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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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Characteristics of the different varieties of the Asimina triloba fruit
Maradová, Terezie ; Křikala, Jakub (referee) ; Diviš, Pavel (advisor)
This thesis describes pawpaw, fruit from east states of USA. Main part of this work is focused on nutritional characteristic of three species and their comparation. The analyzed species are PA Golden, NC-1 and Rebecca’s gold. Characteristic contains determination of lipids isolated by Soxhlet extraction, determination of proteins by Kjeldahl method, elemental analysis using ICP-OES, determination of saccharides and vitamin C by HPLC, determination of organic acids using IC and spectrofotometric analysis of phenolic compounds. This study shows, that pawpaw is interesting fruit, rich in nutritionally important compounds. That‘s why the cultivation and research of this fruit in South Moravia should continue in the future.
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Study of geographical authenticity of moravian red wine
Bidmonová, Karolína ; Punčochářová, Lenka (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis discusses the possibility of using analytical methods to determine the elemental profile of wine and to detect phenolic substances in wine. The theoretical part describes the Czech and Moravian subregions, chemical composition of wine, authenticity and methods of assessing the authenticity of wine. The next part contains a brief description of the analytical methods that were used in the experimental part. The experimental part deals with the determination of the elemental profile of wine by mass and optical emission spectrometry, the determination of phenolic substances by high performance liquid chromatography, the determination of antioxidant activity and the total content of phenolic substances. For the purpose of classifying wine samples into groups, multidimensional statistical methods (cluster analysis, principal component analysis, analysis of variance and discriminant analysis) were used to separate the groups according to geographical origin.
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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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Concentration of selected metals in traditional and herbal teas
Brlíková, Eliška ; Křikala, Jakub (referee) ; Diviš, Pavel (advisor)
This thesis deals with determination of selected metals concentrations in loose green, black and herbal teas purchased in the Czech Republic and beyond. All samples were analyzed by ICP-OES. Most metals were not detected in the extracts. The final metal concentrations that have been detected in the tea extracts meet the legislative limits and do not bring a health risk to humans. The statistical processing of the measured results, based on different concentrations of selected elements, managed to distinguish the extracts from black and green teas.
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The study of zinc influence on Portland cement hydration.
Ptáček, Martin ; Janča, Martin (referee) ; Šiler, Pavel (advisor)
The topic of this work is the monitoring of the effect of zinc on the hydration process in Portland mixed cement (specifically with the addition of finely ground granulated blast-furnace slag, high temperature fly ash and fluidized bed combustion filter ash). How much zinc and at what time it remains in the pore solution during hydration. Activation energy of a mixture of cement with zinc in the form of soluble salts (Zn(NO3)2.6H2O and ZnCl2) and insoluble oxide (ZnO) by isothermal calorimetry was also investigated. The XRF method has shown composition during hydration. The zinc retardation effect was investigated by isothermal calorimetry and activation energy was calculated using this method. The XRF and ICP-OES methods were used to measure the zinc content of the pore solution. And the amount of portlandite was monitored by the DTA and XRF method.
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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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Development of method for determination of qualitative parameters of cocoa powder
Vránová, Petra ; Vítová, Eva (referee) ; Vespalcová, Milena (advisor)
The theoretical part of the master’s thesis is focused on a brief botanical characterization of the cacao tree and its most famous varieties discussed. Furthermore, the chemical composition of cocoa beans is described with an emphasis on theobromine and caffeine. There is also mention of the cocoa beans the cocoa bean processing technology for cocoa liquor and cocoa powder, which are then used in food industry. Additionally there is a shorta short description of the legal requirements relating to cocoa. In this part are also two chapters are devoted to the description of instrumentation of high performance liquid chromatography (HPLC) and inductively coupled plasma optical emission spectrometry (ICP-OES). The experimental part deals with analyzes of cocoa powder, cocoa beans, cocoa liquor and waste cocoa beans sold as a "tea mixture". A total of 10 legislation-recommended parameters have been identified in the listed raw materials, such as caffeine, theobromine and sucrose, heavy metal and potassium, fat content etc. The highest content of theobromine was determined in cocoa powder 178.363 mgl-1, caffeine in cocoa beans 16.096 mgl-1. All samples analyzed contained a little amount of sucrose as expected, the highest concentration was found in the tea mixture samples in both the water: ethanol sample of 84.069 mgl-1, and the sample solution in water of 65.897 mgl-1.
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Impact of post-harvest processing, geographical locality and production year on quality of selected medicinal plants
Burdějová, Lenka ; Polovka, M. ; Pořízka, J.
This study deals with the assessment of the impact of post-harvest treatment, geographical location and production years on 32 selected characteristics of medicinal plants grown in the Czech Republic. Dimethyl sulfoxide herbal extracts characteristics were evaluated by spectroscopic and chromatographic techniques. The results were processed by analysis of variance and multivariate statistical tools. Obtained results clearly proved the successful differentiation of herbal samples by means of canonical discrimination analysis according to post-harvest treatment (100%), geographical origin (82.9%) and production year (96.1%) confirming that studied factors may have significant effect on quality of medicinal plants.
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