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Preparation and characterization of Echinacea extracts
Pallová, Jana ; Veselá, Mária (referee) ; Vítová, Eva (advisor)
Echinacea purpurea is a rich source of biologically active compounds, which are attributed to several therapeutic effects. This thesis is focused on the optimization of the extraction process, considered these substances. Maceration was chosen as a type of extraction, due to its simplicity. The Optimal conditions were solid-solvent ratio 1: 5, 40% ethanol, 60 °C, 60 minutes. An extract from the dried flowers of Echinacea purpurea was prepared by this optimized process. The content of total phenolic compounds was set on 365.18 ± 3.51 [mg_GAEl^(-1)] and the antioxidant activity was 507.50 ± 6.89 [mg_TEACl^(-1)]. The percentage of radical scavenging activity ABTS•+ was 95.45 ± 1.30. The antimicrobial activity of the extract was tested against 3 microorganisms – Escherichia coli, Bacillus cereus and Candida glabrata. There was not detected inhibitory effect on the growth of microorganisms. In a total, 39 volatile compounds were identified, and the biggest group were represented sesquiterpenes (70.9%). The obtained results confirm that Echinacea extract has antioxidant activity and contains several interesting aromatic substances, In the future, it can be used as a natural resource of nutritionally and sensory valuable compounds, e.g., into various foods and delicacies.
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Study of volatile compounds of chocolate depending on geographical origin of cocoa beans
Kubínová, Martina ; Kovalčík, Adriána (referee) ; Vítová, Eva (advisor)
Diploma thesis is focused on cocoa beans volatile compounds from various region (Tanzania, Haiti, Ecuador, Madagascar and Peru) and chocolate bars made of them. The main aim was to judge diferences between samples according to geographycal origin. At the same time, samples of chocolates with different content of cocoa solids (50%, 70% „organic“, 70%, 78%, 90%) and a sample of cocoa powder from the common market were analyzed. Volatiles were identified and semiquantified by HS-SPME-GC-MS. A total of 86 volatile substances were identified, they were divided into 7 groups according to the nature of the odor: fruit tones (17), nut and chocolate (16), astringent and sour (12), unspecified (14), sweet nad honey (10), earthy (9) and floral (8). The data were transformed into a 2D graph by analyzing the main component according to selected distinguishing varibles. The difference in the volatile substances of cocoa beans depending on the geographical origin were confirmed using principal component analysis.
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Accuracy of the method for assessment of allergenic aroma compounds
Rychetský, Matěj ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the verification of the accurancy of the method for determination of potentially allergenic substances in confectionery. In the theoretical part the synthetic and natural fragrances, which are present in foodstuffs are described. Furthermore, the method of solid phase microextraction in connection with gas chromatography with mass spectrometry, which was used in the measurement, is briefly characterized. Finally, the basic criteria measured in the validation of the analytical method are described. In the experimental part, the repeatability and reproducibility of the HS-SPME-GC-MS method for the determination of potentially allergenic substances in candy samples was verified. It was found by the measurement that the used method is suitable for qualitative determination (based on retention times), but the method shows minor inaccurancies in quantitative determination (determination based on peaks area) and it will be improved in following experiments.
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Volatile profile of unusual type of fruit (Asimina triloba)
Pallová, Jana ; Šimíčková, Adéla (referee) ; Vítová, Eva (advisor)
The purpose of this bachelor thesis is to determine aroma active substances in an unusual fruit - pawpaw (Asimina triloba). The theoretical part consists of a general description of the plant and characterization of its characteristics, composition and use. Furthermore, the issue of aroma active substances are processed as well as the method of their determination by solid-phase microextraction in connection with gas chromatography and mass spectrometry. The experimental part deals with the identification and quantification of aroma active substances using the selected method HS-SPME-GC-MS in three varieties - PA-Golden, Rebecca's Gold and NC-1. Differences in the number and content of volatile substances were found among the varieties. The lowest values were PA-Golden. In total, 105 compounds have been identified, including 7 aldehydes, 15 alcohols, 58 esters, 6 ketones, 4 lactones, 1 nitrogen compound, 1 alkane, 4 acids, 2 phenols, 1 alkenes, 4 terpenoids, and 2 other compounds.
