Enological behaviour of biofilms formed by genetically-characterized strains of sherry flor yeast

Abstract

The flor yeasts (Saccharomyces cerevisiae) form a biofilm, known as flor velum, on the surface of fino-type sherry wine at the end of the alcoholic fermentation. These film-forming yeasts are responsible for the oxidative transformation of alcohol to acetaldehyde, together with other reactions, which produce the characteristic flavours and aromas of these wines. In this study, we examine the enological behaviour of eight flor yeast strains biofilms in biological aging experiments carried out in the laboratory. Strains with identical chromosomal and mitochondrial DNA patterns and the same origin showed a more closely-related enological behaviour. But the kinetics of growth and acetaldehyde accumulation in the wine were found to be strain-dependent. Moreover, some strains were marked by high acetaldehyde accumulation in their pure cultures during the various phases of the biofilm development. These results provide valuable knowledge for planning technical strategies to improve the biological aging process in the sherry wine industry.