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Influence of grapevine growing methods on quality of wine
Šprláková, Katarína ; Hrstka, Miroslav (referee) ; Vránová, Dana (advisor)
This thesis is concerned about the impact of ecological and integrated cultivation of vines for wine quality. The theoretical part describes the history, characteristics of the vine, the conditions that can affect the quality of grapes and the finished product. This work also describes the chemical composition of the fruit of the vine, the base phase of processing of grapes and wine production, from cider pressing to bottling processes and analyzes the chemical composition of wine. In the experimental part are monitored changes of chemical parameters (dry matter, alcohol, total and reducing sugars) in the musts during the process of fermentation. The musts come from grapes of Rulandské modré grown in a system of integrated and ecological production.
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Chemical and sensory analysis of fruit juice from selected cultivars of European elder
Ješková, Kristýna ; Vespalcová, Milena (referee) ; Hrstka, Miroslav (advisor)
The aim of this thesis is the chemical and sensory analysis of the juice from fruits of cultivated varieties of elderberry (Sambucus nigra L.). In the theoretical part botanical description of elderberry including its distribution and places of existence are given. There are also mentioned medical effects and collection of various parts of the elderberry as well as breeding certain species and methods evaluating sensory features of the juice samples prepared from the cultivated varieties of elderberry. In the experimental part some chemical parameters (yield, soluble dry matter content, relative density, pH, titratable acidity, formol number, reducing saccharides) in the juice of berries of eighteen cultivated varieties of elderberry were determined. In fifteen cultivated varieties was made sensory evaluation using profile test and scale. The aim of the evaluators in the evaluation using scale was to evaluate the taste, smell, sensory quality and preferences according to seven point cathegorical hedonic scale. In the profile test, five point scale was used to evaluate the intensity of chosen flavours: acidic, sweet, bitter and others. Overall impression of the sensory evaluation was rather not positive. In majority of the samples the taste and smell were evaluated as good or satisfactory and their general acceptability, too. The juice from the wild elderberry was estimated as worse than in other samples, its taste, smell and overall acceptability were unsatisfactory. In majority of the cultivated varieties were the taste and smell estimated as unsatisfactory as well as their general acceptability.
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Sensory quality of fruit juices
Hamalová, Veronika ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This Bachelor‘s thesis deals with the evaluation of sensory quality of orange juice from different producers. All selected samples were made from concentrate. In total five samples bought in Tesco Stores CZ in Brno were evaluated The theoretical part focuses on the composition and properties of orange and orange juice, and their production technology. The selected methods for sensory evaluation of foods are mentioned. The definition of orange juice according to Czech Standard 56 8541 is also presented in this part. The appearance, color, taste, smell and consistency were evaluated using ordinal scales, taste development using graphic scale. The ranking test was also included. Written results were graphically evaluated and statistically treated.
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Representative of small fruit - gooseberry and its nutritional characteristics
Mohelský, Tomáš ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals with less known fruit - gooseberry (Ribes uva-crispa). The theoretical part describes the botanical characteristics of gooseberry: description of plant breeding and plant forms. Then selected varieties, pests and diseases of gooseberry are described. The following chapters include a list of active substances in the gooseberries and its treatment. In conclusion, the theoretical part describes the most common methods for the determination of pectin in fruit. The experimental part deals with the optimization of spectrophotometric methods for the determination of pectin and determination of pectin itself in gooseberry.
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Determination of Rubisco enzyme content in leaves
Hlaváček, Viliam ; Vránová, Dana (referee) ; Hrstka, Miroslav (advisor)
The aim of the bachelor thesis was to optimize the conditions of the Rubisco enzyme quantity determination by the SDS-PAGE method and the determination of appropriate protein extraction method from plant tissue. Also the concentration range for which the method is linear was determined. Gels with different density ran under different voltages during the electrophoresis were tested for the aims of optimization. Also two different protein extraction methods were used. These were direct extraction to TRIS buffer and extraction with TCA/acetone method. The best results were obtained with protein separation on 8% gel and voltage of 90 V, while the volume of loaded sample was 5 µl. Under these conditions was the Rubisco great subunit band enough separated from the other protein bands, so that the densitometric evaluation provided better quality peaks with good baseline. The linearity of method under these conditions was in concentration range 0,125–1,0 mg of enzyme in 1 ml of sample. Direct extraction of the enzyme with TRIS buffer was less effective than the precipitation of proteins with trichloracetic acid in acetone followed with dissolution of the precipitate. The best buffer for the protein pellet dissolution was the thiourea buffer prepared according to Amalraj et al. [17]..
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A study of the stress distribution around the bimaterial notch tip
Hrstka, Miroslav ; Klusák, Jan (referee) ; Profant, Tomáš (advisor)
Presented bachelor’s thesis deals with determination of stress singularity exponent, by which is possible to completely define the stress distribution around the bimaterial notch tip. This task is divided in four parts. The first part concerns with basics of fracture mechanics, concretely linear elastic fracture mechanics of crack and Irwin’s conception of stress intensity factor. The second part deals with generalizing of linear fracture mechanics to notches. In the third part is initiated the numeric-analytical algorithm for computation of stress singularity exponent and determination of strains and stresses of given notch, which is compounded from two orthotropic materials. The last part is created by numerical example, in which the concrete configurations of notches are tested in calculating software.
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Diurnal changes of Rubisco activity under ambient and elevated concentrations of carbon dioxide
Uhrová, Lucie ; Vítová, Eva (referee) ; Hrstka, Miroslav (advisor)
Diurnal changes of Rubisco activity under the impact of ambient (380 µmol mol-1) and elevated (700 µmol mol-1) concentrations of carbon dioxide were studied in beech (Fagus sylvatica). Samples from leaves were taken in the two-hour intervals from 4:00 to 21:30 on the 22. 7. 2009 and activity of Rubisco was determined spectrophotometrically. No statistically significant differences were found between Rubisco activity of leaves growing in ambient and elevated CO2 concentrations. No increase of Rubisco total activity after daylight shows that nocturnal inhibitor CA1P is not present or plays only negligible role in beech. During the day Rubisco activity showed only statistically insignificant deviations. A slight decrease of Rubisco activation state in the afternoon indicates the afternoon depression of Rubisco initial activity.
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Characterization of elder juice on the basis of some chemical parameters
Mizerovská, Lucie ; Vespalcová, Milena (referee) ; Hrstka, Miroslav (advisor)
The aim of this thesis was to determine selected chemical parameters of elderberry juice namely its wild variety and four cultivated types Albida 08, Albida 09, Dana and Haschberg. The relative density was the lowest for cultivar Albida 09 (1.0149) and the highest for the wild variety of elder from the surroundings of Padochov (1.0337). Values of pH ran within the range of 3.62 for cultivar Haschberg to 4.85 for cultivar Albida 08. The highest titrating acidity was determined by cultivar Haschberg (13.12 g l-1), the lowest content of acids was determined by cultivar Albida 08 (3.47 g l-1). The highest content of reducing sugars had cultivar Albida 08 (9.64%) together with the wild variety of elder from the surroundings of Padochov (9.47 %), the minimum amount of sugars was determined by cultivar Dana (4.79 %). The content of citric acid varied between 4.76 g l-1 by cultivar Dana and 13.48 g l-1 by cultivar Haschberg. The total amino acid content, expressed as a formole number, was the lowest in cultivar Haschberg (12.9) and the highest in the wild variety of elder from the surroundings of Padochov (59.2).
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