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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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Obtaining and complex charaterization of Plectranthus spp. extracts
Boboková, Alexandra ; Saláková, Alena (referee) ; Vítová, Eva (advisor)
Plectranthus amboinicus is a herb that was found to have a lot of bioactive compounds, most of them are polyfenolic compounds. Extraction is neccesary to obtain bioactive compounds and to use them subsequently in food or cosmetic industry. Three methods of extraxtion – maceraction, PHWE and PFE, were used in this study. The best yield of extracted polyfenols was observed by maceration. Maceration was, in the next step, optimized using mathematical statistical method of planned experiment (DOE). The optimal conditions found for extraction were: temperature 60 °C, solvent 40% ethanol, time 90 minutes, solid-solvent ratio 1:10. Total phenolic compunds content in this extract was 0,18 ± 0,05 mgGAE·ml-1, which means 1,83 ± 0,53 mgGAE·g-1 of plant. The antioxidant activity was 148,69 ± 26,92 gTEACml-1. Percentage of radical scavenging activity ABTS•+ was 30,03 ± 5,44 %. Further, 27 of volatile aroma compounds were identified in optimal extract, the most important were: -selinene (16,67 %), trans--bergamotene (14,22 %), caryophyllene (14,11 %), 3-carene (8,22 %), -copaene (7,55 %), -terpinene (6,28 %), humulene (5,87 %), cadina-1(10)-4-diene (5,19 %).
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Determination of antimicrobial and antioxidant activity of selected herbal extracts
Čaková, Adriana ; Němcová, Andrea (referee) ; Vítová, Eva (advisor)
Tetradenia spp. is herb naturally growing in Africa and is part of family called Lamiaceae. The herb is used in traditional medicine to cure malaria, angina or as treatment for tropical skin diseases. Maceration was chosen from number of extraction methods, to obtain bioactive compounds from this plant. Optimization was performed with aim to retrieve as much of bioactive compounds as possible. Optimal conditions chosen were: temperature 60 °C, extraction time 40 minutes, solvent 40% ethanol and solid-solvent ratio 1:5. In total 63 aromatic active compounds were found in optimal extract. Terpenes were the most abundant (88,60 %), from them oxygenated monoterpenes (55,65 %) and monoterpenes (29,52 %). Compounds with highest percentage quantity were camphor (51,76 %), cis--ocimene (8,17 %), 3-octyl acetate (7,71 %), trans--ocimene (6,76 %), -terpinene (4,93 %), o-cymene (3,81 %), terpinolene (1,33 %), limonene (1,33 %), camphene (1,19 %) and borneol (1,20 %). Further, total phenolic content was 0,31 ± 0,02 mgGAEml-1, which equals 1,52 ± 0,11 mgGAEg-1 of plant. Antioxidant activity was 417,56 ± 32,84 gTEACml-1 and percentage of radical scavenging activity ABTS•+ was 88,99 ± 7,00 %. Finally antimicrobial activity was determined against bacteria Bacillus cereus, Escherichia coli and yeast Candida glabrata. Against E. coli and C. glabrata there was no inhibition exhibited. Against B. cereus there was seen mild inhibition activity. The results confirm that Tetradenia spp. contain a number of interesting aroma active compounds, which shows antioxidant and antimicrobial activity. The herb has a good potential as natural source of nutritious and sensory active compounds to be used into various foods.
