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Analysis of selected elements in milk by ICP-OES
Sekaninová, Renáta ; Vespalcová, Milena (referee) ; Diviš, Pavel (advisor)
This Master's thesis is dealing with elementary analysis of milk. Theoretical part describes general characteristics, terminology with basic legislature and classification of milk. Large part is focused on chemical composition, especially on description of mineral substances selected for analysis in experimental part of this thesis. Choices of elementary analysis and preparation of samples for ICP-OES method conducted by other authors are also mentioned. Specification of emission spectrometry with inductively coupled plasma is crucial, a technique used for purposes of this dissertation. Experimental part deals with preparation of samples, approach of analysis and processing of measured results. The aim of this part is to compare concentration of analyzed elements in different kinds of milk. Samples from 15 different kinds of milk were used for analysis, which were determined by ICP-OES method. Results were compared to each other in discussion as well as with results from other authors.
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Basic chemical characteristics of juices of selected white gooseberry varieties
Zelníčková, Jaroslava ; Diviš, Pavel (referee) ; Vespalcová, Milena (advisor)
Theoretical part of this bachelor thesis includes taxonomical classification of gooseberry, deals with biological characteristics, active substances contained in fruits of gooseberry and its using as well with description of the methods by research detection. In the experimental part primary nutritional parameters of chosen gooseberry species were analysed including orientation juice yield, soluble solids, pH, dry matter, titratable acids, formol number and reducing sugars. There were analysed following species of gooseberry: Reflamba, Mucurines, Rixanta, Veliš, Citronový obří, Darek, Prima, Invicta, Zlatý fík a Zebín. Individual species and cultivars were compared based on the results.
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Characterization of the resin gels for mercury determination by DGT technique.
Finsterlová, Hana ; Řezáčová, Veronika (referee) ; Diviš, Pavel (advisor)
The aim of this thesis is testing of resin gels used in diffusive gradients in thin films technique (DGT) for determination of mercury in natural waters. The sorbets, chosen for preparation of resing gels were: Duolit GT- 73, Spheron- Thiol, and Chelex 100 and newly modified sorbent Iontosorb AV. At the beginning of work, the preparation procedure of all resing gels was optimized. After optimalization of preparation procedure the resin gels were tested in mercury model solutions. The recovery test and time dependence test were performed. When the basic tests were finished, they were followed by the tests of influence of natural ligand (humic acids and chlorides), and other parameters (above all pH and ionic strenght), on mercury determination by DGT technique.
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Determination of selected parameters in foreign beers
Punčochářová, Lenka ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
The aim of this thesis is determination of selected polyphenols, organic acids and elements (major and minor) in a foreign beers. Production of malt, beer production, beer types and beer styles are described in the theoretical part. Also analytical methods of beer analysis such as high performance liquid chromatography, iont chromatography and inductively coupled plasma optical emission spectrometry are described. The Experimental part deals with preparation of samples and calibration solutions, setting devices up and analysis of foreign beers samples. There were analyzed 14 foreign beers of which 11 samples were top-fermented beers, 3 samples were bottom-fermented. Four samples were produced in Belgium, three in England, three in Germany, two in the US, one in Holland and one in Poland. The results give an overview of the contents of compounds in foreign beers.
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The optimization and validation of the method for assessment of free fatty acids
Sýkora, Michal ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This master thesis deals with the development of method for free fatty acids determination in natural and processed cheese. In the theoretical part the possibilities of extraction, fractionation and determination of lipid fractions, characterization of fatty acids and various methods of their determination are described, as well as determination of free fatty acids. The main scope of the experimental section is optimization and validation of the selected method for determination of free fatty acids in various cheese matrices. For extraction of lipids from the sample the method with the mixture of diethylether and petrolether according to ČSN EN ISO 1735 was selected. Thin-layer chromatography and solid phase extraction were tested and compared for separation of free fatty acids. The method according to ČSN EN ISO 5509, using methanol solution of bortrifluoride, was applied for esterification. Fatty acid methyl esters were determined by gas chromatography with flame-ionization detection.
