National Repository of Grey Literature 8 records found  Search took 0.01 seconds. 
Study of geographical authenticity of Moravian white wines
Horáková, Kristýna ; Křikala, Jakub (referee) ; Diviš, Pavel (advisor)
The aim of this bachelor thesis was to verify geographical autenticity of Moravian white wines based on elemental analysis. This data were completed with the analysis of organic acids, fenolic compounds and atioxidants in wines. There were used two spektrometric methods for the elemental analysis (ICP-MS and ICP-OES). The concentration of organic acids was mesured by Ion chromatography. To determine the concentration of phenolic compounds in wines there was used the high performance liquid chromatography (HPLC-DAD), the content of antioxidants and the total content of phenols was measured on spectrophotometer. In total there were 33 samples of wine from 4 Moravian subregions. For the purpose of determination the samples in groups the dataset was firstly corrected by Grubbs test for remote results. From those data the box plots were created which represents the minimal, maximal and mean concentrations of each measured component. Furthermore the analysis of variance was applied, which picked up 12 statisticly valuable parameters from the whole 47. By appliyng the multidimensional statistical methods (Pearson correlation analysis (PCA) and discriminant analysis (DA)) were compiled mathematical models for the division of Moravian wines according to geographical origin. The success rate of the discrimination test was 96,97%. The cross-validation test showed an 81,82% success rate for classifying unknown samples.
Fenolické látky bielych vín
Šulík, Martin
This bachelor work presents phenolic compounds in white wines.White wine contains lower amount and other groups of phenolic compound compared to the red wine, whic is caused by various content of grapes and also by way of vinification. In literature part is descripted composition and meanig of individual phenolic compounds in regard to difference between red and white wine. Furthermore there is explained mechanism of ensymatic oxidation of phenolic compounds Another section of this work analyzes haze which, formation is connected with higher contain of phenolic compounds. There is descripted not only causes but also mechanisms of forming haze, how to avoid this haze, or how to remove the already formed haze from wine.
Vliv řízené mikrooxidace na technologii bílých vín =: The effect of controlled micro-oxygenation on technology of white wines /
Průšová, Božena
The PhD.-dissertation thesis deals with the effect of microoxidation on white wine technology. The varieties ‚Pinot Blanc‘ and ‚Pinot Gris‘ were used for the experiment in 2016 and 2017. Micro-oxygenation was applied in the first third of the fermentation process and during the maturation of wine. The effect of microoxidation on the course of fermentation was monitored. In micro-oxygenated wines, a statistically significant increase in the number of living yeast was observed immediately after the micro-oxygenation treatment, compared to the control experiment. The increase in cell mass was also observed by measuring the consumption of ammoniacal nitrogen and nitrogen contained in the amino acids. The results of the experiment show a higher consumption of ammonia nitrogen in the micro-oxygenated wine. The amino acid content did not change significantly. During the whole fermentation process, the course of antioxidant activity was monitored. There were no statistically significant differences between micro-oxygenated wines and control, in some cases the antioxidant activity of micro-oxygenated wines was significantly higher. This phenomenon can be explained by the formation of new phenolic compounds, such as gallic acid, which in some cases has been confirmed by HPLC results and theoretically higher production of yeast cell wall breakdown intermediates, which are potent antioxidants. An aromatic profile was determined in the resulting wine by GC analysis and sensory evaluation. Results from GC analysis show higher concentrations of higher alcohols and esters. The results of this experiment from the year 2016 have been successfully published in the reviewed periodical Ciencia e Técnica Vitivinícola: Bozena Prusova, Mojmir Baron, Effect of controlled micro-oxygenation on white wine, Ciencia Téc. Vitiv. 33 (1) 78-89 (2018), DOI: 10.1051/ctv/20183301078.
Možnosti využití dubových náhražek dřevěných sudů při výrobě bílých vín
Spíchalová, Aneta
In the theoretical part of this thesis is mention the history of white wines aged in barrels and composition of wood mentioned. The next part deals, how the wood is processed, and what it consists of before and after toasting. I explore the advantages and disadvantages of using wooden barrels. The practical part deals with adding of staves and chips into fermenting white wine with anticipated results. The experiment was made on two grape varieties. This thesis explores the use of oak staves and chips. The wines were sensorically and analytically evaluated. The wines had antiradicals activities measured. I sum up the results of the experiment in a statistical ending, the conclusion summarized the advantages and disadvantages of using staves and chips in white fermenting white wine.
