In addition to ampelographic interventions and climatic conditions in the vineyard, the quality of the wine depends on the yeast starter cultures used, which provide guided alcoholic fermentation. In the framework of the improvement of fermentative, technological, aromatic and metabolic properties of selected yeast strains, UV-mutagenesis was used. We determined that prolonged yeast exposure to UV-radiation has a negative effect on the cell viability, and that the effect of UV-radiation is reflected in changed macromorphological properties of yeast colonies such as in irregular shapes with a jagged edge and in brighter and more transparent color. Compared to the non treated yeasts the fermentation kinetics of the yeast mutant generally do not differ from the control strains, but the differences in the analysis of the physicochemical properties of the produced wines are evident, especially in the production of volatile acids, glycerol concentration and in the content of reducing sugars. The results of wine quality parameters show a statistically significant influence of exposure of yeasts to UV-radiation and the yeast strains used. The scalar increase of grape must volume and the more osmotic fermentation conditions contributed to the development of negative wine aromas, especially in the third fermentation experiment where we used 30 seconds irradiated mutant of the strain LALVIN EC1118 in the grape must of the Malvasia variety.
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