The study evaluated the effect of different fining treatments such as oenological additives and the influence of oxygen and hyperoxygenation on the phenolic and aroma composition of grape musts and wines. The oxidative method, hyperoxygenation and fining agents polyvinyl polypyrrolidone (PVPP), pea protein and chitosan were used for the removal of phenolic compounds compared to the control experiment. The content of phenolic substances was determined by high performance liquid chromatography. A total of 24 volatiles—higher alcohols, ethyl esters and acetate esters were determined using gas chromatography-mass spectrometry. A lower concentration of caftaric acid was observed in hyperoxygenated (0.21 mg·L⁻¹), oxidated (0.37 mg·L⁻¹), PVPP-treated (35.50 mg·L⁻¹), pea protein-treated (42.56 mg·L⁻¹) and chitosan-treated variants (44.40 mg·L⁻¹), in contrast to the control must (caftaric acid 50.38 mg·L⁻¹). In the final wine, the results were similar with a lower concentration of caftaric acid in hyperoxygenated (7.10 mg·L⁻¹), oxidated (14.88 mg·L⁻¹), PVPP-treated (23.49 mg·L⁻¹), pea protein-treated (29.49 mg·L⁻¹) and chitosan-treated variant (30.02 mg·L⁻¹), in contrast to the control wine (caftaric acid 32.19 mg·L⁻¹).

This article focuses on the effect of yeast strains, vintage, and must sugar content on the amino-acid content of sparkling wines produced by the traditional method. In the experiment, the amino-acid concentrations before and after secondary fermentation, depending on the type of yeast used (basic wine without secondary fermentation, wine fermented with immobilized yeast, and wine fermented with classical Champagne yeast) and the sugar content of the must (170, 190, and 210 g per liter), and the vintage (2010 and 2011), were evaluated. Concentrations of 20 free amino acids in 18 wine variants were analyzed by ion-exchange liquid chromatography with postcolony ninhydrin derivatization and photometric detection. Results of the study show an increase in all the amino acids represented, except ornithine, after secondary fermentation. The average content of each amino acid in the basic wine, wine fermented with immobilized yeast, and wine fermented with classical Champagne yeast was higher in the variant where classical yeast was used. In this variant, the concentrations of alanine, glutamic acid, lysine, arginine, phenylalanine, valine, and glycine were almost twice as high as in the other variants. A higher proportion of most amino acids was observed in the year 2011; only for amino acids lysine, leucine, phenylalanine, tyrosine, ornithine, histidine, and methionine was a higher concentration observed in the year 2010. A higher concentration of released amino acids was also observed in wine produced from must with a higher sugar content (21° NM).

Carbonyl compounds, especially acetaldehyde in white wines which have a detrimental effect on the aroma and overall stability of wine, were studied.. Seven wine samples of Gruner Veltliner were produced of one input raw material of grapes, all with different dosage of SO2. The sulfur dioxide was maintained at a fixed level during the maturation process and sampled at six months. The grapes were processed, fermented, aged for three months in stainless steel tanks, prepared for bottling, bottled, and then aged in the bottle. In the samples taken, the volume of acetaldehyde, pyruvate, 2-oxoglutarate, diacetyl, and acetoin was determined by HPLC with diode array detection. Individual forms of SO(2)were determined by iodometric titration. The wine that was matured on the lees and without the addition of SO2(variant (0/0/0)) contained the lowest amount of all compounds measured. For example, the volume of acetaldehyde for this wine was 2.7 mg/L at the end of the experiment. The results of the sensory analysis showed that such wine could compete with wines with higher SO(2)content without any problems.

The presented article is focused on the study of amino acid metabolism and the related production of fusel alcohols and their esters in the secondary fermentation of sparkling wines. The production of fusel alcohols and their esters as a by-product of the metabolism of individual amino acids during secondary fermentation and the influence of secondary fermentation with the use of individual amino acids as the only source of nitrogen was analyzed. Ten different amino acids were used. We used a control variant with the addition of ammonium hydrogen phosphate as an inorganic source of nitrogen and a control variant with an organic source of nitrogen in the form of an inactivated yeast, Saccharomyces cerevisiae, which contained all 20 amino acids in their natural ratio. The higher alcohols investigated were isoamyl alcohol, isobutanol, 2-phenylethanol, 1-propanol, 1-hexanol, and 1-butanol. The following esters of the higher alcohols were subsequently used: isoamyl acetate, hexyl acetate, phenethyl acetate, and isobutyl acetate. The individual fusel alcohols and esters were analyzed using GC-MS gas chromatography. The results pointed to different amino acid metabolisms in relation to the amount and production of fusel alcohols within the secondary fermentation and thus the sensory profile of sparkling wine.