Role kyslíku při výrobě bílých vín
Sapanelová, Claudia
Oxygen is an important factor active during all winemaking process. It is one of the main agents responsible for the oxidation of must and wine. The exposure to oxygen may have different effects, positive or negative, while it plays an important role in the formation of the organoleptic qualities of wine. In white winemaking, oxygen is known particularly for its negative impacts, especially for the colour browning and the losses of the fruity aroma, often one of the key qualities. White musts and wines are naturally prone to oxidation. This is due to the composition of their phenolic compounds, which are represented primarily by hydroxycynamic acids and their derivates. For this reason the white winemaking process is realised mostly in reductive conditions. Big emphasis is put on the protection against undesirable oxidation, particularly at the begining of the process. Deliberate introduction of oxygen is possible, it may be desirable especially during the alcoholic fermentation, but it has to be always well controlled. In this case, the contemporary winemaking aims to use the techniques of controlled aeration, hyperoxidation and micro-oxygenation respectively. The thesis contains a review approaching the issue, the impact and the management of oxygen in all stages of the white winemaking and present the techniques of controlled aeration and their possible utilization. The experimental part of the thesis is dedicated to the microoxygenation of white wines. Through the analytical comparison, aromatic profile and sensory analysis, of the micro-oxidized wine and the wine prepared in reductive conditions confirms the hypothesis regarding the positive effects of this technique in relation to the organoleptic qualities of wine.
Porovnání komerčně dostupných maceračních enzymů při výrobě bílých vín
Maleňáková, Daniela
This bachelor thesis deals with the influence of macerating enzymes in the white wine production. The use of enzymes, description of pectins and their change during the production of wine, and various types of maceration are described in detail in the literature review. The main aim of this work was to map macerating enzymes commercially obtainable in the Czech Republic and select representative sample for experimental part. Pomace from crushed grapes was divided into 9 batches, treated with enzymes and macerated for 24 hours. The pomace was pressed and stripped subsequently. The yield values, basic parameters and the polyphenolic profile of the must were evaluated for all samples. An evaluation of the enzymes parameters was performed based on these measurements. The results of measurements revealed that the best results were achieved by the Lallzyme Cuvee Blanc enzyme from LALLEMAND company.
Vliv přípravků nahrazujících použití sudů typu barrique na parametry bílých vín
Benešová, Veronika
The literary part of this thesis deals with the production of barrique and their alternatives. The thesis is mainly focused on chips. Additionally there is describes the factores which affecting the chips in wine. More specifically, what are chips effect on the fermentation of white wine. Finaly comparing barrique barrels with chips. The experimental part was based on the experiment, when chips were added to white wine varieties Malverina. Differences beteween variants were in moment of adding (must, wine) and the degreee of tasting (medium, heavy). For evaluate the sensory analysis experiment was attended by an expert team. The tasters rated the sample to a 100-point scoreboard and also to additional table, where they rated specific properities. In the case of variant, when the chips are added to wine, was additionally evaluated certain aromas. Determination of antiradical aktivity was measured by spectrophotometric measurements. Measured values showed that in the case of addition of chips to the must antiradical aktivity was lower than the control sample, probably because of alcohol, whose presence caused leaching of higher amounts of phenolic compounds, antioxidants. The highest antiradical activity showed sample with medium toasted chips.
Možnosti využití dubových parketek při výrobě bílých vín
Spíchalová, Aneta
In the theoretical part of this thesis is mention the history of white wines aged in barrels and the effect of yeast on the wine's aging and he possible technologies. The next part deals with the different kinds of trees, the most popular areas trees come from, how the wood is processed, and what it consists of before and after toasting. I explore the advantages and disadvantages of using wooden barrels, and the differences between different barrels, mainly american and french barrels. I also take a look at making a special piece of wood called staves. The practical part deals with adding of staves into fermenting white wine in half and full amount in comparison with anticipated results. The experiment was made on two grape varieties. The wines were sensorically and analytically.evaluated. The wines had their flavanols and antiradicals activities measured. I sum up the results of the experiment in a statistical ending.

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