Prospection of indigenous yeasts from Uruguayan Tannat vineyards for oenological applications.

Prospection of yeasts from oenological environments can provide knowledge of new native strains that are capable of fermenting must and positively influence the composition and sensory characteristics of the wine. This work addressed the biotechnological characterization of indigenous yeasts of Tannat must, an emblematic and widespread vineyard of Uruguay. Fifty-three yeast isolates were morphologically characterized and further identified by amplification and sequencing of ITS and D1-D2 regions, grouping into a total of fifteen species.

Influence of beta glucosidases from native yeast on the aroma of Muscat and Tannat wines.

It is now well established that β-glucosidases (BGLs) from non-Saccharomyces yeasts are key enzymes that hydrolyze grape-derived aroma precursors enhancing the flavour of wines. This work reports on the specificity for wine glycosides and the impact on wine aroma, of three native yeast β-glucosidases. Volatile compounds were analyzed by gas-chromatography and mass spectroscopy (GC-MS) and wine aroma was studied by sensory analysis.

Aroma enhancement in wines using co-immobilized Aspergillus niger glycosidases.

A major fraction of monoterpenes and norisoprenoids in young wines is conjugated to sugars representing a significant reservoir of aromatic precursors. To promote their release, β-glucosidase, α-arabinosidase, and α-rhamnosidase from a commercial Aspergillus niger preparation, were immobilized onto acrylic beads. The aim of this work was the development and application of an immobilized biocatalyst, due to the well-known advantages over soluble enzyme preparations: control of the reaction progress and preparation of enzyme-free products.

Immobilization of enzymes: a literature survey.

The term immobilized enzymes refers to "enzymes physically confined or localized in a certain defined region of space with retention of their catalytic activities, and which can be used repeatedly and continuously." Immobilized enzymes are currently the subject of considerable interest because of their advantages over soluble enzymes. In addition to their use in industrial processes, the immobilization techniques are the basis for making a number of biotechnology products with application in diagnostics, bioaffinity chromatography, and biosensors.

One-step purification and characterization of an intracellular beta-glucosidase from Metschnikowia pulcherrima.

A collection of 60 non-Saccharomyces yeasts isolated from grape musts in Uruguayan vineyards was screened for beta-glucosidase activity and Metschnikowia pulcherrima was the best source of this enzyme activity. Its major beta-glucosidase was successfully purified to homogeneity by ion-exchange chromatography on amino-agarose gel. The enzyme exhibited an optimum catalytic activity at 50 degrees C and pH 4.