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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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Beer bioflavouring by dry hopping using czech cultivars of hops
Gajdušek, Martin ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with the influence of dry hopping on selected analytical and sensory properties of beer. The effect of dry hopping was observed using Czech hop varieties Kazbek and Uran, which were added to the wort during the main fermentation phase in doses of 3 and 6 gdm-3. The contact time of hops with wort was 3, 6 and 9 days. The experimental part describes the technology of preparation of the reference beer, in which dry hopping were subsequently performed. A parallel measurement was performed on each sample. In terms of the basic parameters of beer, the effect of dry hopping, especially its length, on the ethanol content was observed. With a longer period of dry hopping, the concentration of ethanol in beer increased. The higher alcohol concentration was also associated with a decrease in the apparent extract. In terms of color and pH of beer, the effect of dry hopping has not been proven. Elemental analysis performed by optical emission spectrometry with inductively coupled plasma revealed an increase in the concentration of calcium, magnesium, and iron due to dry hopping. No statistically significant difference was observed for manganese and barium compared to the reference. In terms of bitterness, a significant increase was identified in dry hopped beers compared to the reference, the value being dependent on the dose of hops used. The effect of the hop variety has not been proved. Concentrations of organic acids determined by ion-exchange chromatography with a conductivity detector were affected by dry hopping only in the case of lactic acid and acetic acid. An increase in lactic acid was observed compared to the reference, also related to the degree of fermentation. While in the acetic acid content the hop samples showed a lower concentration than the reference sample. The concentrations of myrcene, humulene and geraniol were determined by gas chromatography with a mass detector. These are volatile components of hop essential oils. Dry hopped samples recorded significantly higher concentrations of all aromatic substances compared to the reference. In terms of hop time, the highest concentrations were shown by samples hopped for three days. The results of the sensory analysis show that the overall best rated sample is a sample hopped with the Kazbek variety with a dose of 3 gdm-3 for three days. Beer which was dry hopped for the shortest time also showed the lowest intensity of bitterness, which was perceived positively.
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Production and characterization of fresh cheese analogues with the addition of nut oils
Lovásová, Kristína ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
Diploma thesis deals with the production and characterization of fresh cheese analogues with added nut oils (walnut, hazelnut, and almond oil). The purpose of the thesis was to prepare cheese samples with an improved nutritional value and better sensory quality. The experimental part deals with the characterization of the prepared samples in terms of fatty acids, volatile substances, content of fat in dry matter, antioxidant activity and sensory quality. Fatty acids were determined using the gas chromatography with a flame-ionization detector after the conversion to methyl esters by the acid esterification with boron trifluoride. The determination of the volatile compounds was performed through the solid-phase microextraction with the gas chromatography separation and the mass spectrometry detection. After the extraction and drying the samples, the dry matter and fat content in the dry matter was determined. Antioxidant activity was determined by the Trolox equivalent antioxidant capacity method and the sensory quality was assessed by the evaluators. In the comparison of fat in the dry matter there was a difference between the standard sample and the analogues. The samples with the added oil were higher in fat content that the standard sample without oil. All samples can be classified into the category of half-fat cheese. A total of 17 fatty acids were identified. The total content of fatty acids did not differ significantly. With the addition of nut oils, the amount of saturated fatty acids decreased and the amount of mono- and polyunsaturated fatty acids increased. A total of 40 volatile (aroma) compounds were identified in all samples. 22 compounds were identified in the standard sample; 25 compounds in the sample with walnut oil; 26 with hazelnut oil and 27 with almond oil. Alcohols, acids, and ketones were present in the largest amounts. The measured antioxidant activity of the analogues was higher that the activity of the standard sample. The highest activity was measured in the sample with walnut oil. From the sensory perspective the sample with hazelnut oil was evaluated as the best. The sample with walnut oil was evaluated as the worst. Added oils influenced the taste and the odour of the analogues but they also had an impact on the texture and the hardness of the samples. The obtained results indicate that the addition of nut oils influences the properties of cheese. It increases the nutritional value (lower amount of saturated fatty acids and higher amount of unsaturated fatty acids, higher antioxidant activity) and, except for the sample with walnut oil, even the sensory quality and the acceptability were evaluated as better.
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