Grape canes are a waste product from viticulture that show potential as an industrially extractable source of stilbenes, which are valuable for medical and other purposes. In this work, grape canes collected in three consecutive years (2014–2016) at six different places in South Moravia, Czech Republic were extracted, and the contents of trans-resveratrol, trans-ε-viniferin, and r2-viniferin were determined by high-performance liquid chromatography. The study included three blue grape varieties of Vitis vinifera L. (Cabernet Moravia, Blaufränkisch, and Piwi variety Laurot) and four white grape varieties (Chardonnay, Green Veltliner, Piwi variety Hibernal, and Piwi variety Malverina). From the viewpoint of producing extracts with high stilbenes content, the Hibernal variety is clearly the best. The mean amounts of the stilbenes for this variety at all localities and for all three years were 4.99 g/kg for trans-resveratrol, 3.24 g/kg for trans-ε-viniferin, and 1.73 g/kg for r2-viniferin. The influence of vintage, locality, and variety on the amounts of stilbenes was studied using PCA analysis. In contrast to expectations, there was no strong impact of locality on stilbenes content. The differences were varietal for most varieties, regardless of the area of cultivation. Laurot and Hibernal varieties did differ significantly in that respect, however, as they exhibited clear dependence on location.

Abstract:A method for identification of highly fluorescent compounds in vine leaves infected by Plasmopara viticola was developed using reversed phase liquid chromatography with simultaneous diode array and fluorometric detection. Fluorescent compounds were extracted from leaves with a methanol-water mixture (70:30). Separation by HPLC was performed using a C 18 column and gradient elution with water-acetonitrile mixtures (20-80% of acetonitrile). The main unknown fluorescent compound was identified by line spectral comparison with a standard obtained by UV photoisomerization of trans-resveratrol glucoside, and its structure was confirmed by liquid chromatography-mass spectrometry. Identification and structural elucidation of the fluorescent compound in the leaves of Vitis vinifera allows early detection of Plasmopara viticola invasion.

This work is aimed on stopping of alcoholic fermentation to leave residual sugar and the possibility of sulfur dioxide reduction in wine technology and storage. As a very good opportunity showed mixture of higher saturated fatty acids with a reduced dose of sulfur dioxide. Experiments have confirmed that the concentration of viable yeasts in 1 ml of wine for variants treated with a mixture of fatty acids is significantly lower than in variants treated with sulfur dioxide alone. Then was monitored the influence of fatty acids on stored wine with residual sugar. At this point a dramatically prolongation of interval to secondary fermentation (depreciation of wine) in the bottle was confirmed. Finally, attention was paid to influence on the organoleptic characteristics of wine treated this way. In this case, it is possible to consider the recommended concentration of fatty acid below the threshold of susceptibility.

The designation of traditional varieties of grapevine is usually based on verbal information or very dated records. Old rare cultivars found in the Czech Republic were identified by Simple Sequence Repeat (SSR) analysis, a generally accepted method for cultivar identification. These cultivars are primarily maintained in a national collection of genetic resources. Finally a total of 102 candidate genotypes was selected where 49 traditional varieties were identified on the base of nine SSR loci compared with the European Vitis Database. Thirty-six items were registered under the correct designation. The remaining genotypes included four clones, and two genotypes could be described as synonyms. Seven genotypes were found to be incorrectly marked. For three of them, the correct name was found in the database under their SSR profile and four items were considered to be unique as no identical profile was found.

Grape phenolics are considered to have a significant impact on wine quality, with their quantity and dynamics being strongly influenced by environmental conditions. We investigated the effect of ambient sunlight on the temporal dynamics of phenolics in cv. Chardonnay under field conditions during the 2012 ripening season, from véraison until harvest. The phenolic profiles of the grapes were monitored at predefined time intervals by using high-pressure liquid chromatography (HPLC) and spectrophotometric (OD) analysis. The obtained concentrations were correlated with the average sunlight intensities preceding the sampling. No significant correlations were found between the hydroxycinnamic acid, hydroxybenzoic acid and stilbene content, in contrast with the strong relationships found between: (i) OD 280 nm , (ii) catechin, (iii) flavanols and (iv) total polyphenols and the fluctuating dose of ambient sunlight reaching the grapes throughout the ripening season. The light-dependent dynamics of several main phenolic compounds in cv. Chardonnay during the ripening period could help to establish correlation models that increase the applicability of meteorological data in the assessment of optimal phenolic ripeness in modern viticulture.

