National Repository of Grey Literature 358 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Stanovení obsahu karotenoidů u vybraných druhů mikrozeleniny
Otrusinová, Kateřina
The thesis focuses on the content of carotenoids (β-carotene and lutein) in 14 species of microgreens. Although microgreens are small in size, they are distinctive in taste, colour and health benefits. The results showed that different types of microgreens contain very different amounts of β-carotene and lutein. The β-carotene content ranged from 1.55–4.82 mg / 100 g fresh microgreens, while the lutein content ranged from 2.33–8.01 mg / 100 g fresh microgreens. Comparing the measured values in microgreens with the concentrations of these carotenoids in mature vegetables found in the literature, microgreens are often a richer source of β-carotene and lutein. Since carotenoids are biologically active substances with strong antioxidant capacity, the comparison of the content of these pigments in different types of microgreens is essential for the food industry and for the consumers.
Oligomerization state and pigment contents of algal light-harvesting proteins
MALINOVÁ, Kateřina
Light-harvesting antennas (LHCs) from four microalgae species (diatom Phaeodactylum tricornutum, haptophyte Emiliania huxleyi, and two eustigmatophytes Nannochloropsis oceanica and Trachydiscus minutus) were studied. LHCs were extracted and purified using sucrose gradient ultracentrifugation and ion-exchange chromatography. Oligomerization states of LHCs were assessed using two independent methods - CN-PAGE and size-exclusion chromatography. Effects of the purification on LHC pigment composition was assessed using HPLC.
The development of an HPLC method for monitoring the preparation of oligodeoxynucleotide probes
Šemlej, Tomáš ; Kučera, Radim (advisor) ; Pilařová, Pavla (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Chemistry and Pharmaceutical Analysis Candidate: Mgr. Tomáš Šemlej Supervisor: doc. PharmDr. Radim Kučera, Ph.D. Title of rigorosum thesis: The development of an HPLC method for monitoring the preparation of oligodeoxynucleotide probes An artificially prepared oligodeoxynucleotide sequence with the attached label is referred to as a molecular probe. Molecular probes are mainly used to quantify multiplication in RT-PCR and identify mutations in PCR analyses. There are typically two different types of probes - mono-labeled molecular probes and double-labeled molecular probes. The mono-labeled molecular probes are constructed from fluorophore- labeled oligodeoxynucleotide sequence or quencher-labeled oligodeoxynucleotide sequence. Whereas double-labeled molecular probes consist of an oligodeoxynucleotide sequence with a fluorophore attached at one end together with a quencher attached at the other end of the chain. In this work, we first paid attention to the separation of double- labeled oligodeoxynucleotides from mono-labeled oligodeoxynucleotides. Several types of stationary phases were tested and based on that the column Clarity® Oligo-RP™ was chosen to separate a mixture of labeled oligodeoxynucleotides. This...
Determination of propyl gallate on carbon paste electrode
Vysoká, Marie ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
Propyl gallate (PG) is a significant synthetic antioxidant and preservative. Its determination has been studied at carbon paste electrode (CPE) using differential pulse voltammetry (DPV) and high performance liquid chromatography with electrochemical detection (HPLC-ED) and with UV spectrometric detection (HPLC-UV). Concentration dependences were measured in the media of Britton-Robinson buffer (pH 5) and methanol (20 %, v/v) by DPV and the limit of detection 0,6110-7 moldm-3 was obtained. Using HPLC with a mobile phase consisting of 0,01 moldm-3 phosphate buffer (pH 4) and methanol (50 %, v/v) with potential of working electrode E = +0,8 V and detection wavelength λ = 280 nm, concentration dependences were measured. Limit of detection was determined to 0,39 moldm-3 for HPLC-ED and 4,95 moldm-3 for HPLC-UV. After verification of the extraction procedure PG was determined in vegetable oil. The resulting value of 3,2 mgkg-1 corresponds with permited limits.
