instance, terpenols
such as geraniol and nerol can be released from
terpenyl-glycosides by the grape-derived b-D-glycosidase
activity present in muscat grape juice.
However, grape glycosidases are unable to hydrolyze
sugar conjugates of tertiary alcohols such as
linalool [15].