Response of grapevine leaf tissue naturally infected by Plasmopara viticola in field was measured by means of chlorophyll fluorescence and reflectance signals. Three susceptible grapevine varieties (Cabernet Sauvignon, Pinot Blanc and Pinot Gris) were used in this study. Since the infection impairs photosynthetic activity, distribution of FV/FM parameter (maximum quantum yield of Photosystem II) over the leaf was effective to discriminate healthy and naturally infected leaf tissue. FV/FM was reduced ~ 25% in all infected leaf parts. Infected leaf spots expressed significantly altered chlorophyll fluorescence induction kinetics expressing much slower electron transport rate both on donor and acceptor site of PSII. Vegetation reflectance indices followed the variations in pigment content after the fungal infection. R750/R700 (R2 = 0.877) and CRI (carotenoid reflectance index; R2 = 0.735) were the most potent to follow changes in chlorophylls and carotenoids contents, respectively. Infected leaf tissue exhibited decrease in chlorophyll a (~50 %) as well as carotenoids (~70%). We conclude that combination of chlorophyll fluorescence and reflectance measurements can be used as an effective non-invasive tool for an early detection of Plasmopara viticola in field as well as for estimation of the level of infection.

Téthal J., Baroň M., Sotolář R., Ailer S., Sochor J. (2015): Effect of grapevine rootstocks on qualitative parameters of the Cerason variety. Czech J. Food Sci., 33: 570-579.The Cerason variety is a hybrid from the cross of Merlan × Fratava varieties and its registration took place in 2008. In the category of fungus-resistant (PIWI) grapevine varieties, Cerason represents a very prospective variety. This study deals with effects of seven selected rootstock varieties (K 125AA, Amos, Börner, CR2, K5BB, K1SO4, and T5C) on qualitative parameters of Cerason juice. This experiment was established in 2011 in vineyards of Mendel University in Lednice. In the juice of the berries, the following parameters were monitored: concentrations of sugar, total acids, tartaric acid, malic acid, ratio of tartaric to malic acid (β-ratio), concentration of yeast assimilable nitrogen, and pH value. These parameters were monitored in seven-day intervals in the period of 6 weeks. The aim of this study was to identify those rootstock varieties that would be the most suitable for the given locality on the basis of contents of the aforementioned important substances. The best results were recorded in K125AA and K5BB rootstock varieties.

Vliv kvasinek na aromatický profi l vín z kabernetových odrůd révy vinnéKlíčová slova: kvasinka, aromatika, kabernetová odrůda ■ 1 ÚVOD V poslední době jsou v oblibě lehčí, ale dostatečně strukturní čer-vená vína s výraznější aromatikou po původní odrůdě. Je to dáno tím, že většina našich vinařství vyrábí právě taková vína, určená ovšem pro rychlý prodej a nikoli pro archivaci. Na trhu existuje také nepřeberné množství fi rem, nabízející aktivní suché vinné kvasinky (ASVK) určené k výrobě právě takových vín. Nicméně producentů, kteří tyto kvasinky selektují, zase tolik není, a tak v balíčcích o růz-ných názvech kvasinek se prodává jedna a ta samá kvasinka od stejného výrobce, ale jiného prodejce. Výsledkem jsou pak ona ovocná a mnohdy charakterově velmi podobná uniformní vína. A právě i z tohoto důvodu některá vinařství začínají více využívat vlastní zákvas kvasinkami z vlastní vinice (připravený zákvas) nebo spontánní fermentaci pro podtrhnutí autenticity takto získaného vína.Spontánní kvašení s sebou nese hned několik rizik. Recently, the popularity of lighter, but enough structural red wines with expressive varietal aroma has been increasing. This is due to the fact that most wineries produce their wines using a universal or very similar yeast. There were three varieties chosen for the experiment. All the varieties have very strong varietal character -the Cabernet type, namely 'Cerason', 'Cabernet Moravia' and 'Cabernet Sauvignon'. The musts from these varieties were inoculated with three most commonly used active wine yeast (+ spontaneously fermented control variant), which are recommended to emphasize the varietal aroma in the wines. After six months, the sensory analysis took place and all the obtained results were statistically processed. All tested ADWYs showed positive preferred properties -fast onset and short fermentation time, highlighting the varietal character and strength of the wine over control. Nevertheless, we can state that the most suitable yeasts for ´Cabernet-like´ cultivars (such as CS and CM) were Cépage Collection Cabernet and Fermicru XL, whereas for fruitier cultivars (like Cerason) the best yeast choice was Oenoferm Rouge or Fermicru XL. Sotolář