National Repository of Grey Literature 13 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Development of organic UV filtres based on natural extracts
Káčeríková, Martina ; Kovalčík, Adriána (referee) ; Márová, Ivana (advisor)
This diploma thesis is focused on the development of organic UV filters. Organic UV filters were extracted from natural resources and encapsulated into nanomaterial-like delivery systems such as liposomes and nanofibres. SPF of particular extracts and carriers with encapsulated extracts were measured. All of the prepared extracts as well as carriers were characterised for their content of natural substances like phenolic compounds and their antioxidant acitvity, stability, cytotoxicity, micriobial acitivity and their safety were studied too. All of the prepared materials were evaluated as suitable for use in comestic industry. However, in a future, it would be appropriate to add to the study other experimental methods to increase the active substances and at the same time increase the SPF protection factor.
Biodegradation of bioplasts in compost environment
Vodička, Juraj ; Kovalčík, Adriána (referee) ; Obruča, Stanislav (advisor)
This master’s thesis focuses on biodegradation of polyhydroxybutyrate (PHB) and polylactic acid (PLA). The theoretical part discusses an origin, properties and applications of investigated biopolyesters, and so the enzymology of their biodegradation. The experimental part deals with biodegradation of these polymers in liquid medium using several pure thermophilic bacteial strains and controlled composting of these bioplastics. Amongst six tested thermophilic bacterial strains only one showed PHB-biodegradation activity – strain Schlegelella thermodepolymerans. No degradation degree of amorphous or semi-crystalline PLA was observed. Mainly disintegration of both forms of PLA articles was observed in compost environment, thus the abiotic mechanism of its decomposition was indicated. After 4 weeks of composting, the relative weight loss of 99 % and 63 % was detected in amorphous and semi-crystalline PLA respectively. On the contrary, the weight loss of PHB after 4 weeks of composting reached 36 %, moreover, a half decrease of molar mass was observed using SEC. The surface erosive mechanism of PHB-biodegradation was stated using SEM. By monitoring of esterase, lipase and protease activities, no influence on the compost by polymer presence was concluded at statistical significance.
Isolation of lignin from grape seeds and its application as filler for polyhydroxyalkanoates (PHA)
Vostrejš, Pavel ; Vítová, Eva (referee) ; Kovalčík, Adriána (advisor)
This diploma thesis deals with 1) the preparation of biodegradable polymer films based on polyhydroxyalkanoates (PHA) and 2) their modification by lignin as an active additive. The motivation for this work was to prepare active packaging material for food packaging. Polymer films were prepared by blending of neat crystalline poly(3hydroxybutyrate) (P3HB) and amorphous polyhydroxyalkanoate (PHA). The lignin was isolated from grape seeds derived from grape pomace. The solubility of lignin in chloroform was improved by acetylation. The properties of the isolated lignin were determined by elemental analysis, ash content, and infrared spectroscopy (FTIR). Lignin was used as an active additive for the modification of polymeric films prepared by solution casting of P3HB or P3HB blended with amorphous polyhydroxyalkanoate. The effect of different concentrations of lignin in the range of 1 to 10 % was tested. The lignin type and concentration had a different influence on the final thermal and mechanical behaviour of polymeric films. Lignin increased the values of the Young modulus and tensile strength of the prepared films. Differential scanning calorimetry data confirmed that lignin positively modified crystallization kinetics of P3HB. Thermogravimetry was used to analyse the thermal stability of PHA films. Lignin markedly increased the thermal stability of PHA films. However, acetylated lignin harms the mechanical properties of films. Moreover, this work showed that lignin isolated from grape seeds and added into PHA films proved its high antioxidant capacity. PHA films with lignin displayed much better gas barrier properties compared with PHA films without lignin. The prepared bioactive PHA films fulfil the requirements for sustainable food packaging with high antioxidant capacity and excellent gas barrier properties.
