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Changes of aroma active compounds during production of model cheese
Školová, Dominika ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
The aim of the work was identification of aroma active compounds in Moravský bochník cheese type, than discuss their changes during ripening and consider influence of aplication different rates of microbial cultures on number of volatile compounds. SPME-GC-MS was used for identification of volatile compounds. In total, 148 of volatile compounds were identified and 82 of them are considered as aroma active compounds. Three microbial cultures (their combination with predominant thermophilic or mesophilic culture) were used for making samples. The influence of predominant thermophilic/mesophilic culture on number of volatile compounds was not proved. From the point of view of sensory quality, combinations with predominant mesophilic culture proved to be more successful. During ripening, the number of identified compounds was reduced in all the combinations of cultures studied. The optimal time for ripening seems to be three months.
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Aroma active compounds of selected types of medical herbs
Pecinová, Ester ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This thesis deals with aroma active compounds of selected types of medicinal herbs, specifically lavender (Lavandula officinalis), peppermint (Mentha piperita), sage (Salvia officinalis), St. John’s wort (Hypericum perforatum) and hyssop (Hyssopus officinalis). In the theoretical part the single herbs were characterized including botanical description, chemical composition, medicinal properties, adverse effects and the practical use; aroma active compounds present in herbs are also emphasized. Based on the literature search, gas chromatography coupled with mass spectrometry as currently the most frequently used method, was chosen for the assessment of aroma compounds. Solid Phase Microextraction was used for isolation of volatile compounds from dried herbs. Within experimental part of the work selected parameters of the SPME-GC-MS method were optimized, aroma compounds in samples of herbs were identified, and twenty four suspected fragrance allergens due to the Regulation (EC) N° 1223/2009 were also identified and quantified. Overall 69 compounds were indetified together with 2 allergens in lavender, 59 compounds including 5 allergens in peppermint, sage contained 49 compounds with 4 allergens included, 41 compounds were identified in St. John’s wort including 4 allergens and finally 64 compounds with 4 allergens included in hyssop.
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Neuroactive steroids in human physiology and pathophysiology
Kubátová, Jana ; Hill, Martin (advisor) ; Fanta, Michal (referee)
The present diploma thesis is focused on the evaluation of steroid metabolome in body fluids in human pregnancy and parturition and also concentrates on the estimation of steroids in men with epilepsy (MWE) regarding the influence of epilepsy and its treatment with antiepileptic drugs (AEDs). The results obtained eventuate to the following conclusions: 1. They support the proposition about the key importance of corticoliberin for the timing of human parturition via stimulation of the steroidogenesis in the fetal zone of the fetal adrenal (FZ). Changes in steroid levels, however, much better predict the timing of parturition than the variation in corticoliberin. 2. The distribution of isoforms of placental oxidoreductases determines the excess of oxidized forms of the sex steroids and NAS in the fetus and the excess of their reduced forms in mother. This mechanism fundamentally affects the steroid bioactivity. The results indicate the role of NAS in pregnancy sustaining, their analgesic effect around parturition and their role in the pathophysiology of postpartum blues.
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Comparison of HPLC a GC-MS method for pesticide determination in soil
Chalbia Václavíková, Alena ; Kočárek, Martin (advisor) ; Havlík, Jaroslav (referee)
Physical and chemical properties of pesticides may vary significantly. Pesticides can be acidic, neutral or alkaline. Some compounds containing phosphorus, other sulfur, nitrogen or halogens. These atoms can be important for the detection of pesticides. Some of the compounds are volatile, others on the contrary not evaporate, which is also one of the important properties for chromatography. The diversity of pesticides actually makes it impossible to create a universal method, which is very impractical in terms of quality and time determination. Because that pesticides are one of the most chemicals in most countries. In the food and drinking water are limits on pesticides in order to avoid negative impact on public health. For residues in soil or surface water limits are set. (Lutz et al., 2006)
The objective of this thesis is to evaluate the possibility of using two types of chromatographs with different detectors for the analysis of pesticide. Pendimethalin which was chosen for this work, will be analyzed usinga liquid chromatograph with UV detektor and gas chromatography with mass detector. Both this method will be compared as well two extraction methods (Soxhlet extraction and shaking), and two extraction agents (methanol and acetonitrile).
