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Vliv kvasinkové kultury na aromatický profil bílých vín
Fráňová, Anna
The Diploma thesis deals with the topic of yeasts culture and its influence on aromatic profile of white wines. The first part of the thesis focuses on literature overview, where we can find more details about wine yeasts and its species. The main focus is on possibilities of reproduction these yeasts. The result can be seen on growth curve, which shows the speed and intensity of multiplication of the yeasts. We will see the proces of alcoholic fermentation and determine the difference between spontaneuos fermentation and controled fermentation using special active dry wine yeasts. Smoothly going to second part of literature overview, where we can learn about aromatic properties of wines, especially the aromatic profile that is typical for variety Grüner Veltliner. The beginning of the experimental part will familiarize us with brief description of variety Grüner Veltliner, that were used for the experiment and its origin. Then we can see clear diagram describing the proces of the experiment following the analysis of analytic parametrs. The parametrs are concered about the stum and description of the proces of fermentation of partial variations. In the result part we can find analytical of resultant wines from spectrophotometric apparatuses ALPHA and MIURA and the results of senzoric evaluation done by committee of seven degustators. The final part of the thesis is about comparison of results within discussion and final results listed in the chapter conclusion.
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Porovnání analytických a senzorických vlastností vín před a po sekundární fermentaci
Prokeš, Kamil
This thesis is focused on sensory and analytical evaluation of wines before secondary fermentation (base wine) and after secondary fermentation using immobilized and classic yeast. The theoretical part is described in detail in the process of autolysis of yeast followed by general issues of amino acids, phenolic and volatile conpounds. Attention is also paid to the issue of the influence of amino acids, phenolic and volatile compounds on the composition and analysis of individual components with the influence of sensory perception for sparkling wines. Sensory perception will be evaluated by the hundred-point scale, and using a profile of strength and flavor profile. These evaluations will be compared on the basis of weighted average evaluation by categorization criteria - before and after the secondary fermentation, depending on the type of wine (base wine, wines produced by immobilized yeast and wines produced by classic yeast), according to the sugar content of musts (17, 19 and 21 ° NM) according to the year (2010 and 2011) and according to the variety (Riesling, Pinot Blanc, Pinot Noir, Sauvignon and Gewurztraminer). For this work, the aim was to determine the amino acids and volatile phenolic substances at the base wine, sparkling wine produced by immobilized yeast and sparkling wine produced by classic yeast. All these analytical values will be compared and evaluated according to the above categorization criteria. Subsequently, the data was statistically processed and evaluated in terms of the various influencing factors and their interactions using the graphical representation and interdependence also used Spearmenových correlations. The work found a statistically significant effect of amino acids threonine, serine, aspartic acid, glutamic acid, glycine, alanine, valine, tyrosine, phenylalanine, beta-alanine, beta-aminobutyric acid, arginine and aminoadipic acid to aromatic profile autolyzátové, which is characterized as flavoring butter, brioche and yeast. For phenolics there was no evidence of a difference in their content before and after secondary fermentation. The biggest factors that impact the content of phenolic compounds is the vintage, the grape variety and the sugar content of the must. It was also found to be a negative effect of phenolic compounds (DPPH Trolox, hydroxycinnamic acids, flavan-3-ols with stilbenes) to sparkle sparkling wines. For volatile substances, the hypothesis was confirmed that certain volatile substances are present only in the base wine, or that their concentration after secondary fermentation decreases and the others in turn are represented only by the wine after secondary fermentation or that their representation increases after secondary fermentation. The content of individual volatile compounds depends on the secondary fermentation, variety, vintage and sugar content of the must. The main objective is to compare among themselves and statistically evaluate the effect of amino acids, volatile and phenolic compounds on the evaluation of the hundred-point scale, the profile of strength and aroma profile. According to this inter-comparison of analytical and sensory evaluation we analyzed the effect of amino acids and volatile phenolic substances on sensory manifestation and the resulting quality of sparkling wines. In the sensory evaluation we found a positive statistically significant correlation between effervescence and autolysis aroma in sparkling wine.
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Možnosti vinifikácie fortifikovaného vína
Hanúsek, Martin
The diploma thesis deals with the possibilities of vinification of fortified wine. In the literary part, it deals with the history of the production of fortified wines and describes their basic types. In addition, it explains the individual methods of spirit adding, selection of distillate and conditions for production in Slovakia and the Czech Republic. At the end of the literary section, individual groups of phenolic compounds are described as important compounds contained in fortified wines. In the experimental part, an attempt is made for the Alibernet variety. It was fortified in the beginning, in the middle and at the end of the alcoholic fermentation in two series - must and mash. Complete phenolic substances, titratable acids and pH were measured over three months. The resulting wines were sensitized. All the results were statistically processed and the practice recommendation was then drawn.
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