Volatile profile of Edam type cheese
Balej, Marek ; Kovalčík, Adriána (referee) ; Vítová, Eva (advisor)
This bachelor thesis is focused on specification volatile profile of eidam cheese types, which are natural semi hard cheeses with low heat curd. Subject of theoretical part is basic differentiation of cheeses, description of chemical composition and characteristic of eidam cheese types. After that, issue of their manufacturing process is processed and aroma active substances are described. In the last part of this section, the attention is focussed on specification method of solid phase microextraction connected with gas chromatography with mass spectrometry detection. Experimental part deals with HS-SPME-GC-MS method application on identification of volatile compounds in eidam cheese types. Samples of model cheese were manufactured at Tomas Bata University in Zlín with the use of various added microbial starter cultures and eidam type cheeses with various fat content bought on the market. A total of 64 compounds were identified in samples; of those 18 alcohols, 11 esters, 9 ketones, 7 aldehydes, 5 acids, 3 lactones, 2 terpene hydrocarbons, 2 terpene alcohols, 1 terpene ketone, 1 terpene aldehyde, 4 sulphurous compounds and 1 phenol. The differences were found among model cheese samples and market bought samples in the case of number and type of volatiles.
Production of PHB-HV from grape pomace by employing a pure culture of Cupriavidus necator
Jakešová, Michaela ; Kučera, Dan (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis deal with the production of PHB-HV copolymer employing a pure culture of Cupriavidus necator H16. First, Erlenmeyer flask´s cultivations using pure fructose as a source of carbon were performed. The mode of addition of valeric acid for the synthesis of PHB-HV was studied. Furthermore, the effect of stress factor (ethanol) on PHB-HV synthesis by this microorganism was investigated. The method obtained by optimization in Erlenmeyer flasks was applied to the synthesis of the PHB-HV copolymer in the bioreactor using fructose as a source of carbon, too. Furthermore, after enzymatic hydrolysis, a sugar extract from grape pomace was obtained as a source of carbon for the synthesis of PHB-HV. The fermentation in Erlenmeyer flasks and the bioreactor using an extract of grape pomace was carried out. Using this alternative carbon source 3.51 g/l PHB-HV copolymer was produced in Erlenmeyer flask, 5.06 g/l in bioreactor respectively. In the first case, the proportion of 3-hydroxyvalerate in the copolymer was 23.78 mol. % and in the second one, 9.39 mol. %.
Evolutionary engineering of PHA producing bacterium Halomonas halophila
Ikrényiová, Terézia ; Kovalčík, Adriána (referee) ; Obruča, Stanislav (advisor)
This bachelor thesis deals with evolutionary engineering of PHA producing bacteria, the principle of PHA production and solution of this production’s disadvantages, but also applications of these biopolymers in the theoretical part. The production of polyhydroxyalkanoates by bacteria Halomonas halophila, which is focused on gaining the maximus amount of 3-hydroxyvalerate in formed copolymer, is described in the experimental part. The precursor valeric acid was added to bacteria due to gain the amount of 3HV. It was found that the concentrations over 3 g/l aren´t usable for production sufficient concentration of PHA. The very low concentrations of valeric acid led to low amount of 3HV in PHA. The available concentration of this precursor for production sufficient concentration of PHA by bacterial cell is 3 g/l. Moreover, it was found that the valeric acid should be added after 24 hours of cultivation in mineral production medium. The thesis is also concentred on comparison the original bacterial strains of Halomonas halophila to strains, which were adapted on valeric acid as stress factor for bacteria. The assumption, that the adapted strains can better utilize valeric acid and the incorporation to copolymer of it is higher like the original strains, was affirmed.
Evaluation of grape pomace as carbon source for bacterial cellulose production
Stříž, Radim ; Obruča, Stanislav (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis is focused on the production of bacterial cellulose by Gluconacetobacter xylinus. The theoretical part consists of a brief description of G. xylinus, properties and uses of bacterial cellulose. Firstly, the experimental part focuses on optimization of production of bacterial cellulose by G. xylinus CCM 4611. This optimization was focused on pH value, a cultivation type, and used carbon source for production. The optimal pH was 6.5. The carbon source showing the highest production of bacterial cellulose was mannose for the dynamic production and saccharose for the static production of bacterial cellulose. The second part of the experimental part focuses on a comparison of two methods for assaying reducing sugars – Somogyi-Nelson (SN) assay and dinitrosalicylic acid (DNS) assay. The comparison of two above mentioned methods showed that the results obtained by the SN method were very close to High performance liquid chromatography (HPLC) data. It can be concluded that HPLC method is the best method if we need to know the type of sugars but if we need only the quick determination of the sum of the reduction sugars, SN method is very suitable. 4 It can be concluded that the Moravian region produces a large amount of winery biomass. Therefore, the use of the pomace extract as a carbon source for the production of bacterial cellulose seems to be interesting mainly from the point of the recirculation economy. The obtained results showed that the grape sugar extract could be used, and from the production values, it is even more suitable for the production of bacterial cellulose than industrial sugars.