Another point of the work is to provethe hypothesis that, for the determination of pendimethalin in soil is by gas chromatography using a mass spectrometer in comparison with the high performance liquid chromatography time and more expensive, but will achieve a higher yield and a lower detection limit of the pesticide.
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Monitoring of Volatile Compounds in Dry Dog Foods
Šímová, Lenka ; Nový, Pavel (advisor) ; Adéla, Adéla (referee)
The aim of this study was to explore the influence of volatile compounds in dry dog food on its attractiveness for dogs. The assumption was that the attractiveness is mainly affected by volatile compounds presented in the feed.
This study brings overall information about dog´s digestive system and its nutritional requirements with the summary of available feeds including the production process and list of the customary ingredients. A survey of the most common volatile compounds including appropriate analytical methods is also part of this study.
A feed preference test was performed in experimental part of this study. The preference ratio of two dry dog diets was set to 21:79 % that shows clear preference for one of the feeds.
Chemical analysis using gas chromatography-mass spectrometry revealed distinctions in the volatile compounds profile of the tested feeds. 3-tert-butyl-4-hydroxyanisole that is part of synthetic antioxidant BHA was identified to be the main volatile compound that could possibly be responsible for feed preferences observed in this study.
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Synthetic aromatic substances in wastewaters
Tylichová, Petra ; Čáslavský, Josef (referee) ; Vávrová, Milada (advisor)
Synthetic fragrances are artificially synthetised organic compounds which are used as fragrant substances in assorted personal care products, perfumes, cosmetics, soaps, detergents, cleansing articles, etc. So-called musk compounds creates significant group of synthetic fragrances which are distinguished by specific fragrance reminiscent of musk. Recently great attention is devoted to musk compounds because they were proved in different units of environment. The aim of diploma thesis was determination of selected linear musk compounds (arocet, aroflorone, linalool 925, lilial, isoamyl salicylate) in real samples of waste water in the influent and effluent from the sewage treatment plant Brno-Modřice. At first optimization of selected method was performed and then this method was used for own determination. Analytes were extracted by solid phase microextraction (SPME) from sample. Method of gas chromatography with mass spectrometry was used for own analysis. The results were used for evaluation of efficiency of removing linear musk compounds from waste water.
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Determination of residues of the selected pesticide effective substances in wine using the GC/MS method
Ehrenbergerová, Martina ; Benešová, Karolína (referee) ; Mikulíková, Renata (advisor)
The grape is one of the oldest cultivated plants. It can be consumed as a fruit or it can be used as a raw material for making stews, juices or the cultivated drink – wine. Generations of wine-makers have been striving to improve both the cultivating conditions of vineyards and the quality of wine. Many harmful elements, such as herbivorous pests, diseases and storms are important factors that can have a negative impact on crop quality. To regulate the effects of these factors, an integrated protection system is used, incorporating agronomical measures, resistant varieties and a wide spectrum of pesticides. However, increasing the usage of pesticides brings certain dangers to both the production quality and the environment. This necessitates the monitoring of the negative effects, including the content of pesticide residues in the grapes. My thesis studies and experimentally assesses selected pesticide residues in certain wine samples.
