engleski

Influence of different yeast strain on metabolism of tryptophan and indole-3-acetic acid as the precursors of „untypical aging off- flavour“ (UTA) in wine

Tryptophan (Trp) and its metabolite indole-3- acetic acid (IAA), are considered to be potential precursors of 2-aminoacetophenone (2- AAP), an aroma compound which is responsible for „untypical ageing off-flavour“ (UTA) in wines. The aim of this research was to establish the difference among yeast strains in metabolism of Trp and IAA during fermentation in Rhein riesling (Vitis vinifera L.) must. Inoculation of must was conducted with four commercial yeast strains (Uvaferm CEG, Lalvin Cross Evolution, Anchor VIN 13 and Anchor exotic SPH). Trp and IAA were determined in four different stages of vinification by high- performance liquid chromatography with fluorescence detection. Results showed that initial Trp concentration was 2, 41 mg/L. Trp was almost completely consumed by all yeast strains till half of fermentation. At the end of fermentation Trp content increased again but difference was shown between yeast strains. Uvaferm CEG strain had highest concentration of Trp in range of 0, 54 mg/L, while Anchor exotic SPH strain had lower concentration of 0, 38 mg/L. Concentrations of total and bound IAA decreased during all fermentations. Initial concentrations of 84, 82 μg/L was found in must whereas free IAA was not detected. At the end of fermentation highest concentration of free IAA was found at Anchor VIN 13 strain (35, 83 μg/L) and lowest at Uvaferm CEG (13, 08 μg/L). It can be concluded that inoculation with different yeast strains has influence on metabolism of Trp and IAA, and that Anchor VIN 13 strain produced highest concentration of free IAA which is main precursor of 2-AAP in wine.

Tryptophan ; indole-3-acetic acid ; 2-aminoacetophenone ; UTA ; yeast strain

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