Refinery and characterization of grape oil
Prchal, Miroslav ; Vítová, Eva (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis deals with the topic concerning the extraction of wine oil from grape seeds, the refining of the extracted oil and the characterization of grape oil. Grape oil was extracted from the grape seeds obtained from the harvest in September 2019 by the winery Vavricek (Brezi u Mikulova, Czech Republic). The received grape pomace was the mixture of Green Veltliner and Blanc Saugvinon. The oil was extracted from the separated seeds by using liquid extraction in n-Hexane. The extraction yields of grape oil were compared with the literature, involving the different extraction methods as well as different oil plants. For the refining of the grape oil have been applied more steps aiming for the removal of the lipophilic pigments. Different adsorbents of pigments have been applied. The purification efficiency has been proved by the investigation with the thin layer and the high-performance chromatography. Moreover, the gas chromatography was used to characterize the composition of the oil. Finally, the composition profile of the oil obtained by the liquid extraction before and after purification has been compared with the commercial grape oil, which has been received by cold pressing. The results of the work show that the winery waste produced in South Moravia is a valuable raw material, which can be used for the production and different products, e.g., grape oil and pigments (chlorophyll).
Changes in gliadin content in four varieties of wheat at different temperatures and drought stress.
Cigánková, Michaela ; Kovalčík, Adriána (referee) ; Hrstka, Miroslav (advisor)
This diploma thesis deals with an influence of increasing temperature and water shortage on the content of gliadin proteins in four varieties of wheat: Bohemia, Pannonia, Tobak and RGT Reform. Samples were cultivated at 26, 29, 32, 35, 39 and 41 ° C. Due to the lack of culture samples at 41 ° C, these samples were not used for our experiment. Cultivation took place during flowering with sufficient moisture (with soil moisture higher than 70%) or under drought stress (with humidity below 30%). The A-PAGE method was used to separate gliadin fractions. Quantification was performed by computer densitometry. Significant influence of water availability on gluten protein content was found. The lack of moisture in the stress environment caused a relative increase in gliadin fractions compared to conventional conditions, especially in the Pannonia and RGT Reform varieties. The Pannonia and RGT Reform varieties responded most to the temperature, while Bohemia. The Tobak variety responded to the temperature in interaction with water scarcity. Due to the rising temperature, virtually all gliadin fractions in the Pannonia and RGT Reform varieties increased. The effect of drought often manifests itself in interaction with the influence of temperature. The most dramatic effect was the drought in interaction with temperature in the Tobak variety, where the gliadin content increased. In general, the temperature and drought were most affected by -gliadin fractions of all four varieties of wheat.
Biotechnological production of PHA employing Cupriavidus malaysiensis
Drábková, Kateřina ; Kovalčík, Adriána (referee) ; Obruča, Stanislav (advisor)
The subject of this diploma thesis is the study of the production of polyhydroxyalkanoates (PHA) employing Cupriavidus malaysiensis. The aim of this thesis is to obtain and characterize the polymer with the most advantageous properties. The theoretical part deals with polyhydroxyalkanoates and their biotechnological production. Then selected microorganisms producing 3-hydroxybutyrate and 4 hydroxybutyrate, P(3HB co 4HB), are described. After that, the theoretical part deals with the production of PHA employing Cupriavidus malaysiensis. The bacterial strains of Cupriavidus malaysiensis DSM 19416, 19379 and 25816 were used in the experimental part. The strain Cupriavidus necator H16 was used as a control strain. First, the ability to utilize various carbon sources by the given bacterial strains was determined. Then, the aim was to select the optimal carbon source, a precursor for the synthesis of a polymer with high content of 4-hydroxybutyrate, and to determine the ideal culturing conditions for the growth of the microorganisms, which have been studied, and the production of P(3HB co-4HB). A two-stage culture and bioreactor culture was also performed to produce the desired copolymer. Furthermore, the production of terpolymer of 3-hydroxybutyrate, 4 hydroxybutyrate and 3-hydroxyvalerate, P(3HB co 4HB co 3HV), was studied by single stage and two-stage cultivation. In the last part, the produced polymers were characterized by gas chromatography with flame ionization detector (GC-FID), size exclusion chromatography with multi-angle static light scattering (SEC-MALS), differential scanning calorimetry (DSC) and thermogravimetry.

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1 Kovalčík, Andrej
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