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During the course of research, the extractability of various phenolic compounds were analysed in ‘Blaufraenkisch’ berry skins and wines produced by six types of vine load. A sample of the berry skin was detached from the harvested crop and following the extraction with hydrochloric acid-methanol the composition of the extractive and the wines prepared by microvinification was analysed. During the course of the tests, the total polyphenolic-, anthocyanin-, leucoanthocyanin- and catechin content of the samples were measured by the application of the spectrophotometric method. Based on the measured data, the extraction coefficients (EC %) were calculated for each vine load, and then through the application of statistical methods, the data of three vintages were evaluated. The results revealed that extractability does not necessarily depend on the method of cultivation or the vine load. No significant differences were found pertaining to either the extractability of the total polyphenolic-, leucoanthocyanin- or catechin content. However, the extraction coefficient of the anthocyanins in crops produced by cluster selection and cane-based cultivation was significantly lower than in the cluster-selected crops of vine-stocks with less bud load.

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Skin-contact fermented white wines, the so-called orange or qvevri wines, have been gaining international attention from winemakers, importers, sommeliers, consumers, and journalists over the last 10 years. Sommeliers are now regularly pairing orange wines with fine cuisine. This new culinary trend is part of a general move by the consumer wishing to respect the existence of traditions and innovation, combined with a growing interest in environmental awareness and healthy options. Orange wines are made from white grapes using ancient Georgian techniques. The essence of this method is the long skin-contact fermentation in amphorae without any chemicals or specific yeast. In our work, the polyphenol content of orange wines, in particular total polyphenol and catechin content, as well as colour intensity were measured to ensure safe winemaking technology without oxidized components.

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The sensory quality of red wines is basically determined by the colour, which depends on the amount and on the evolution of anthocyanins and other phenolic compounds extracting from the berries into the wine during wine-making. The anthocyanin-monomers are responsible for the development of the red colour, and their acylated derivatives provide stability for the colour of the wines. The anthocyanin profile of wines is affected by several factors: the grape variety, the conditions during wine-making, and also the yeast culture used for the fermentation. In our experiments a self-compiled model solution was fermented by spontaneous fermentation, as well as by four commercial yeasts under laboratory conditions. After fermentation total polyphenolics, anthocyanins, anthocyanin monomer profile, colour intensity, hue, and the ratio of polymeric anthocyanins were studied. Our results show that the spontaneous yeast fermentation resulted in a higher anthocyanin concentration in the fermented model solution, but the commercial yeast strains provided a more advantageous colour characteristic compared to the spontaneous fermentation. After the spontaneous fermentation less sediment was left than in the commercial yeast fermented samples.

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While keeping wines on the fine lees the composition of nitrogen-containing substances, including the amino acid concentration, changes as a result of the autolysis of yeasts. During the course of former experiments, it was proven that yeasts were able to reduce the polyphenolic composition of wines. As part of the research for the present publication, the change of polyphenolic content in ‘Chardonnay’ wines kept on the lees was analysed. In addition the quantity of tyrosol, required for the forming of simple phenolics, was examined. The results proved that yeasts reduced the quantity of polyphenolics. In addition, due to the increased amino acid concentration, yeasts reduced the quantity of tyrosol that is derived from the amino acid called tyrosine.

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Acta Alimentaria
Authors: M. Stéger-Máté, G. Ficzek, E. Kállay, G. Bujdosó, J. Barta, and M. Tóth

The variation of some compositional quality parameters in connection with ripening time in the case of four sour cherry varieties ( Prunus cerasus L. Mill.) was studied. Our aim was to optimize the harvest time on the basis of antioxidant capacity. The experiments were carried out in the Érd-Elvira orchards of the Research Institute for Fruitgrowing and Ornamentals (cultivars Érdi bőtermő, Kántorjánosi 3) and in orchards of the Agárd Frucht Ltd. in Agárd (cultivars Érdi jubileum, Maliga emléke). Anthocyanin, polyphenol and vitamin C contents as well as the water-soluble dry matter content of fruits were measured.According to the results of quality parameter measurements it can be stated, that in case of the studied cultivars the optimal picking time for industrial processing is the second picking. At this time the anthocyanin, polyphenol and water-soluble dry matter content of the cultivars are optimal. In general, at the end of the ripening period the fruits shrink, fruit weight and juiciness decreases as a consequence of water loss, therefore determining optimal harvest time for the desired utilization purpose is very important. According to our results, out of the four studied cultivars, Érdi jubileum has the highest values regarding anthocyanin and polyphenol contents.

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During the ageing in barrels, the contact with the fine lees triggers several processes in wine. Lees has a reductive effect by absorbing dissolved oxygen and reducing the amount, which will remain in the wine. At present, minimizing the addition of sulphur dioxide is the trend in all viticultural areas. In this study, the effect of various sulphur dioxide levels was monitored in presence of the lees to determine which dose is appropriate to provide the protection of susceptible white wine against oxidation.

Without SO2 protection, the rH and redox potential changed slightly, so the level of dissolved oxygen seemed to be controlled during the ageing period by the lees, though the antioxidant effect of lees in itself was not appropriate to protect the polyphenol content from chemical oxidation, which led to considerable browning. With the addition of a lower amount of SO2 — 40 mg l2, the lees is already able to protect the white wine samples in all aspects.

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Polyphenol compounds in grapes and wines are of paramount importance: they have a key role in determining wine quality, and also the beneficial health effects of moderate red wine consumption are well-known. The polyphenol concentration of wines is determined mostly by: a) their concentration in the grapes and b) the production technology, particularly the time and type of aging. Our goal was to determine the trans-resveratrol and anthocyanin contents of Hungarian red wines under different manufacturing conditions, by monitoring the 24-month aging process – using barrique and oak barrels – with semi-annual sampling, without considering vintage. We have chosen to determine polyphenol components that could originate from either the grapes, or be produced during the wooden barrel aging. Both the aging time and the wine variety had non-negligible effects on the changes in the concentrations of the studied components, whereas the wooden barrel type had not.

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