Recently, the possible use of enzymes for flavor enhancement has attracted much attention. Several glycosidases have been studied for their potential to liberate aroma-rich terpenes bonded to glucosides which are found in different fruits juices (mango, passion fruit, cherry, etc), musts and wines. The aromatic precursors also undergo slow chemical hydrolysis during aging of the wine, however, certain fragrant precursors, such as linalool, nerol, and geraniol may be rearranged into less fragrant compounds so that after aging, an aromatic wine can actually have a less intense aroma. Given its high specificity, enzymatic hydrolysis releases the terpenols bound to the glycosidic residues more rapidly and in a selective manner without bringing about structural alterations to the monoterpenes, thus developing a more natural aroma.

We want to isolate and characterize a b-glucosidase (b-D-glucose glucohydrolase) able to efficiently hydrolyse bound aroma from fruit juice or wine. We began with the optimization of growth conditions of a local yeast strain isolated from fermenting must.

With regard to the envisaged exploitation of glucosidases, three important properties of the hydrolases have to be considered: (i) specificity, (ii) pH optimum, and (iii) glucose as well as ethanol tolerance. Such an enzyme has a great potential in the wine and fruit juice industry, since the quantities of bound monoterpenes in most fruit juices and wines are usually relatively high. Moreover, the study includes the development of immobilized biocatalysts for such flavor enrichment to enable enzyme reuse and its removal from the final product. The use of a “tailor made” Monoaminoethyl-N-aminoethyl- (MANAE) adsorbent allowed the immobilization with concomitant purification of the major glucosidase activities of the extract.

With this b-glucosidase biocatalysts, aromatization studies and sensorial methods for the determination of released aroma in wines will be performed.

Paula Gonzalez Pombo