Oenological characterization of indigenous yeast species involved in fermentation of Tokaji aszú

Tokaji Aszú is traditionally fermented by the indigenous yeast biota, which is different from that of normal wines. Numerous native strains of the most important species, S. cerevisiae and S. bayanus (partially reclassified as S. uvarum), as well as Candida stellata and C. zemplinina were tested for technological traits under the same conditions. The most important conclusions of this work are as follows. • Local Saccharomyces cerevisiae and S. bayanus strains isolated from the indigenous yeast biota of Tokaji Aszú have considerable diversity in oenological properties. • S. cerevisiae strains grow and ferment aszú wines better than S. bayanus strains. The two species have different impact on the chemical composition of wine, both of them having positive and negative features in comparison. A combined use of the two species should be investigated. • The typical non-Saccharomyces species of Tokaji Aszú, as single cultures, generally could not ferment the aszú wine properly. • The most important non-Saccharomyces species, C. stellata and C. zemplinina are very similar from oenological aspects. They are highly fructophylic producing high glucose and fructose ratio (1.4-2.7) in the aszú wine after fermentation. These highly fructophylic species may alter the normally low (close to 0.5) glucose and fructose ratio in the aszú wine, if Saccharomyces strains fail to grow up during spontaneous fermentation, which may cause problems in the official origin control of Tokaji Aszú