Enzyme Contribution of Non-Saccharomyces Yeasts to Wine Production

The fermentation of grape must to produce wine is a biologically complex process, carried on by yeasts and malolactic bacteria. The yeasts present in spontaneous fermentation may be divided into two groups, the Saccharomyces yeasts, particularly S. cerevisiae, and the non-Saccharomyces yeasts which include members of the genera Rhodotorula, Pichia, Candida, Debaryomyces, Metschtnikowia, Hansenula and Hanseniaspora. S. cerevisiae yeasts are able to convert sugar into ethanol and CO2 via fermentation. They have been used for thousands of years by mankind for the production of fermented beverages and foods, including wine. Their enzymes provide interesting wine organoleptic characteristics. β-Glucosidase activity is involved in the release of terpenes to wine, thus contributing to varietal aroma. β-Xylosidase enzyme is also interesting in industry due to its involvement in the degradation of hemicellulose by hydrolyzing its main heteroglycan (xylan). The ability of yeasts to release proteases has been observed by many researchers because of their potential to degrade haze proteins in wine and to generate nutrient sources for microorganisms. Moreover, these enzymes are interesting in biotechnology, for use in food processing such as cheese, pickles or sausage.