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Validation of HPLC method for determination of organic acids in beverages
Hanychová, Silvie ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
This diploma thesis focuses on validation of RP–HPLC method for determination of organic acids in fruit juices. The aim of this thesis was to determine suitability of the method for verification of the fruit juices authenticity based on analysis of organic acids. The theoretical part describes chemical composition of fruit and fruit juices and focuses on organic acids. It provides description of various methods of organic acids analysis with more detailed description of High Performance Liquid Chromatography and its validation. The experimental part focuses on optimalization and validation of the method. Samples of malic, citric, succinic and ascorbic acid were analysed. The optimalized method was validated and following performance parameters were determined: repeatability, linearity, limit of detection (LOD) limit of quantitation (LOQ). RP–HPLC method was applied to real samples of 100% fruit juices (apple, orange and grapefruit) and the authenticity parameters were verified.
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Determination of organic acids in beer
Štáblová, Taťána ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
The topic of this bachelor’s thesis is determination of organic acids in Czech beers with protected geographical indication. There are described the main components for beer production and the production of malt and beer itself in the theoretical part. Part of this work is dedicated to analytical methods used in determination of organic acids. High–performance liquid chromatography and ion chromatography were used to determine the content of organic acids. The experimental part deals with sample preparation, calibration solutions and procedure of analysis. The obtained results of analyzed substances are summarized, discussed, and compared with results of analyses of foreign papers. Differences in content of organic acids in lager and draught beers were determined. Five lager beers and five draught beers were used for the analysis.
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Production and characterization of mead produced by different technologies
Kilian, David ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis is focused on the technology of producing mead from the chosen kind of honey with a variety of sugar concentrations with the use of modern producing technological procedures with the cold and hot process. The theoretical part is focused on the history of mead and its technological development. It focuses, in detail, on modern large scale technologies – both cold and also the hot process. In the practical part of the thesis, the production of samples of mead with various sugar concentrations from three kinds of honey with the use of two technological processes (hot and cold process) was conducted firstly. Secondly, the characteristics of the samples were conducted from the view of the volume of HMF – Hydroxymethylfurfural, ethanol, glucose, fructose, the chosen organic acids and elements with sensory analysis. The prepared samples were compared and discussed concerning differences to find out the differences of the use of the two manufacturing technologies (cold and hot process), the chosen kinds of honey and the influence of sugar before the fermentation on the final product.
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Screening of biotechnological potential of selected members of the genus Geobacillus and other related genuses
Kouřilová, Xenie ; Brázda, Václav (referee) ; Obruča, Stanislav (advisor)
This diploma thesis deals with selected thermophilic representatives of genera Geobacillus, Saccharococcus and Bacillus, taking screening of its biotechnological potential into account. Bacteria from the first two genera came from Czech and German collection of microorganisms, while bacteria of genus Bacillus were natural isolates. Researched strains were examined from a viewpoint of carbon source utilization and furthermore, production of biosurfactants, extracellular hydrolytic enzymes (protease, amylase, lipase, cellulase, xylanase), organic acids, antimicrobial agents and microbial plastics – polyhydroxyalkanoates was also tested. Bacteria S. thermophilus, G. uzenensis and G. zalihae evinced a substantial ability of biosurfactant production. Strains G. jurassicus, G. uzenensis, G. gargensis and G. lituanicus were capable of intensive production of all tested, technologically significant enzymes. Highest antimicrobial effects were reached with bacteria G. stearothermophilus and G. thermocatenulatus. Largest production of acetic acid was achieved with G. jurassicus and lactic acid with G. thermodenitrificans. Ability to produce polyhydroxyalkanoates was proved at genotype level by some cultures only, however at fenotype level, response was negative. On the contrary, bacteria genus Bacillus were able to produce polyhydroxyalkanoates, although in small amounts under given circumstances. With remaining researched metabolites, production ability was considerably lower, compared to genera Geobacillus and Saccharococcus.
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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.
