No description available.

No description available.

Wine contains organic acids, which determine its final quality. Tartaric and malic acids are found in dominant concentrations. Also present are citric, lactic and succinic acids, and some volatile acids such as formic and acetic acid. The process of winemaking is associated with changes in the concentration of wine acids. The composition of acids in wine is also affected by the type, quality and ripeness of grapes, grape manufacture and wine production. The aim of this study was to analyse the concentrations of tartaric, malic, citric, lactic, succinic, formic and acetic acid during the winemaking process in different press fractions of 8 varieties of white wines from the Vineyard centre Mělník - Chloumek and in 5 commercially purchased red wines, using HPLC with DAD detection, and to analyse the trend of changes in different phases of the winemaking process. The white wine press fractions were supplied following the wine press (A), settling of juice (B), in the phase of partially fermented juice (C) and during the maturation of young wine (D-G.). The samples were taken within 2-3 days. There were no red wine press fractions available from the vineyard. 5 bottles of different varieties of red wine were thus purchased from the shop and analysed. The GraphPad Prism programme was used to perform statistical analyses (ANOVA). The hypothesis suggesting that tartaric acid would be the dominant acid was confirmed in 5 varieties of white wine and in all red wines. The hypothesis suggesting a difference between red and white wines was also confirmed. There were significant differences in the concentration and composition of acids between young white wines and red wines. The hypothesis that the concentration of all acids would increase was not confirmed. Tartaric acid showed the most linear trends of decrease, followed by malic acid. The trend of change in the concentrations of succinic, lactic, citric and formic acid increased in some varieties and it decreased in others. The grape variety, weather during summer and autumn and the manufacturing processes all influence the acid composition in wine. These factors can explain the differences seen between different varieties of wine.

The dissertation thesis focused on investigation of the influence of the leaf area on chosen quality parameters of grapes, on observation of the malolactic fermentation process and possibilities of its control. Literary section of the thesis includes characteristics of individual phenophases of grape wine with emphasis on the changes of substances content of grapes. Mechanism of sugars and acids creation and modification in grapes during ripening is described in detail. Possibilities of leaf area regulation and their influence on substances content of grapes are characterized. Another section deals with biochemical changes during wine production, especially with changes in substances content of wine during malolactic fermentation. The experimental part evaluates the influence of the leaf area on chosen quality parameters of grapes (soluble solids, titratable acids, pH, tartaric and malic acids content) of cultivars 'Pinot Gris', 'Sauvignon' and 'Riesling' in years 2008 -- 2010. The leaf area of each variety was measured in the 1st phase and average leaf area of one bush was calculated. The bushes were treated in three variants with different leaf area. It is obvious that the leaf area of the bush has positive influence especially on accumulation of sugars in grapes. The content of titratable acids in grapes was the highest by the bushes with the largest leaf area, though it was not statistically significant because there were big differences among vintages. The malic and tartaric acid ratio was ambiguous with regard to the leaf area, pH value of musts was ambiguous too. The influence of added pure cultures of lactic bacteria on the malolactic fermentation process was observed on three cultivars ('Blaufränkisch', 'Merlot', 'Cabernet Moravia') in the years 2008 to 2010. The effect of addition of lactic bacteria was observed on 5 preparations (Lalvin 31, BioStar Vitale SK11, Viniflora Oenos, Viniflora CH35 and Enartis ML Silver) and it was compared to spontaneous process of degradation. It was confirmed that the addition of pure cultures significantly accelerates the process of malolactic fermentation, it increases the antioxidant activity of wine, it decreases the production of diacetyl and other carbonyl compounds. Malolactic fermentation caused significant changes in color of biologically degraded red wines.

