Aromatic compounds released from natural precursors by selected Oenococcus oeni strains during malolactic fermentation

The changes produced at the volatile fraction of a Tempranillo wine added with a natural glycosidic extract and commercial esters by the action of inoculated Oenococcus oeni strains during malolactic fermentation were assessed. The glycosidic extract was obtained from must of Muscat grape variety, and strains used had been selected in a previous work by their glycosidase and esterase activities against synthetic substrates. Fermentation assays were maintained in incubation for 22 days; after that, wines were analysed for their chemical parameters and the volatile compounds. Significant differences in the concentration of some volatile compounds in wines obtained with the different strains were observed, which could affect the sensory characteristics of the wines. The assayed strains were able to release terpenes, norisoprenoids and C6 alcohols, and to hydrolyse esters such as butyl acetate and 2-phenylethyl acetate. These results revealed that strains presented both glycosidase and esterase activities although in a strain-dependent manner. Strains Da32 and Ab11 are good candidates to be used when floral wines are desired, while strain 93 is the best preserving the fruity aroma of wines.