National Repository of Grey Literature 7 records found  Search took 0.00 seconds. 
Use of analytical methods and chemometry to verify the geographical authenticity of honey
Marková, Lucie ; Křikala, Jakub (referee) ; Diviš, Pavel (advisor)
The teoretical part of this bachelor thesis is focused on the process of producing the honey by bees, its composition and means of its adulteration or ways to detect substandard products. The experimental part describes methodes, which were used to observe the samples. Sacharides, organic acids, mineral content, the amount of dry matter, titration acidity and conductivity were meassured. Obtained data were used for differentiation the Czech and foreign honey. The result of the statistical analysis shows the calcium, copper and glucose content are suitable paramteres to differentiate the Czech honey from that externals. Theese parameters could be used to distinguish the two different geographical origin of honey. Nevertheless, the total evaluation seems to be insufficient for differentiation these two groups. The efficiency could be icreased by the including more samples for analysis, or meassuring more parameters. Finally, some of the parameters were used for quality control of honey.
Characterization of lipids in fresh cheeses
Vaňková, Veronika ; Křikala, Jakub (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the determination of fatty acids in samples of fresh cheeses with or without the addition of plant extracts (rhyme, echinacea), produced in laboratory conditions at FCH BUT. The theoretical part of the thesis focuses on the general characterization of lipids and fatty acids. The next part discusses the characterization, division, and methods of cheese production, focusing mainly on fresh cheeses. The end of the work is devoted to gas chromatography as a method for the determination of fatty acids in cheese samples. The experimental part aimed to determine the content of fatty acids in the samples of fresh cheese. For the extraction of lipids from cheese samples, the choice of the method was according to ČSN EN ISO 1735. Acid esterification with boron trifluoride as a catalyst was used for the preparation of fatty acid methyl esters. The determination of fatty acid methyl esters was performed by gas chromatography with a flame ionization detector (FID). A total of 14 fatty acids were identified in all samples in a bound and free form. Myristric, palmitic, stearic and oleic acids predominated in all samples, which is in agreement with the knowledge of the composition of milk fat. The obtained results show, that even due to slight differences in the content of individual fatty acids, the addition of extracts does not affect the composition of fatty acids in fresh cheeses.
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.
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.
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.
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.
Study of utilization of waste material from the food industry for the removal of metals from waste waters
Křikala, Jakub ; Obruča, Stanislav (referee) ; Diviš, Pavel (advisor)
In this bachelor thesis is discussed the potential use of the marc from the wine production for the removal of metals from wastewaters. Marc containing stems, peels and seeds without any prior chemical treatment were homogenized and rinsed with distilled water to remove soluble impurities. IR spectrometry was used for characterization of the major functional groups responsible for the adsorption of metal ions. The experimental part of this work consisted of the assessment of the optional pH value for adsorption of copper and the maximum adsorption capacity of the used material in column and batch method. The results show that the optional pH values for adsorption of copper were in the range pH 3 – 4. Maximum adsorption capacity were calculated form adsorption isotherms by applying the Langmuir model and found to be 0,260 4 mg/g Cu at a column method and 1,246 2 mg/g Cu after 30 minutes the batch adsorption method. Further, it was experimentally demonstrated that the adsorption of copper in addition to the pH depends also on the initial copper concentration in the solution, contact time and other parameters whose optimization would achieve greater adsorption capacity of the referred material. The results indicate that the marc from the wine production have good potential form removing metals from wastewaters by adsorption.

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