engleski

Concentrations of L-tryptophan, indole-3-acetic acid and 2-aminoacetophenone in Malvasia

The phenomenon of untypical aging off-flavor, associated with higher concentrations of 2-aminoacetophenone (2-AAP) in white wines, can stem from some technological treatments applied in grape and wine production. In order to find out if a wine is liable to untypical aging off-flavor, it is necessary to determine the concentrations of indole-3-acetic acid and L-tryptophan, which are the precursors of 2-aminoacetophenone. The purpose of this investigation was to determine the influence of soil type and different yeast strains on the levels of L-tryptophan, indole-3-acetic acid and 2-aminoacetophenone in the Malvasia from Istria must and wine. In the 2007 and 2009. grapes were harvested from two different soil type locations (terra Rosa, terra Bianca), in Istria wine growing region, Croatia, and separately vinified. Vinification was carried up with 4 different wine strains ((Fermol Cryoarome, Fermol Assosiee, Uvaferm CS2, Anchor VIN 13). Young wine samples were taken for analysis after completed alcoholic fermentation. Analyses of L-tryptophan and indole-3-acetic acid were performed using Agilent 1100 equipped with autosampler and fluorescence detector. Separation was achieved on Luna C18 (endcapped) column (5 μm packing, 250 x 4.6 mm i.d.), (Phenomenex, USA), protected with guard column from same material (Phenomenex, USA). 2-aminoacetophenone (2-AAP) analyses were performed using gas chromatography-mass spectrometry (GC-MS). 2-AAP was extracted from wine by direct immersion solid phase microextraction (DISPME). Divinylbenzene / carboxen / polydimethylsiloxane SPME fibres were used. Chemical analyses of compared musts and wines in both investigated years showed differences in L-tryptophan, ranging from 260, 2 up to 1065, 6 μg/L, and indole-3-acetic acid concentrations, ranging from 26, 1 up to 71, 3 μg/L, that depend more upon the soil type than yeast strain used. Different soil type and yeast strains also influenced 2-aminoacetophenone concentrations in Malvasia wines, ranging between 0, 3-1, 2 μg/L. Keywords: indole

indole-3-acetic acid ; L-tryptophan ; 2-aminoacetopheno ; wine ; soil type ; yeast

nije evidentirano