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Influence of coffee making process on chemical composition of brewed coffee
Trenzová, Kristina ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with the influence of baristic coffee preparations on the chemical composition of the obtained beverage. Teoretical part of this thesis focuses on coffee growing, processing technology and the chemical composition of coffee beans. In the experimental part were measured samples of espresso coffee, samples prepared by moca pot, flip-drip method, filtrated coffee, samples prepared by french-press technique, vacuum pot samples and boiled coffee. The samples were prepared according to the baristic techniques at first and later with adjusted water and amount of coffee so these methods could be compared with each other. This work focuses on the determination of caffeine and acrylamide content by liquid chromatography, validation of HPLC method, determination of total phenolic content by Folin-Ciocalteu reagent, determination of organic acids by ion chromatography, determination of selected macro and micro elements by inductively coupled plasma in optical emission spectrometry and analysis of aromatic substances using gas chromatography. Based on the processed results and compared methods, it was shown that the moca pot had the greatest influence on the content of caffeine, acrylamide, organic acids and total phenolic substances, and the flip-drip with vacuum pot method had the greatest influence on the content of aromatic substances. From a baristic point of view the highest concentration of caffeine was 3689 mg/l in coffee based on flip-drip method, and concentration of acrylamide was 25,4 mg/l in the coffee based on the same method. The highest value of total phenolic content was determined in moka pot to c = 5,23 g/l. Regarding the mineral representation, the mineral decomposition of coffee beans and espresso were compared, and the highest values were reached by potassium, namely the concentration was 577 mg/l per 1 g of mineralized sample, in the cup of espresso the potassium concentration was 2461 mg/l. The highest content of organic acids was determined in the beverage prepared by moca pot, in terms of selected acids, the largest representation had the succinic acid with the concentration 599,8 mg/l. The highest content of aromatic substances was found in coffee from a moca pot and in coffee by flip-drip method. The biggest part was~made by furfuryl alcohol.
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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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Chemical and sensory characterization of cider made from apple cultivars ordinarily grown in Czech republic
Strapcová, Zuzana ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This master thesis deals with the investigation of selected chemical and sensory characteristics of ciders, which were made from four selected apple varieties. The theoretical part describes the chemical composition of apples, cider, the technology of production and production in the world. The next section describes the analytical methods used to determine chemical characteristics not only in ciders but also in other alcoholic beverages. The experimental part focuses on the determination of chemical characteristics such as the content of organic acids, carbohydrates, total phenolic content, alcohol antioxidant activity and elemental composition. The purpose of the work was to find out how different varieties differ in chemical composition. The produced ciders were subjected to sensory analysis to evaluate the selected cider sensory parameters, which were in the natural state and with the addition of carbon dioxide. The results show that ciders of different varieties differ in chemical composition. Malic acid was the most cider's abundant of the organic acids in the range of 2759 – 4411 mg·l-1. Another acid represented was lactic acid in the range of 166,2 – 288,1 mg·l-1. The glucose content of each cider was determined between 845,3 – 1159,8 mg·l-1and fructose 32,6 – 406,7 mg·l-1. Potassium 944,29 – 1073,98 mg·l-1 was the most represented of all elements. The total phenolic content was determined to be in the range of 164,2 – 214,1 mg of GAE·l-1and the antioxidant activity of 0,192 – 0,318 mg·l-1. These differences in chemical composition were also reflected in sensory evaluation. According to the overall assessment, the best cider was made from the Granny Smith variety, which contained the most organic acids and carbohydrates. It has been found that by adding carbon dioxide, sensory parameters such as colour, taste and smell are altered.
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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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Electrophoretical determination of corrosion inhibitors in engine coolants
Smrž, Dominik ; Kubíčková, Anna (advisor) ; Coufal, Pavel (referee)
A determination of corrosion inhibitors in engine coolants represent a difficult analytical problem due to their different physicochemical properties. Nowadays a lot of instrument methods are needed to determine them. The aim of this work was the development of methods for their determination using only one instrumentation. Capillary zone electrophoreses was chosen as a suitable technique. Three electrophoretic methods for three groups of corrosion inhibitors were developed. Firstly, method for determination of inorganic anions was developed in range from 5 to 50 ppm with limit of detection around 1 ppm. Background electrolyte contains sodium chromate, CTAB and CHES solution. Analytes were detected indirectly at 450 nm. Another method was for determination of organic acids anions. They were determined in range from 5 to 500 ppm. Limit of detection for each analyte was around 1 ppm. Measurement was made with PDC a CTAC water solution. Indirect detection was used for this determination at 350 nm. Last developed method can be use for determination of aryltrizoles in range from 5 to 500 ppm. Limit of detection was around 1 ppm. As a background electrolyte was used sodium tetraborate solution. The developed methods were validated and their suitability for determination of corrosion inhibitors in real...
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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 of organic acids by fibrous microscopic fungi and utilization of their biomass for removal of risk elements
Juglová, Zuzana ; Hudečková, Helena (referee) ; Urík,, Martin (advisor)
The aim of this bachelor thesis was to determine the most advantageous method for production of organic acids by microscopic flamentous fungus Aspergillus niger and to evaluate mercury bioaccumulation efficiency on collected fungal biomass. The theoretical part focuses primarily on utilization, metabolism and production on individual organic acids. This is followed by section focused on the toxicity of mercury and the principles of bioaccumulation of heavy metals in biomass. The experimental part focuses mainly on the optimization of cultivation, determination of content of produced organic acids, depending on the type of cultivation. Second point of practicle part is evaluating of mercury bioaccumulation depending on the initial concentration of mercury in solution. In overall comparison, the best type of cultivation is dynamic. Higher biomass yeild resulted in higher production of organic acids. The higher biomass synthesis is also beneficial for bioaccumulation of mercury.
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Determination of organic acids in wine
Michálková, Kateřina ; Mravcová, Ludmila (referee) ; Řezáčová, Veronika (advisor)
This bachelor thesis deals with determination of organic acids in wine by capillary zone isotachophoresis method. The theoretical part is devoted to the properties of wine, its composition, its benefit to human health and capillary zone isotachophoresis and its practical use. The practical part deals with determination of organic acids in wine by capillary zone isotachophoresis. Organic acids are determined in three phases of white and red wine production.
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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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The intake of food organic acids and the influence on hard dental tissues
Procházková, Nikola ; Krugová, Alena (advisor) ; Zavřel, Viktor (referee)
This bachelor thesis deals with the influence of organic acids on hard dental tissue. The theoretical part is focused on the construction of tooth-enamel, dentin and cement and, of course, to individual organic acids. Furthermore, the disease-dental erosion caused by acids is theoretically described. The practical part consists of evaluated questionnaires. Questions in the questionnaire are formulated to respond to the goals I have set out. The questionnaire was in two forms. The first form was electrocnic and was placed on the Internet. 65 respondents answered this questionnaire. The second form was printed and was placed in the waiting room of the dental clinic in Černý most. The total number of respondents was 102. After evaluating the questionnaire survey, I identified the risk of erosion. The questionnaire survey should also reveal the subjective feeling of patients after ingestion of organic acids.
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