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Determination of semimetals in selected food samples
Gállová, Eva ; Vitoulová, Eva (referee) ; Diviš, Pavel (advisor)
This diploma thesis deals with an optimization technique for the determination of semimetals in selected samples of food, which consists of sample digestion, preconcentration and detection of the elements. Preconcentration is usually chosen because these elements are contained in foods only in trace amounts, which are undetectable for some techniques. This work also made characteristics of semimetals, in terms of their functions in the body, of the occurrence in food and the consequences for the organism on their surplus or shortage. The chosen technique of preconcentration in this work was the preconcentration of titanium dioxide. When optimizing the techniques, however, was unlike the results published in literature, obtained low yield of elements sorbed on titanium dioxide, therefore the samples were measured by inductively coupled plasma mass spectrometry directly after their mineralization, wet digestion with low temperature. The results of this work indicate that the elements arsenic, boron and selenium are given technique detectable without preconcentration, whilst set germanium content in all samples failed, due to very low concentrations and therefore in these cases would be required preconcentration.
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Elemental analysis of different kinds of small fruit
Štursa, Václav ; Vespalcová, Milena (referee) ; Diviš, Pavel (advisor)
This diploma thesis deals with the elemental analysis of soft fruit species such as currants and gooseberries. The theoretical part contains botanical description of both species, then description of nutritional properties of the individual analyzed elements and ends with a list of analytical methods suitable for elemental analysis in the food science and with a description of preparation. The experimental part deals with sample preparation and its analysis afterwards with spectroscopic techniques. Samples of different varieties of gooseberries, black, red and white currant from “Výzkumný a šlechtitelský ústav ovocnářský v Holovousích, s.r.o.” have been used for the analysis. Samples were mineralized in concentrated HNO3 and analyzed by ICP-OES technique. Difference in resultant concentrations of the analyzed elements (Ca, Cu, Fe, K, Mg, Mn, Na, P, Zn) between individual varieties were statistically compared by Tukey’s multiple comparison method and results achieved have been as well compared with the results reported in available literature.
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The study of various methods of preparation of the milk sample for milk analysis by ICP-OES technique
Kaňová, Veronika ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
The theoretical part of the thesis deals with the chemical composition of cow’s milk, with the description of chosen methods of sample pretreatment and with the description of the used technique ICP-OES. The practical part is aimed at individual preparations of samples and at analysis of chosen chemical elements (Ca, Na, K and Mg). Milk is a really complicated polydisperse system, that’s the reason why the preparation of samples with milk is very important step before the measurement itself. In addition to accuracy choosing the sample adjustment method, other factors such as time, work intensity, or cost need to be considered when. In the thesis a comparison of four selected methods of sample preparation was made: direct analyse of milk, dilution with addition of Triton X-100, wet microwave ashing and destruction of matrix with TMAH (tetramethylammonium hydroxide). Selected elements were analysed with the help of ICP-OES. This diploma thesis builds on the bachelor thesis, which deals with the same problem. Final concentrations were compared with certified values of skimmed powdered milk. Data showed that the most accurate are methods of preparation of wet microwave ashing and destruction of matrix with TMAH. By using these methods, the effect of the dairy matrix that caused problems in the analysis, was largely eliminated. The diluted samples with and without Triton X-100 showed a bigger anomaly of measuring than the mineralization of wet ashing which came to the loss of analyte because of fat elements contained in milk.
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Determination of micro and macro elements in bottled water by ICP-OES technique
Herman, Vít ; Vespalcová, Milena (referee) ; Diviš, Pavel (advisor)
This Master’s thesis deals with the determination of selected micro and macro elements in bottled water purchased in retail chains Czech Republic. There are described macro elements and micro elements that occur in the waters, bottled waters legislation and the most frequent used instrumental methods for elemental analysis. In this work for the analysis of bottled water were used methods optical emission spectrometry with inductively coupled plasma (ICP-OES) and ion chromatography (IC). Elemental composition of bottled water after analysis corresponded to the composition indicated on the labels, there were recorded only minor deviations from the reported concentrations. All bottled water meets the conditions of the legislation of the Czech Republic. The measured data were statistically processed in the XL Stat program and by multivariate data analysis was examined whether it is possible to individual bottled water from each other based on the analyzes differentiate, which can help in verifying the authenticity of bottled water and in the detection of adulteration of bottled water for profit.
