During the ageing in barrels, the contact with the fi ne 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 SO 2 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 SO 2 -40 mg l -1 , the lees is already able to protect the white wine samples in all aspects. Keywords: sur lie, fi ne lees, reducing agent, polyphenolic compoundsThe sur lie method is a special wine making technology, where the contact between the new wine and the fi ne lees can be taken advantage of. It has a special momentum, namely the battonage, when the wine is stirred periodically in the barrels. This technology originates from France, but nowadays wine makers -in all viticultural areas -use it to widen the white wine assortment. The contact with the fi ne lees plays an important role in traditional champagne production, too (FIA et al., 2016). From the practical point of view, the robust/full bodied wine, which is properly rich in alcohol and acids, is fi t for ageing on lees in oak barrels.The composition of fi ne lees is varying. It contains mainly yeast cells, and in much lower amount, tartaric acid and other organic and inorganic matter. The autolysis is known as a slow process that occurs during the wine ageing period (between 12 to 18 months). So the intracellular compounds, enzymes, plasma membrane, etc., are released just approximately after one year (LAVIGNE et al., 2007;PÉREZ-SERRADILLA & LUQUE DE CASTRO, 2008).It was shown that the resuspension of the lees by stirring (battonage) during the aging period signifi cantly increased the macromolecular extract of the wine (especially mannoproteins, proteins) beside saturated fatty acids and glutathione. The yeast strain, the turbidity of juice during the fermentation, the contact time and temperature also have effects on the migration of the polysaccharides (PÉREZ-SERRADILLA & LUQUE DE CASTRO, 2008).
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 winemaking. 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.Keywords: anthocyanin profile, commercial yeastThe enzyme activity of yeasts might evoke various side reactions (malo-alcoholic fermentation, b-glycosidase activity, tyrosol production, etc). Starter cultures significantly affect the polyphenolic structure, especially in the context of red wine (fermented on skins). The manufacturers and distributers give detailed information about the mechanism attributed to them. Is there any change in the composition and in the concentration of anthocyanins when different starter yeast strains are applied, how do the polyphenol components (catechin, leucoanthocyanins, resveratrol, etc.) change? It is legitimate to ask these questions even if we know that the "gentleness" of the different pieces of wine-making equipment is an important aspect of the amount of the "sediment". Therefore, the effect of several commercially available yeasts, which are recommended for red wine fermentation, on the anthocyanin profile and on other polyphenolic ingredients were examined.The characteristic and the colour of red wines are essentially determined by the amount of red grape pigments (anthocyanins and other phenolic compounds) produced during ripening. In terms of the grape the anthocyanin composition -especially their acylated derivatives -may be characteristic of the variety and the cultivation method (reviLLA et al., 2001), which is only slightly affected by vintage factors. Evidently, the situation is different in the case of wine. During the first third of the technological period of red wine fermentation
The content of 2,3-butanediol ((R,R) and meso isomers) and 1,2-propanediol in grape berries and “liquid samples” (all non-berry extracts) from the Tokaj wine region of Hungary was investigated. Our aim was to find out how the activity of Botrytis cinerea influences the concentrations of these compounds compared with healthy grapes. Based on the measured concentrations, we can make a distinction between healthy berries and noble, rotted, so-called aszú berries. We also investigated if there is a difference between finished aszú wines and liquids intended for aszú production. We wanted to investigate the amount and distribution of the stereoisomers of 2,3-butanediol and their proportions. The results of the HS-SPME-GC-FID analysis of the samples showed significant differences in the 2,3-butanediol content between healthy and botrytised, aszú berries and between liquid samples for aszú production and aszú wines. In the berry samples, meso-2,3-butanediol could not be detected, whereas in the liquid samples, we found good amounts of this isomer. This may be due to the fact that the appearance of the meso form of 2,3-butanediol is a consequence of alcoholic fermentation. Significant differences were found between wines from healthy grapes and wines from botrytised grapes in terms of the levo-2,3-butanediol content, so that from an analytical point of view, a difference can be made between wines from healthy and botrytised grapes. No significant differences were found between berry and liquid samples in terms of 1,2-propanediol concentrations during our tests.
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