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Determination of macroelements, organic acids and other parameters in ketchups
Popelová, Nikola ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
The aim of this master’s thesis is perform basic analyses of samples ketchups. The theoretical part describes the basic characteristics of tomato, tomatoes processing and production of puree and ketchup. Then there are described analytical methods which were used for analysing the selected parameters in ketchups. The experimental part deals with the determination of pH, total solids, organic acids, saccharides, macroelements and lycopene in ketchups. Citrate and acetate were analysed by IC. The amount of acetate in ketchups was about 5 times greater than the amount of citrate. Glucose, fructose and sucrose were analysed by HPLC. Glucose and fructose were determined in all samples but sucrose not. The ICP-OES method was used to determine four elements. Magnesium was the least represented element and sodium was the most represented element in the analysis. The amount of sodium was recalculated on the amount of salt. Lycopene was analysed by UV-VIS spectrometry. Its amount in ketchups is influenced by the variety of used tomatoes and plenty of other factors.
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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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Portable and Miniaturized Separation Techniques Applicable for Food and Biotechnology Analysis
Dvořák, Miloš ; Pospíchal, Jan (referee) ; Bednář,, Petr (referee) ; Rittich, Bohuslav (advisor)
Capillary electrophoresis was used for determination of 6 fractions of caseins. Those fractions were measured in 144 samples of cow’s milk originated from the feeding experiment focused on explanation the influence of the feeding onto casein productions. In this work were separated 6 fraction of caseins first time with total resolution of the peaks. Capillary electrophoresis was applied for determination of short-chain organic acids during fermentation of wine must. It was compared the fermentation of must fermented by different yeast. The difference of profile short-chain organic acids during fermentation were not statistically significant. The once difference was in the utilisation of the malic acid and production of the lactic acid. A portable miniaturized system for medium pressure liquid chromatography was developed. The components were tested and system was used for the isocratic and gradient elution of various analytes (food dyes, parabens). New line of electroluminescent diodes (LEDs) for deep-UV areas of wavelength based on a different materials substrate was characterised. The new line was compared with old line LEDs. The new line LEDs was incorporated in deep-UV absorbance detectors. Detectors were characterised and tested for a detection various analytes in modes flow injection analysis and chromatography separation. First time was characterised this new line of the LEDs and the origin of the parasitic emission band produced by deep-UV LEDs light sources was explained. This origin is given by disturbances of a materials substrates. This work is a contribution for an advance of low-cost and portable systems and detection devices in the field of analytical chemistry.
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Chemical composition of wine produced from PIWI cultivars
Michálková, Kateřina ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deasl with the chemical charakterization of wine from selected PIWI varieties. The theoretical part describes the general origin and reason for breeding PIWI varieties, a closer characterization of selected three PIWI varieties, Johaniter, Hibernal and Solaris. The next part is devoted to the description of analytical methods that were used to determine the chemical characteristics. The experimental part is developed to the determination of chemical characteristics, namely general characteristics such as alcohol, total phenols, phenolic substances, volatile substances and elemental composition. The results show that are differences between wines from selected PIWI varieties in therms of chemical composition. The most represented organic acid was in the range of 735,1-1286,2mg/l malic acid. This was followed by acetic in the range of 100-400mg/l. The antioxidant activity was determined in the range of 0,2988-0,9683 mmol/l of Trollox and content of total phenols 273,5-390,3mg/l. Of the phenolic substances, gallic acid was the most represented, ranging from 6,9-13,9mg/l. As another, abundant phenolic substances, catechin in the range of 1,6-6,0mg/l was detected. Of the determined elements, phosphorus in the range of 165,4-450,5mg/l was the most represented. Representatives of ethyl ester, ethyl acetate, decanoic acid ethyl acetate and hexanoic acid ethyl ester, were detected as the most abundant volatiles. From the measured data it was evident that wines from PIWI varieties different from standard varieties, especially in the profile of aromatic substances.
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Determination of selected parameters in special types of beers brewed in the Czech Republic
Fähnrichová, Nikola ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with analysis of special types of beer brewed in the Czech Republic using three instrumental methods. Polyphenols were determined by high performance liquid chromatography. To determine organic acids was used ion exchange chromatography. Elementary analysis was performed by inductively coupled plasma optical emission spectrometry. The theoretical part of the work describes technology of beer production, chemical composition of beer, especially groups of substances which were analysed in this thesis. Principle of used methods is also described. The practical part of the work deals with preparation of tested samples, calibration samples and process analysis. The obtained results of analysed substances are summarized in the tables, discussed and compared with results of analysis of other authors. For the analysis it was used eighteen different types of special beer produced in the Czech Republic.
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