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Monitoring of the tin release to the canned fruit from the used packaging
Flajs, Roman ; Vránová, Dana (referee) ; Diviš, Pavel (advisor)
This master’s thesis deals with the issue of the release of tin in canned fruit of used packaging. The theoretical part of the thesis is described canning fruit as raw material, its composition, methods of preservation, basic technological operations fruit processing, manufacture of compote, manufacture of metal packaging, marches corrosive metal packaging, chemical behavior of tin in foods and toxicity, methods for the determination of tin in foods with a focus on optical emission spectrometry with inductively coupled plasma. I the experimental part of the thesis was first ICP-OES optimized before to analysis of the 20 different samples compote purchased in chain stores. Tin concentration was determined by a fixed proportion compote. Measured concentration of tin were compared with the maximum permissible value in canned foods, which is allowed by European legislation. The tin content in all analyzed compote did not exceed the legislative limit of 200 mg/kg. The highest concentration of tin has been measured in sample conserved apricots namely 88,6 ± 2,8 mg/kg.
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Characterization of the genus Plectrantus for use in the food industry
Chmelová, Nikola ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis was to determine the optimal extraction conditions for obtaining an extract from the plant Plectranthus amboinicus. Plectranthus amboinicus is an aromatic herb of the Lamiaceae family containing a large number of bioactive compounds. Because of this, it has a number of biological effects – antimicrobial, anti-inflammatory, antioxidant, analgesic, etc. To maintain the maximum of sensory and nutritionally valuable components of P. amboinicus, a simple maceration of fresh chopped herb was chosen. Maceration was performed under the following conditions: 40 minutes at 40 ° C, solvent 40% ethanol, weight 20 g of herb per 100 ml of solvent. The extract prepared under these optimal conditions was comprehensively characterized in terms of the content of total polyphenols, their concentration was determined to 0,08 ± 0,02 mgGEA·ml-1, which corresponds to 0,40 ± 0,07 mgGEA·g-1 of the plant. The antioxidant activity of the extract was 241,24 ± 29,24 µgTEAC·ml-1 and the radical scavenging activity of ABTS•+ was determined to be 49,29 ± 5,97 %. The antimicrobial activity was verified by the agar well diffusion method. Two types of bacteria were selected for the determination – gram-positive Bacillus cereus, gram-negative Escherichia coli and yeast Candida glabrata. The results showed that the extracts have the highest antimicrobial activity against B. cereus. There were 64 volatile aromatic compounds identified in the extract, with monoterpenes and sesquiterpenes dominating. The obtained results confirm that P. amboinicus, or its prepared extract, has a good potential for use as a new and non-traditional flavor in various foods and delicacies, which can also increase their nutritional value.
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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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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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Adsorption of toxic metals from wastewater to waste material from the food industry
Křikala, Jakub ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This thesis was focused on the possibility of secondary utilization of waste material from the wine industry to remove heavy metals from wastewater. In the theoretical part, there were discussed mainly the problems of heavy metals pollution including methods of their removal and ICP-OES detection. Furthermore, the waste material from the wine production and the possibilities of its further processing were discussed there. The primary objective of the experimental part was to characterize the material by IR analysis, optimization of adsorption conditions, isotherms construction and determination of maximum adsorption capacities of white, red and chemically modified marc for Cd, Cr, Cu, Ni and Pb. From the parameters influencing the adsorption efficiency, the adsorbent load was optimized (m/V ratio = 0,02); pH values found were 5 for Cd, Cu, Ni, Pb and 3 for Cr and the contact time to reach the equilibrium was 15 minutes for Cd, Ni, Pb and 30 minutes for Cr and Cu. Maximum adsorption capacity for heavy metals were calculated from adsorption isotherms by applying the Langmuir model and found to be 18,829 7 mg/g for Cd; 10,664 7 mg/g for Ni; 35,602 0 mg/g for Pb (modified marc with 1M NaOH); 4,678 4 mg/g for Cu and 9,629 0 mg/g for Cr. The results of the work confirm the good adsorption potential of heavy metals on marc and the positive effect of chemical modification of natural biosorbents to improve their adsorption capacity.
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