Determination of bisphenols in selected beverages by high-performance liquid chromatography
Marvan, Jiří ; Sobotníková, Jana (advisor) ; Olšovská, Jana (referee)
Bisphenols are chemical compounds with a wide range of uses in the chemical industry. They are used in the production of plastic materials as softeners for polymer materials or epoxy resins, as monomers in the synthesis of polycarbonates, or for the elimination of hydrochloric acid in the production of polyvinyl chloride. This thesis deals with the development, validation, and optimization of an analytical method for the determination of selected bisphenols, specifically bisphenol A, bisphenol B, bisphenol F, bisphenol A diglycidyl ether and bisphenol F diglycidyl ether (BPA, BPB, BPF, BADGE, BFDGE), and their metabolites using the high performance liquid chromatography with mass spectrometry, HPLC/MS, and the application of the method to real samples in selected canned beer samples. The following conditions were optimized for chromatographic separation. The Sigma-Aldrich discovery C18 column (150×2,1 mm, 5µm) was chosen. The mobile phase consisted of a mixture of mobile solvent A, which contained 0,05% ammonium hydroxide, and mobile solvent B, which contained of methanol. The flow rate of the mobile phase was 0,240 ml/min. The total analysis time was 22 minutes, using a 5 μl injection of the sample solution with gradient elution. Next, a partial validation of the method was performed, evaluating...
Study of selected mushroom toxins of Amanita muscaria.
Adámek, Michal ; Bosáková, Zuzana (advisor) ; Hložek, Tomáš (referee)
The presented bachelor's thesis was focused on the development of an HPLC-MS/MS method for the separation and eventual quantification of the main toxins of Amanita muscaria (fly agaric). After optimization of tandem mass detection conditions, MRM transitions were found for muscarine (174 → 57), ibotenic acid (159 → 113), muscimol (115 → 98) and cycloserine (103 → 75), which was used as an internal standard. Measurements were performed on Luna Omega 1.6 µm polar C18 column in RP-HPLC mode with an optimized mobile phase composition of 2:98 (v/v) acetonitrile/deionized water with the addition of 0.1% formic acid in both components and Ascentis Express RP- Amide in HILIC mode with an optimized mobile phase composed of 70:30 (v/v) methanol/deionized water with the addition of 0.5% formic acid in both components. Calibration curves with a range of 0.01 to 10 µg/ml for RP-HPLC and 0.01 to 25 µg/ml for HILIC were measured under optimized conditions. Urine and blood serum solutions of a patient with Amanita muscaria poisoning, including diluted versions of these solutions, were measured. Ibotenic acid and muscimol were found in the patient's urine, muscarine, ibotenic acid and muscimol in the blood serum. The RP-HPLC method gave narrower peaks with lower retentions and lower noise levels. The studied toxins...
Testing of the electrochemical properties of flow-through diamond detector
Pecák, Jakub ; Dejmková, Hana (advisor) ; Vyskočil, Vlastimil (referee)
In the presented bachelor thesis, the functionality of a flow-through multitubular boron- doped diamond electrode (mtBDDE) was verified on two selected neurotransmitters, DA and NE, using the HPLC technique with isocratic elution. An aqueous solution of Britton-Robinson (B-R) buffer was chosen as the mobile phase and a Kinetex EVO C18 reverse column (150 x 4.6 mm) as the stationary phase. The flow rate of the mobile phase was set at 1 ml/min. For electrochemical detection, mtBDDE was used and UV detection at 280 nm was applied as an assistant to the main detector. The electrochemical response of the DA and NE solution (cΘ = 1.10-4 mol/dm3 ) was investigated in the form of hydrodynamic voltammograms over a potential range from 0.1 V to 1.3 V in different pH ranges of the mobile phase (2.5; 4.0; 6.0; 8.0 and 10.0). It was found that the potential wave shifts to lower potentials with increasing pH of the mobile phase, while the response of individual analytes does not change significantly with pH. Under optimal conditions, i.e., mobile phase B-R buffer at pH = 6 and a potential loaded on the mtBDDE of 0.6 V, the repeatability and reproducibility of the measurement results were verified. The electrode gave repeatable results (RSD < 4 %) comparable to the UV detector used (RSD ≤ 4 %) over the series of...
