Gruner Veltliner Research Articles

Molecular Fingerprinting and Microbiological Characterisation of Selected Vitis vinifera L. Varieties.

The aim of the study was to analyse selected aspects of the natural variability of selected varieties of Vitis vinifera. Grapevine is one of the most popular and desirable crops in the world due to the great tradition of wine production, but grape extracts also have a wide range of pharmaceutical effects on the human body. It is important to identify different varieties for the conservation of genetic resources, but also for commercial and cultivation purposes. The variability of conserved DNA-derived polymorphism profiles, as well as microbial characteristics, were analysed in this study. Six different varieties of Vitis vinifera L. were used in the study: Cabernet Savignon, Chardonney, Welschriesling, Weisser Riesling, Gewurztramines and Gruner Veltliner. Genetic polymorphism was analysed by CDDP markers for WRKY genes. Polymorphic amplicon profiles were generated by all primer combinations used in the study. Gruner Veltliner and Welschriesling were the most similar, with a similarity value at 0.778. Microbiological quality of grape and antimicrobial activity against Gram-positive and Gram-negative bacteria and yeasts were analysed further. The plate diluting method for microbial quality and the disc diffusion method for antimicrobial activity were evaluated. The number of total count of bacteria ranged between 3.12 in Cabernet Sauvignon to 3.62 log cfu/g in Grűner Veltliner. The best antimicrobial activity showed Gewurztramines against Salmonella enterica, Yersinia enterocolitica, Pseudomonas aeroginosa, Staphylococcus aureus, Listeria monocytogenes, Candida albicans, Candida krusei, and Candida tropicalis. The best antimicrobial activity was found against Enterococcus faecalis in variety Weisser Riesling.

Alcoholic Fermentation Monitoring and pH Prediction in Red and White Wine by Combining Spontaneous Raman Spectroscopy and Machine Learning Algorithms

In the following study, total sugar concentrations before and during alcoholic fermentation, as well as ethanol concentrations and pH levels after fermentation, of red and white wine grapes were successfully predicted using Raman spectroscopy. Fluorescing compounds such as anthocyanins and pigmented phenolics found in red wine present one of the primary limitations of enological analysis using Raman spectroscopy. Unlike the spontaneous Raman effect, fluorescence is a highly efficient process and consequently emits a much stronger signal than spontaneous Raman scattering. For this reason, many enological applications of Raman spectroscopy are impractical as the more subtle Raman spectrum of any red wine sample is in large part masked by fluorescing compounds present in the wine. This work employs a simple extraction method to mitigate fluorescence in finished red wines. Ethanol and total sugars (fructose plus glucose) of wines made from red (Cabernet Sauvignon) and white (Chardonnay, Sauvignon Blanc, and Gruner Veltliner) varieties were modeled using support vector regression (SVR), partial least squares regression (PLSR) and Ridge regression (RR). The results, which compared the predicted to measured total sugar concentrations before and during fermentation, were excellent (R2SVR = 0.96, R2PLSR = 0.95, R2RR = 0.95, RMSESVR = 1.59, RMSEPLSR = 1.57, RMSERR = 1.57), as were the ethanol and pH predictions for finished wines after phenolic stripping with polyvinylpolypyrrolidone (R2SVR = 0.98, R2PLSR = 0.99, R2RR = 0.99, RMSESVR = 0.23, RMSEPLSR = 0.21, RMSERR = 0.23). The results suggest that Raman spectroscopy is a viable tool for rapid and trustworthy fermentation monitoring.

Impacts of Early Leaf Removal and Cluster Thinning on Grüner Veltliner Production, Fruit Composition, and Vine Health

