National Repository of Grey Literature 7 records found  Search took 0.01 seconds. 
Production and characterization of biochar from mixed plant waste
Bureš, Vojtěch ; Nábělek, Jakub (referee) ; Pořízka, Jaromír (advisor)
This work focused on biochar production from mixed vegetable waste in the context of home gardens and small farms. The aim of the work was to produce different types of biochar from common mixed garden waste material and then to characterize it according to the European Biochar Certificate (EBC) classification, as well as to develop a methodology for household biochar production, according to current knowledge. Four of the five biochar samples produced met all the criteria for the EBC-Feed category and are therefore suitable for any form of use, including animal feed production. The last sample did not meet the EBC parameters for usable biochar due to above-limit levels of polycyclic aromatic hydrocarbons (PAHs), but according to current studies and the new European Union limit values for fertilisers and amendments, the detected PAHs concentrations do not prevent its application to agricultural land. Therefore, based on the findings of this work, it is possible to recommend domestic production of biochar and its application to agricultural soils for long-term improvement of soil quality.
Technology for the production of wine sausage with the addition of cheese
Kejmarová, Anna ; Nábělek, Jakub (referee) ; Mikulíková, Renata (advisor)
The aim of the bachelor thesis was to investigate the effect of soft cheese on the organoleptic properties of wine sausage. Samples of wine sausages were taken before and after baking and the percentage of lipids in the sample and the content of individual fatty acids were determined using the analytical method of gas chromatography. The sensory analysis was divided into two parts. In the first part, the evaluators assessed the appearance, aroma, consistency, texture, taste, overall evaluation and balance of the cheeses. The second part focused on the overall evaluation and selection of the most flavourful samples. The data obtained from the sensory analysis were processed and evaluated using Excel. The most unpalatable wine sausage, from the results of the sensory analysis, was the wine sausage with ermine.
Determination of sweetener substitute content in chewing gum
Profousová, Sylvie ; Nábělek, Jakub (referee) ; Diviš, Pavel (advisor)
The bachelor thesis deals with the simultaneous determination of selected sweeteners in chewing gum by high-performance liquid chromatography with ELSD detection. The theoretical part is devoted to the characterization of carbohydrates and their effect on human health, classification, characterization of selected sweeteners and their use. Furthermore, a brief overview of analytical methods by which sweeteners can be determined is given. The experimental part focuses on the selection of a suitable chromatographic column for the simple identification of seven sweeteners (aspartame, acesulfame K, mannitol, maltitol, sucralose and xylitol) and the optimization of the mobile phase composition. It was found that it is not possible to determine all sweeteners by one universal method, however, using an Agilent Hi-Plex Ca column (300 x 7.7 mm) and the mobile phase of acetonitrile:water at 7:93 % v/v, it was possible to determine the concentration of (maltitol, mannitol, sorbitol, sucralose and xylitol). For the analysis of the individual sweeteners, different sample dilutions had to be used or the composition of the mobile phase had to be slightly changed. The concentration of artificial sweeteners in the chewing gum ranged from 0,35 mg/g (sucralose) to 508 mg/g (xylitol).
Production and characterization of non-chocolate sweets with the addition of plant extracts
Knapovská, Pavlína ; Nábělek, Jakub (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the production and characterization of plant extracts of green tea (Camellia sinensis) and sea buckthorn (Hippophae rhamnoides) and non-chocolate sweets – hard candies with the addition of plant extracts. These plants are characterized by a high content of bioactive substances, upon which the prepared extracts and candies were characterised. Determination of volatile substances by HSSPME-GC-MS, antioxidant activity by method with ABTS, determination of total phenols by Folin-Ciocalteu method and sensory analysis were performed. The produced sweets were then compared with similar commercial products. A total of 6 volatile substances were identified in the sample of hard candy with the addition of green tea extract, the antioxidant activity of the sample was determined to be 253,3 ± 0,9 µgml–1 and the total phenolic content was determined to be 0,49 ± 0,02 mgGAEg–1 per 1 g of candy. A total of 8 volatile substances were identified in the hard candy with the addition of sea buckthorn extract, the antioxidant activity of the sample was determined to be 206 ± 3 µgml–1, the total phenolic content was determined to be 0,51 ± 0,04 mgGAEg–1 per 1 g of candy. The obtained results show that the addition of extracts increases the nutritional value (higher antioxidant activity, higher content of phenolic compounds) of produced candy; from a sensory point of view, however, only samples with green tea were evaluated positively, the addition of sea buckthorn extract was not very attractive for consumers, they considered sweets with sea buckthorn to be too bitter.
