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.

Design and validation of an STR hexaplex assay for DNA profiling of grapevine cultivars.

Although the analysis of length polymorphism at STR loci has become a method of choice for grape cultivar identification, the standardization of methods for this purpose lags behind that of methods for DNA profiling in human and animal forensic genetics. The aim of this study was thus to design and validate a grapevine STR protocol with a practically useful level of multiplexing. Using free bioinformatics tools, published primer sequences, and nucleotide databases, we constructed and optimized a primer set for the simultaneous analysis of six STR loci (VVIi51, scu08vv, scu05vv, VVMD17, VrZAG47, and VrZAG83) by multiplex PCR and CE with laser-induced fluorescence, and tested it on 90 grape cultivars. The new protocol requires subnanogram quantities of the DNA template and enables automated, high-throughput genetic analysis with reasonable discriminatory power. As such, it represents a step toward further standardization of grape DNA profiling.

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.

Evaluation of drought tolerance of new grapevine rootstock hybrids.

The drought tolerance is a very important property of grapevine rootstocks. For that reason the breeding and selection of new rootstock varieties is focused also on the evaluation of their drought tolerance. In this experiment, altogether 20 new hybrids and 4 existing rootstock varieties were compared and evaluated. The experimental scheme involved 3 variants of water supply. Evaluated were the following properties: growth intensity of annual shoots, CCI (chlorophyll content index) and visual characteristics of plants. The most resistant were hybrids from the pedigree groups C (Binova x Börner), D /Binova x/(Binova x Teleki 5C/) x Börner/, and F (Teleki5 Cx Börner). The following hybrids were classified as drought-tolerant: 17-1-6 (C); 17-1-9 (C); 17-6-2 (C); 17-6-9 (C); 17-8-2 (D) and 9-20-1 (F). Based on obtained experimental results and also on correlations existing between individual traits it can be concluded that practically all traits under study may be used when evaluating the resistance of plants to drought. The obtained results indicated that the Börner rootstock (and thus also the species Vitis cinerea) can be used as a suitable genetic resource for the purpose of the breeding grapevine rootstocks for tolerance to drought.

Utilization of capillary electrophoresis/mass spectrometry (CE/MSn) for the study of anthocyanin dyes.

Hyphenation of capillary electrophoresis with electrospray ionization mass spectrometry was utilized for the monitoring of anthocyanins in wine and wine musts. CE/MS was performed in two electrolytes: 1) an acidic one (chloroacetate-ammonium, pH 2) and 2) a basic one with high selectivity towards derivatives containing vicinal hydroxy groups (borate-ammonium, pH 9). The setup of MS was optimized and the fragmentation of common anthocyanins was studied in detail. Attention was also focused on the fragmentation of anthocyanidin skeleton. The anthocyanidins substituted with hydroxy groups fragment via a cascade of neutral losses of water and carbon monoxide. Fragmentation of anthocyanidins containing a methoxy group on their B-ring starts with the cleavage of methane and/or methyl radical. The optimized method was utilized for the monitoring of changes in anthocyanin profile in red wines as well as the process of release of anthocyanins to wine must.