A traditional crop load regulation technique, cluster thinning (CT), was compared to a more innovative technique, early leaf removal (ELR) applied either at trace bloom (TBLR) or fruit set (FSLR), on high-yielding and vigorous Vitis vinifera cv. Gruner Veltliner. Treatment effects on key production parameters, Botrytis bunch rot, tolerance to winter temperatures, and production costs were evaluated and compared to an untreated control over two years. Compared to CT, we hypothesized that ELR would improve fruit composition, reduce Botrytis bunch rot, and decrease grower costs. Yield regulation imposed by CT was significantly higher (39.3%) than that of TBLR (12.6%) or FSLR (13.3%), but neither CT nor ELR consistently improved fruit chemistry. Our results suggest that the number of leaves removed (five) at trace bloom or fruit set was insufficient to induce a carbohydrate-limiting response, as ELR vines did not have lower fruit set or bud fruitfulness. Concurrently, TBLR and FSLR vines did not show recovery mechanisms such as greater production of lateral leaves or higher shoot efficiency. Although the overall level of bunch rot severity was lower than 5%, ELR consistently decreased bunch rot intensity (TBLR, FSLR) and severity (FSLR). TBLR also improved bud freezing tolerance during vine acclimation in both years. CT was the most expensive treatment, and the lack of a consistent improvement in fruit chemical composition or tolerance to winter temperatures indicated that Gruner Veltliner can properly ripen more than one cluster/shoot.

Quality of Wine Grape Cultivars Grown in Czech Republic

This research aims to make an analysis of significant parameters in wine grape from Czech Republic. It was evaluated pH, content of sugar, ascorbic acid, titratable acidity, total phenolic content and texture properties. For analyzes 5 samples of wine grape were used, harvested during the three periods. The results show that during the ripening of wine grapes there were changes of selected qualitative parameters, particularly of total polyphenols, sugar and some varieties of wine grape also ascorbic acid (significantly in the variety ’Gruner Veltliner’, ’Chardonnay’, ’Pinot Blanc’). Pronounced changes qualitative parameters were among wine grapes harvested the 1st and 2nd seasons. Changes in textural properties also occurred during the harvest and for most varieties between 2nd and 3rd period of harvest. The PCA grouped chemical parameters of wine grape in independent sets and can be used as assessment tool of wine cultivars.

Study of rheological behaviour of wines

Abstract This study deals with rheological properties of various wine varieties. Samples of the following wines were used for this experiment: André, Cabernet Moravia, Laurot, Saint Laurent, Gruner Veltliner, Pinot Blanc, Müller Thurgau, and Riesling Italico. These samples were obtained from wine produced from the grapes collected in the Czech Republic (Morava region, subregion Velke Pavlovice). In the first phase, the chemical composition of the samples was determined. The following chemical parameters were determined: total acidity, pH, content of the alcohol, reduced sugars, free SO2, total SO2, and volatile acids. In the second phase of the study, the physical properties of the samples were determined and the samples of the wines were subjected to rheological tests. These tests consisted in determination of apparent viscosity in relation to temperature, hysteresis loop tests, and apparent viscosity related to time. The dependence of the shear rate on the shear stress was described with the Herschel-Bulkley mathematical model. The experiment yielded the following findings: seven out of the eight samples behaved as non-Newtonian fluids at low temperature (5°C); non-Newtonian behaviour was changed into Newtonian at the temperature higher than 10°C; non-Newtonian behaviour was characterised as thixotropic behaviour; the degree of thixotropy is relatively small and reaches 1.85 Pa s-1 ml-1.

Breeding of fungal resistant varieties derived from Grüner Veltliner by chromosomal selection

Traditional cultivar Gruner Veltliner is the most appreciated vine in Austrian viticulture. Due to organic growing the demand for mildew resistance within the same wine profile has increased. Cross breeding can provide such new genotypes which combine traits from different sources by parenthood. Linkage of traits with chromosomes or markers allows to predict some aspects of the phenotype. Equipped with chromosomal assisted selection the development of new varieties could be much easier and faster. On the base of two segregating populations derived from crosses of Gruner Veltliner with Malverina and Seyval blanc we could define correlation of chromosomes with some traits. Mainly ampelographic descriptors and resistance against mildew could be aligned. As a quality parameter of the wine Rotundone analyses were performed and could be attributed to chromosome 5 and 9. Selection supported by the composition of the parental chromosomes enables breeding with some arguments of design. The limits for free choice were the availability of sufficient different genotypes with a broad spectrum of chromosomal combinations. Recently released descendent cultivar Donauveltliner was selected due to the high rate of Traminer alleles.

