A major portion of primary wine aroma substances are terpenes. In grape berries, they are primarily located in the skin as sugar-bound monoterpene precursors (glycosides). In this glycosidically bound form, they are neutral in smell: only the respective aglycone is odor-bearing. By enzymatic cleavage of the sugars (monosaccharides or disaccharides), the corresponding monoterpene alcohol (such as linalool or geraniol) is liberated and becomes organoleptically perceptible. Monoterpene alcohol and sugar residues are linked by a glycosidic bond; thus, enzymatic breakdown is carried out by β-glycosidases. These enzymes are differentiated according to their specific activities, which depend on the type of sugar residue to which the terpenes are linked (e.g., arabinose, rhamnose, or apiose). In the course of this project, enzymes with new β-glycosidase activities were evaluated. These enzymes were not inhibited by high glucose concentration and promote a significant increase in aroma release.

Funding Support: Erbsloeh Geisenheim AG, Erbsloehstrasse 1, Geisenheim D-65366, Germany; Institute of Viticulture and Enology Freiburg (WBI), Merzhauserstrasse 119, 79100 Freiburg, Germany