The aim of this work was demonstrate positive effect of n-3 polyunsaturated fatty acids EPA and DHA on the concentration of plasma triglycerides and cholesterol. According to the hypothesis, these polyunsaturated fatty acids are capable of reducing plasma cho-lesterol in mechanism, where is increased gene expression Insig-1 and simultaneously reduces the expression of genes encoding an enzyme for cholesterol synthesis (3-hydroxy-3-methylglutaryl-CoA reductase, a gene for HMG-CoA-R) and the gene for the LDL receptor, which is responsible for the entry of cholesterol from the plasma into the cells (low density lipoprotein receptor, the density, the LDL-R gene). LDL-R.The experiment was conducted on a model animal (Rattus norvegicus) fed with a standard feed mixture with the addition of 3% of salmon oil, fish oil 6% and 6% of oil from algae of the genus Schizochytrium. The control group was fed a feed mixture with the addition of 6% safflower oil, food with the addition of 3% palm oil was used as a negative control. Each group consisted of 10 animals. From the blood samples was determined levels of total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides. The fatty acid content was determined in muscle, liver and adipose tissue. Food enriched with eicosapentaenoic acid and docosahexaenoic acid led to a reduction in total cholesterol and LDL-cholesterol levels. It was shown (P <0.05) after the addition of fish oil, salmon oil and algae of the genus Schizochytrium oil to feed mixtures of experimental rats, a decrease in total cholesterol (27%, 21%, 27% respectively) relative to controls. Our attempt partially confirmed the hypothesis. At the same time, we found that plasma lipid metabolism affects different mechanism than we thought.

This thesis deals with the evaluation of new growing characteristics PIWI varieties. The main objective was to determine whether the new interspecific varieties from other EU countries suitable for our conditions . Literary section discusses the intersection of interspecific varieties for registration of varieties and of tests for distinctness, uniformity, stability and value. The methodology describes selected varieties Solaris , Aletta , Johanniter , Hibernal , Saphira , Cabernet Cortis , Rösler , which are a prerequisite for its expansion in the country. The experiment was conducted in the vineyards of a private company that has these varieties planted in large areas and wineries already sold on the Czech market. The following describes the analytical method used to obtain the results . These results were summarized in tables and graphs. Based on the theoretical and practical knowledge has been discussed for each variety, their quantitative and qualitative terms.

No description available.

This thesis was prepared at the Institute of Post-Harvest Technologies of Horticulture at the Faculty of Horticulture of the Mendel University in Brno in years 2013/2014. It focuses on the physiological and anatomical descriptions of sensory organs with emphasis on the physiology of taste perception and on methods which are used for sensory analysis of foodstuffs. A section of the thesis speaks about selected organic acids (citric, lactic, tartaric and malic) which were used in it's experimental part. The practical part of the thesis is aimed at researching the influence of various acids on perception of the intensity of acidic taste, by applying the following methods of sensory analysis -- pair test, the graphic scale evaluation method and sequential test. Also the synergetic and antagonistic relations between citric acid, tannin, saccharose and sodium chloride were examined in one of the experiments.

No description available.

The aim of this study was to confirm that the polyunsaturated fatty acids n-3 (n-3 PUFA) have a positive effect on plasma lipids. These acids can reduce cholesterol by increasing gene expression Insig-1 while decreasing the expression of genes encoding Hmgcr and Ldlr. We tested in experimental rats, which were added to the feed mixture of 6 % safflower oil , 6 % fish oil or 6 % of the oil from the algae Schizochytrium. Relative gene expression was Insig-1 in the test group with addition of fish oil to 120% of controls (P<0.05) and in the group with addition of oils from algae Schizochytrium the relative expression of 170 % of control (P<0.05). These results confirm our hypothesis, only a part, as the relative expression of the gene and Hmgcr and Ldlr was in the test group with addition of fish oil 103% (P>0.05) and 101 % of control (P>0.05) and in the group with addition of oils from algae Schizochytrium the relative expression of 117% (P>0.05) and 156 % (P>0.05) compared to control. Thus, to reduce the relative expression of these genes did not. However, we have shown that n-3 PUFA contribute to a reduction in plasma cholesterol and in this case up to 20 % of control. The concentration of cholesterol in the group with addition of safflower oil was 1.35 mmol.l-1, the group with the addition of fish oil 0.98 mmol.l-1.