Biologically active substances of the Gotu kola plant
Šumberová, Michaela ; Nábělek, Jakub (referee) ; Zemanová, Jana (advisor)
The Bachelor thesis focuses on the preparation and characterization of the extract of Gotu kola (Centella asiatica). The theoretical part summarizes commonly analyzed groups of biologically active compounds of herbs and introduces potential applications of the extract in food industry. Moreover, an overview of possibly used extraction methods and analytical methods for the evaluation of biologically active compounds of the extract are presented. As for the experiment, the extract of the fresh Centella asiatica herb was prepared by maceration in ethanol and then analyzed by three chosen methods. The total phenolic content of the extract analyzed by the Folin-Ciocalteu test was 0.74 ± 0.08 mgGAE·g-1. As for the quantification of antioxidant activity, the TEAC test was performed and the antioxidant activity of the extract was 289 ± 81 µg·ml-1. The volatiles present in the extract were identified by gas-chromatography mass-spectrometry in combination with solid-phase micro-extraction. Sesquiterpenoid hydrocarbons were the most dominant group of the extract, in which -farnesene (33.28 %), -caryophyllene (25.01 %), and -humulene (20.91 %) were the major compounds.
Developement and validation of method for ferulic acid isolation from wheat bran
Nábělek, Jakub ; Obruča, Stanislav (referee) ; Pořízka, Jaromír (advisor)
This master thesis deals with an optimization of processes of isolation of ferulic acid from wheat bran. Process of isolation based on alkaline hydrolysis from the substance and its adsorption was tested. In the theoretical part were described wheat bran, adsorption proces and used methods. For adsorption were tested five types of adsorbents. Especially these adsorbents: activation carbon (2,53 ± 1,16 mg.l-1), Amberlyst A-21 (105,73 ± 11,87 mg.l-1, Amberlit XAD-16 (241,55 ± 10,42 mg.l-1), Amberlit IRA-900Cl (5,90 ± 0,68 mg.l-1) and Amberlit IRA-96 (189,16 ± 6,49 mg.l-1). As the most efficient adsorbent was determine Amberlit XAD-16. The whole process has underwent detailed optimization in order to maximize the purity of the final product. The isolate was characterized by HPLC and FTIR techniques for ferulic acid and related phenolic acids. Based on FTIR analysis was discovered that the isolate was contamined by proteins. A purification procedure based on deproteination of the raw material before the hydrolysis itself was proposed. As the ultimate solution that eliminated the presence of proteins in the isolate was determine ultrafiltration with capture of molecules with Mw > 10 KDa. Ferulic acid yield from one kilo of wheat bran was 1,00 ± 0,22 g.
Characterization of different bran species in terms of ferulic acid content
Nábělek, Jakub ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This bachelor’s thesis works with an alkaline extraction of a ferulic acid from different kinds of cereal bran. Another researched issue was extraction of nutritionally interesting elements extracted from bran and from hydrolysed waste. Those extracts has possible usage as a mineral fertilizer for plants. In the theoretical part, this thesis deals with problematice of cereals, composition and differences in a cereal grain depending on kinds of cereal and an enviromental conditions. Chemical composition of cereal materials, focused on phenolic acids are also described. Another part deals with theoretical background of methods for the extraction of phenolic acids from bran with description of advantages and disadvantages. Methods for alkaline hydrolysis and extraction of minerals from different kind of bran bran are described in experimental part of this work. Sodium hydroxide (0,5 M) was used for the hydrolysis of bran material. For the determination of the yields of ferulic acid, HPLC method with UV/VIS detection at wave-length 330 nm with usage of mobile phase mixture of methanol and 0,5 % solution of formic acid was used. Acidified deionized water was used for the extraction of nutritionally interesting elements from bran and also from the hydrolyzed material. For the determination of the elemental composition of extracts (Cu, Fe, Zn, Mn, P, Ca, K, Mg), ICP-OES method was used. It was found, that differences in wheat bran species in terms of yields of Ferulic acid are satistically important. The biggest yields of ferulic acid was obtained from the sample of spelt. The smallest yields of this acic was obtained from the sample of oat. Content of micro and macro-elements showed statistical important differences in different kinds of bran and their hydrolyzed waste. Most abundand elemets were obtained from rice bran and from spelts hydrolyzate. The smallest abundand elemens were obtaned from oat bran and hydrolyzate.

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