engleski

Biological wine deacidification with different yeast strains

Wine quality is determined by large number of factors with acidity being one of the most important. To establish the best possible harmony of wine, all its components must be well balanced which is very hard to acomplish in wines with high acid content. There are a few ways of reducing the wine acidity. The most preffered is biological acidification which can be acomplished by use of lactic acid bacteria performing malolactic fermentation (MLF) and by use of secial yeast strains which degrade malic acid to ethanol thus performing maloethanolic fermentation (MEF). A large number of factors, including SO2 content, pH, temperature and ethanol content have their influence on MLF, but, in some cases they od not support MLF in wine. Besides deacidification, MLF changes some aromac characteristics of wine, and those changes sometimes might be prefferable and sometimes not. The method of deacidification by use of yeast is not as well investigated as MLF. That was the main reason why this research was initiated concerning deacidification and its inflence on wine quality. Must of the Chardonnay cultivar was inoculated with indigenous Saccharomyces cerevisiae strain S1 isolated from the Zagreb wine region. S1 strain showed high capacity of malic acid decomposition during the preliminary investigations. Another inoculant was Schizosaccharomyces pombe, well known for complete malic acid degradation and the last inoculant was Lalvin 71B strain (Lallemand) which also has a biological deacidification ability. Spontaneous fermentation with indigenous microorganisms served as control. Malic acid content as well as the mechanism of degradation were determined by chemical and sensory analysis. Results confirmed different efficiencies of the above mentioned strains with regard to the degradation of malic acid. Saccharomyces cerevisiae strain S1 and Schizosaccharomyces pombe strain F confirmed its degrading ability, strain 71 B degraded a smaller amount, while indigenous microorganisms had a no effect on degradation of malic acid. Organoleptic evaluation determined a high divergency in quality of the produced wines.

yeast; maloethanolic fermentation; malic acid; acidity

nije evidentirano