Influence of Technological Processes on Biologically Active Compounds of Produced Grapes Juices

Grape juice quality can be substantially influenced by different processing methods and their parameters. This study deals with the influence of thermomaceration temperature and its holding time on important juice quality parameters such as the content of trans-resveratrol, trans-piceid, trans-e-viniferin, and 2,4,6-trihydroxyphenantrene-2-O-glucoside. All the aforementioned compounds together with antioxidative capacity, total polyphenols, and antimutagenic activity were measured. This study used the following grapes: Blaufrankisch, Blaufrankisch bio, Saint Laurent, Gruner Veltliner, Gruner Veltliner bio, and Muller-Thurgau. For all tested grape varieties, the most important processing parameters were temperature and thermomaceration holding time. There were no significant differences in the content of the studied compounds. Three preservation technologies, freezing, bottle pasteurization, and high-pressure treatment, were also studied regarding the content of abovementioned biologically active compounds. Results of this study can be immediately applied to grape juice production.

SENZORICKÉ HODNOCENÍ AUTENTIČNOSTI VÍN

The qualitative indicators of wine are also sensoric properties besides analytic properties. The specimens were evaluated immediately after their stabilization. Of course, by the time the sensoric properties are changing and can influence later evaluation, even customers in their desicion for repeating purchase. Specialists evaluated specimen of white wines such as: rhine Riesling, Sauvignon blanc and gruner Veltliner from three locations of Znojmo winery region. All specimen weren´t fermented to dry and they weren´t procesed the same technology, in spite of this, the speciments were evaluated objectively as possilble. The common parameters of vineyards were: exhibition, evaluation above sea-level and average annual temperatrature. The climatic factors had minimum differences in both monitoring vintages of growing season. A different parametr had soils, their geological origin, type of soil, structure and po­wer of topsoil. The acquired results were evaluated and graphically displayed.Gruner Veltliner – specimen No. 1 – this variety was covered in smell and taste by used technology. An outstanding location was a vineyard Weinperky with paleozoic sediments of neogene and higher pH and deeper arable level provides this location incommutable feature in contrast to from other recognizing vineyards of future wine. More likely geological-soil features have even specimens No. 3 and 4, which showed balance characteristic features in recognizing vintage. The specimens No. 2 and 1 had quantity untypical variety shades and they showed balance large differences both in evaluating committees and in recognizing vintages.Sauvignon blanc – the most suitable location was a vineyard Knížecí vrch – a specimen No. 6, which lies on lighter limy soils of Dyje massif together with higher pH created nice feature of variety. A spe­cimen No. 8 had more likely characteristics of location than a specimen No. 6. That express in evaluation. A specimen No. 7 seems less typical and characteristic substitute in evaluation.Riesling rhine – the most suitable location was chosen vineyard Šobes by judges, which gives incommutable features to smell and taste by sandy soils of Dyje massif above river Dyje. A specimen No. 9 represented the smell; specimens No. 10 and 11 were evaluated as average and untypical. They had quite different features in recognizing vintages.The authenticity was extended by sensorial evaluation and at the same time the outstanding locations were chosen, which can give wines of unusual quantity every year in connecting certain variety. The most suitable locations for singular type of wine with extending authenticity are Riesling rhine – vineyard Šobes, Sauvignon blanc – vineyard Knížecí vrch, Veltliner grun – vineyard Weinperky.

EFFECTS OF PROHEXADIONE-CALCIUM ON GRAPE CLUSTER STRUCTURE AND SUSCEPTIBILITY TO BUNCH ROT (BOTRYTIS CINEREA) IN cv. GRÜNER VELTLINER

In Austria plant growth regulators have long been used on grapevines for induction of loose clusters and avoidance of Botrytis cinerea attacks. The purpose of this work was to examine the effect of a plant growth regulator containing prohexadione-calcium as active ingredient based on various parameters. The experiment was conducted on cv. Gruner Veltliner. Results were analysed on the basis of the following parameters, cluster weight and lenght, berry and seed weight, number of berries and seeds, evaluation of infestation severity by B. cinerea, and FTIR analysis. In addition, the bending index of the berries was recorded. which describes the suppleness of the clusters. The four main test variants were: (i) control, (ii) prohexadione-calcium alone, (iii) prohexadione-calcium with a botryticide and (iv) botryticide alone. Regarding the effect of prohexadione-calcium, results showed that there was a significant difference in cluster compactness. The increased number of small clusters additionally resulted in a significant increase in suppleness and reduced compactness. In 2009, B. cinerea infestation in the control was less than in the other treatments; in 2010, no significant difference was found. In 2010, the application of prohexadione-calcium led to increased must densities, compared with the control plots.