Capture of Fermentation Gas from Fermentation of Grape Must.

During alcoholic fermentation, a considerable amount of carbon dioxide (CO2) is produced, and the stream of CO2 can strip aromatic substances from the fermenting must. Aroma losses during fermentation can be significant and may lead to a reduction in wine quality. This study is focused on new fermentation gas capture technology. In the experiment, gas was captured during the fermentation of sauvignon blanc must. The concentration of individual volatile compounds in the fermentation gas was determined using gas chromatography, and the highest values were achieved by isoamyl acetate, isoamyl alcohol and ethyl decanoate. Ethyl dodecanoate achieved the lowest values of the investigated volatile substances. For sensory assessment, quantitative descriptive analysis (QDA) compared water carbonated with fermentation gas and water carbonated with commercial carbon dioxide for food purposes. Based on the results of this study, it can be concluded that the captured gas containing positive aromatic substances is suitable for the production of carbonated drinks in the food industry.

UV-Induced fingerprint spectroscopy.

Here, we present the potential analytical applications of photochemistry in combination with fluorescence fingerprinting. Our approach analyzes the fluorescence of samples after ultraviolet light (UV) treatment. Especially in presence of metal ions and thiol-containing compounds, the fluorescence behavior changes considerably. The UV-induced reactions (changes) are unique to a given sample composition, resulting in distinct patterns or fingerprints (typically in the 230-600 nm spectral region). This method works without the need for additional chemicals or fluorescent probes, only suitable diluent must be used. The proposed method (UV fingerprinting) suggests the option of recognizing various types of pharmaceuticals, beverages (juices and wines), and other samples within only a few minutes. In some studied samples (e.g. pharmaceuticals), significant changes in fluorescence characteristics (mainly fluorescence intensity) were observed. We believe that the fingerprinting technique can provide an innovative solution for analytical detection.

Effect of Must Hyperoxygenation on Sensory Expression and Chemical Composition of the Resulting Wines.

This paper evaluates the effect of must hyperoxygenation on final wine. Lower concentrations of caftaric acid (0.29 mg·L-1), coutaric acid (1.37 mg·L-1) and Catechin (0.86 mg·L-1) were observed in hyperoxygenated must in contrast to control must (caftaric acid 32.78 mg·L-1, coutaric acid 5.01 mg·L-1 and Catechin 4.45 mg·L-1). In the final wine, hydroxybenzoic acids were found in higher concentrations in the control variant (gallic acid 2.58 mg·L-1, protocatechuic acid 1.02 mg·L-1, vanillic acid 2.05 mg·L-1, syringic acid 2.10 mg·L-1) than in the hyperoxygenated variant (2.01 mg·L-1, 0.86 mg·L-1, 0.98 mg·L-1 and 1.50 mg·L-1 respectively). Higher concentrations of total flavanols (2 mg·L-1 in hyperoxygenated must and 21 mg·L-1 in control must; 7.5 mg·L-1 in hyperoxygenated wine and 19.8 mg·L-1 in control wine) and polyphenols (97 mg·L-1 in hyperoxygenated must and 249 mg·L-1 in control must; 171 mg·L-1 in hyperoxygenated wine and 240 mg·L-1 in control wine) were found in both the must and the control wine. A total of 24 volatiles were determined using gas chromatography mass spectrometry. Statistical differences were achieved for isobutyl alcohol (26.33 mg·L-1 in control wine and 32.84 mg·L-1 in hyperoxygenated wine), or 1-propanol (7.28 mg·L-1 in control wine and 8.51 mg·L-1 in hyperoxygenated wine), while esters such as isoamyl acetate (1534.41 µg·L-1 in control wine and 698.67 µg·L-1 in hyperoxygenated wine), 1-hexyl acetate (136.32 µg·L-1 in control wine and 71.67 µg·L-1 in hyperoxygenated wine) and isobutyl acetate (73.88 µg·L-1 in control wine and 37.27 µg·L-1 in hyperoxygenated wine) had a statistically lower concentration.

Study of carbonyl compounds in white wine production.

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 Grüner 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 SO2 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 SO2 content without any problems.

Use of Anthocyanin Profiles When Differentiating Individual Varietal Wines and Terroirs.

In recent years, the importance of wine authenticity specification has significantly influenced the world wine market. Nowadays, the importance of terroir is emphasised worldwide. Also in European countries, where varietal wines are produced predominantly, the wine authenticity is given an increasing attention. Anthocyanin pigments represent an important group of phenolic substances that are used for the evaluation of wine authenticity. In this study, altogether 17 varietal red wines originating from the village Dolní Kounice (wine-growing region Moravia, Czech Republic) are evaluated. The evaluation involved three varieties, viz. Blaufränkisch (Lemberger), Saint Laurent and Blauer Portugieser as well as three terroirs named Karlov, Sibenicní vrch and Na Nivách. Anthocyanin pigments in varietal red wines were estimated by means of the HPLC method. Thanks to the application of chemometric methods, it was possible to determine the grapevine variety and to classify red wines on the basis of delphinidin-3-O-glucoside (DpGl), malvidin-3-O-glucoside (MvGl) and delphinidin-3-O-acetylglucoside (DpGlAc) content. The terroir was discriminated on the basis of DpGl, MvGl and delphinidin-3-O-p-coumarylglucoside (DpGlCm) content.