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Study of volatile hydrocarbon decomposition in non-thermal plasma of gliding arc at atmospheric pressure
Töröková, Lucie ; Rašková, Zuzana (referee) ; Kozáková, Zdenka (advisor)
Diploma thesis deals with gliding arc discharge in non-equilibrium plasma, its properties and usage for dissociation of volatile organic compounds. Plasma techniques create a perspective alternative to classical methods such as adsorption, biofilters, thermal processes, freezing and condensation. The method used for analysis of dissociation products is described in the theoretical part as well. Method is gas chromatography and it is combined with mass spectroscopy. The experimental part contains the overall description of GlidArc reactor where volatile organic compounds were dissociated. The volatile organic compound is brought into the reactor from the reservoir by carrier gas (nitrogen); synthetic air was used as working gas. The reactor is connected to the device for sampling. This device has several openings for sampling by SPME fibre method, sorption tubes method and a special opening for probe entry from the device Testo 350 M/XL, which enables instant analysis of low-molecular compounds. GC-MS was used for determination of high-molecular products of dissociation. Products sorbed on SPME fibres were analysed directly, compounds sorbed by active carbon were extracted by carbon disulphide. Samples obtained using SPME fibres were analysed. The major products of the dissociaton were found due to this analysis, those major products are in the case of hexane: pentanal, 4 methyl-3-pentanal, 2-butoxy-ethanol, pentane a 2-hexene. Major products detected when dissociating cyclohexane were: l,3-dimethyl-butane, propanal, cyklohexanone, 5-hexenal a 2-pentyn-1-ol. Major products of xylene dissociation were methyl-benzene, benzaldehyde, 4-methyl-benzaldehyde, 1-nitroethyl-benzene a benzenmethanol. After analysis obtained using sorption tubes showed that mainly the dissociated compound was sorbed, but the products of the dissociation were presented in too low concentration for an adequate analysis. For that reason the sorption tubes were used only for quantitative determination of the compounds depending on the power supply. The dependence of the dissociation of the compounds on the power supply was observed using SPME fibres which were used for quantitative determination. The Results obtained by both obtained techniques were almost in accordance. Speaking of low-molecular compounds, dissociation of all compounds gave the same products, i.e. carbon dioxide, hydrogen, nitrogen oxide, nitrogen dioxide and water. The results show that the dissociation of VOC gives - besides many potentially dangerous dissociation products - significant amounts of nitrogen oxides which is harmful to the environment. Hence it is necessary to be concerned with problems studied in the future mainly with respect to limitation of NOx generation. It will be possible to optimalize the conditions of the VOC dissociation on the basis of future kinetic analysis.
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Study of volatile hydrocarbon decomposition in non-thermal plasma of surface discharge at atmoapheric pressure
Věrná, Jana ; Rašková, Zuzana (referee) ; Kozáková, Zdenka (advisor)
The main goal of this thesis was to study plasma generated by surface discharge and its application in volatile organic compound destruction. Introduction of this thesis deals with the issue of volatile organic compound. The term of volatile organic compound was defined and explained. Summary of the most important sources of volatile organic compound emissions and possible technics for their elimination was presented. This thesis drew attention on negative aspects of volatile organic compounds on human organism and on the whole environment. The problems of surface discharge and its possible application in various branches are known only few years therefore construction of plasma reactor itself was the first independent step of this work. The plasma reactor was consisted of electrode, which was created from the series of metal stripes each other separated by dielectric barrier. On the surface of the electrode, discharge was regulated and distributed. For the reason of technical limits experiment time was limited up to one minute. The experimental part describes reactor for surface discharge and other parts of apparatus in which degradation volatile organic compound was carried out. Nitrogen was used as carrier gas and it was mixed with air before entering into the reactor. Samples of compounds after degradation process were taken from reactor for the subsequent analysis. Analysis of the products proceeded in a gas chromatogram linked to mass spectrometer. The decomposition products were adsorbed in the SPME filaments or in sorption tubes. The decomposition products were analysed also through the mean of Testo 350 M/XL. This apparatus provided the information on the concentration of small molecules such as CO, H2, NO, NO2 and CxHy Hexane, cyclohexane and xylene were used as VOC examples. Analysis of GC-MS showed decomposition products of hexane, cyclohexane and xylene. The decomposition products were especially various alcohols, ketones, aldehydes and benzene compounds. The apparatus Testo 350 M/XL was unable to detect any CxHy, only large quantity of NO2. This thesis was further focused on possible factors which could have an influence on degradation of compounds, for example input power or different flow of oxygen. It was found that increasing power declined the removal efficiency. The maximum removal efficiency was 87 % for degradation of hexane at the lowest input power. Next part of this thesis was focused on diagnostics of plasma generated in the surface discharge form. The optical emission spectroscopy has been chosen as the best method for plasma characterisation. By this method, various important discharge parameters can be determined, e.g. vibration and rotation temperature. The obtained numeric value of rotation temperature was 840±80 K and vibration temperature was 1880±140 K. The obtained results may be used as a fundament for further study of VOC decomposition in surface discharge.
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