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Draft beer analysis by HPLC-ELSD and IC
Vanduchová, Petra ; Vespalcová, Milena (referee) ; Diviš, Pavel (advisor)
In this bachelor thesis is discussed the brewing process and composition of the beer. The experimental part deals with analysis of polyphenolic compounds and carbohydrates by HPLC, analysis of organic acids by the IC and the ICP-OES method was used for analysis of elements. The HPLC method was used to determine eleven polyphenols. Gallic acid was the most represented compound of polyphenols and quercetin was the least represented compound. Glucose, fructose and sucrose were analysed by HPLC and the most represented compound of carbohydrates was glucose. The ICP-OES method was used to determine ten elements. Zinc was the least represented element in the analysis and phosphorus and potassium were the most represented in the analysis.
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Monitoring the stability of the beer brewing process
Tichá, Anna ; Štursa, Václav (referee) ; Diviš, Pavel (advisor)
The bachelor thesis deals with the analysis of 3 samples of the same beer, brewed in different batches of the brewing process. The analyzed sample is Dalešická jedenáctka - light lager of 11% of the Stock Brewery Dalešice, a.s., which was taken directly from the lager tanks in the brewery. The aspect we have examined were total protein content, total carbohydrate content, maltose content, total polyphenol content and ethanol content. The Hartree-lowry method was used to analyzed the total protein content. Total carbohydrates were measured spectrophotometrically using anthrone reagent. The maltose content was analysed by HPLC with an ELSD detector. The total polyphenol content was analyzed by the Folin-Ciocaltau reagent method and measured spectrophotometrically. The ethanol content was analyzed on a HPLC using a refractometric detector. The aim of the work was to compare to what extent the process of beer production is stable and what parameters may change in the final product
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Study of changes in the chemical composition of coffee during roasting
Kohoutová, Lenka ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with monitoring of changes in acrylamide and hydroxymethylfurfural levels in coffee during the process of roasting. Green coffee was roasted using two separate roasting modes (medium roast: temperature 210 °C for duration of 14 minutes, City roast: temperature 220 °C for 17 minutes). Concentration of acrylamide and hydroxymethylfurfural for various roasting durations was determined by high performance liquid chromatography. For the determination of acrylamide, linear growth of the concentration was observed. The final levels of acrylamide corresponded with levels given by the literature, although the characteristic trend of acrylamide formation was not observed. Typical trend of hydroxymethylfurfural formation was observed in samples roasted with City roast mode, while the first part of the trend was also apparent in samples roasted with medium roast mode. Final levels of hydroxymethylfurfural in roasted coffee were within the limits given by the literature.
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Determination of selected metals in grapes cultivated by different techniques
Kubicová, Lenka ; Vespalcová, Milena (referee) ; Diviš, Pavel (advisor)
The aim of this study is to determine the content of selected metals (As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Se, Sn, Sr, Pb, V, Zn) in samples of leaves and grapes produced by ecologic agriculture and compare to results with leaves and grapes produced by integrated agriculture. The measured results used to assess the impact of agricultural technology on the quality of vines and grapes. The amount of elements was analysed using inductively coupled plasma mass spectrometry after previous digestion of sapmles using microwaves. Concentrations of elements in leaves and grapes from organic and integrated farming did not differ significantly only in the case of copper concentrations were measured higher concentrations in samples from organic farming. This difference is probably caused by different doses of authorized protective equipment based on copper in the organic and integrated farming.
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Monitoring of chemical composition changes in wine during the wine making process
Orságová, Marie ; Punčochářová, Lenka (referee) ; Diviš, Pavel (advisor)
The Chardonnay wine variety was harvested in the region of Znojmo on the wine rout Načeratický kopec. In connection with the entire winemaking process of this particular variety, research was focused on mineral concentration changes during the maturation process. The theoretical part characterizes the technology of wine production, as well as the classification and chemical composition of wine. In the experimental part, the analytical technique of inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the determination of minerals (K, Ca, P, Mg, Na, Zn, Cu, Fe and Mn) in wine. The data show the differences in the concentrations of all macroelements and microelements during the whole wine production technology.
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