Biological aging of sherry wines using pure cultures of two flor yeast strains under controlled microaeration

Sherry wines obtained after biological aging for an average of 0, 2, and 4 years were inoculated separately with the flor yeast strains Saccharomyces cerevisiae var. capensis and Saccharomyces bayanus and subjected to short, periodic microaeration to a dissolved oxygen concentration of 4 mg L(-1) after formation of the yeast film. A principal component analysis with the acetaldehyde, ethanol, volatile acidity, and glycerol concentrations obtained was performed. The first principal component was found to account for 49.5% of the overall variance and to be defined mainly by glycerol and ethanol. The second component accounted for 38.8% of the variance and was defined by volatile acidity and acetaldehyde. The conditions used in the tests allowed the biological aging of the wines to be substantially shortened. Thus, 42 days after flor-film formation by S. cerevisiae var. capensis, 0- and 2-year-old wines exhibited parameter values similar to those obtained for the wine aged for 4 years. The wines inoculated with S. bayanus exhibited high acetaldehyde concentrations and ethanol levels above 15% (v/v)-sherry wines with alcohol concentrations below 14.5% are undesirable-, so one need not exclude the sequential or simultaneous inoculation of S. bayanus together with S. cerevisiae var. capensis in order to improve the biological aging process.