Active preparatives based on koji fermentation and medical mushrooms extracts
Živná, Kristýna ; Dzurická, Lucia (referee) ; Hoová, Julie (advisor)
This bachelor's thesis deals with the optimization of the growth of the rare species fungus of the hedgehog mushroom on cereal substrates for the purpose of the subsequent to cultivation of lactic acid bacteria. The theoretical part is focused on the description of the rare fungus species and the use of the cereals as substrate and the characterization of their active substances. It also deals with lactic fermentation and its use. In the experimental part, the preparation of the cereal substrate for the cultivation of the hedgehog mushroom was optimized. The method of inoculation of the cereals substrate with liquid mycelium in combination with plate mycelium was chosen as the most applicable. In this combination, the substrate does not dry out and grows evenly from both sides of the substrate. The composition of the cereal substrate with grown mycelium was characterized (antioxidant activity, carbohydrates, proteins). Finally, the substrate was inoculated with lactic bacteria. The lactic bacteria added nutritional value to the product. Fermentation products (antioxidant activity, carbohydrates, proteins) were characterized, and bacterial viability was analysed.
Development of methods for determination of authenticity of cosmetic products with a plant component
Langová, Denisa ; Brázda, Václav (referee) ; Vorlová, Lenka (referee) ; Márová, Ivana (advisor)
In the final thesis, methods were developed for determining the authenticity of cosmetic products and food products with a plant component. The presence of natural ingredients in a series of model and commercial cosmetic products was verified and their authenticity was verified, too. The focus of the work was the development of a molecular-biological method for the detection of plant components (herbs, fruits, essential oils) and probiotics present in cosmetic products. Commercially available isolation kits were used for the isolation of DNA from cosmetic products and the method was optimized for the isolation of plant DNA present in cosmetic products. The presence of a plant matrix in cosmetic products was detected by the polymerase chain reaction (PCR) method. Instrumental methods were used to detect the presence of fragrance allergens in cosmetic products. A method of quantifying these allergens using liquid chromatography was introduced and the measurement results were compared with the results of gas chromatography with mass detection. The proposed method of isolation and subsequent amplification of plant DNA is suitable for determining the authenticity of herbal ingredients in cosmetic products. The proposed HPLC method is a simple and inexpensive method suitable for determining the allergens present in the amount necessary to comply with EU analyte legislation and in the required sensitivity (except for hydroxycitronellal). Both methods are suitable to be used for the analysis of food products, too.
Bioflavouring of low alcoholic beer by dry hopping
Dušánek, Václav ; Mikulíková, Renata (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the influence of cold hopping of low-alcohol beers on analytical properties and sensory profile of beer. The effect of cold hopping was observed using the varieties Kazbek, Jazz, Mimosa and Uran. In the experimental part, the production process of low-alcohol beer using immobilized yeast is described. After the main fermentation, the low-alcohol beer was kegged into five cuvettes and after 20 days cold-hopped at a dose of 3 g/l with individual varieties. The effect of cold hopping with individual varieties on the organoleptic properties of the beer was observed. Bitterness was determined, with cold-hopped beers showing an increase between 17-24 % in bitterness. Furthermore, the ethanol content was determined by high-performance liquid chromatography at 2,14 % vol. A significant increase in all volatiles, in particular -myrcene and linalool, was found in the cold-hopped beers by gas chromatography with mass spectrometry. The sensory analysis showed that the cold hopping had a positive effect on the overall impression and masked the taste defects of the reference low-alcohol beer. The best hop evaluated for the use of the cold hopping method was the Kazbek variety. The Jazz and Mimosa varieties were also perceived relatively positively by the evaluators. On the other hand, the Uran variety achieved a worse overall impression than the reference beer.

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