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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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Modification and analysis of low-molecular chitosans
Moravcová, Dagmar ; Bosáková, Zuzana (advisor) ; Strašák, Tomáš (referee)
4 Abstract Chitosan is a natural biopolymer derived from chitin, found in the exoskeletons of crustaceans and fungi. It has gained considerable attention due to its biodegradability, biocompatibility, antimicrobial properties, and potential antitumor activities. Chitosan has cationic amino groups that enable interactions with various anionic compounds. Therefore, it is an ideal candidate for conjugation with monovalent bioactive compounds to form efficient multivalent conjugates. It was found that galectins, especially Gal-1 and Gal-3, are overexpressed in tumor cells. Several monovalent inhibitors derived from the parent inhibitor thiodigalactoside, also those modified with coumaryl groups, have been synthesized, which show a high selectivity and affinity towards Gal-3. The main goal of this work was to synthesize a chitosan-based carrier and conjugate it with ligands exhibiting selectivity and inhibitory effect towards Gal-3. The first step involved the modification of chitosan using a unique effective method based on solid-phase hydrolysis, which significantly reduces the consumption of chemical materials and, in addition, excessive losses during purification. At the same time, the chitosan carrier was functionalized with pentynoic acid. Furthermore, monovalent galectin ligands,...
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Extraction and application of keratin from sheep wool
Jahnová, Kateřina ; Veselá, Mária (referee) ; Kovalčík, Adriána (advisor)
This thesis deals with the isolation of sheep wool keratin for using this protein in composite films. The goal was to compare the yield of alkaline hydrolysis of sheep wool using different concentrations of sodium hydroxide. It was found that the most effective was alkaline hydrolysis using 2wt% sodium hydroxide showing 80 % effectiveness of keratin isolation. Fourier infrared spectroscopy, differential scanning calorimetry a thermo gravimetric analyses confirmed that the isolated materiál from sheep wool was keratin. The isolated keratin was used as filler for the preparation of polyvinyl alcohol-based composite films. The mechanical properties of keratin/polyvinyl alcohol films showed that keratin played the role as an active filler for polyvinyl alcohol composites.
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Production of enzyme hydrolysates from flaxseed proteins and evaluation of their properties
HAŠKOVÁ, Kateřina
This thesis focuses on effect on antioxidant properties and chosen functional properties: solubility, water and fat holding capacity, emulsification activity and stability caused by hydrolysis of protein isolates (PI) made from three different flax varieties (Libra, Agriol and Raciol). Part of this work was production of PI from flax seed. For hydrolysis trypsin, alcalase and papain were used - hydrolysis by trypsin was the mildest, while hydrolysis by papain was the most intensive one. Dynamics and degree of hydrolysis were also observed. Solubility of PI and hydrolysates was discovered to be very high (almost 100%). On the contrary water holding capacity was lower (3,93 g/g and less) than fat holding capacity (4,34 g/g), which increased upon hydrolysis for most enzymes, while water holding capacity decreased. Emulsification activity rised (1,47×) under the effect of hydrolysis, however stability dropped (1,3×). The best emulsifiction properties were found out in trypsin hydrolysates. Hydrolysis caused great impact on content of polyphenols which were in alcalase hydrolysates up to 3× higher and on antioxidant activity which grew in papain hydrolysates up to 2,5×.
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Mechanistic Insights into Reactive Zeolite-Water Interactions
Benešová, Tereza ; Heard, Christopher James (advisor) ; Maldonado Dominguez, Carlos Mauricio (referee)
Title: Mechanistic Insights into Reactive Zeolite-Water Interactions Author: Tereza Benešová Department: Department of Physical and Macromolecular Chemistry Supervisor: Christopher Heard, PhD. Abstract: An in silico investigation of zeolite-water interactions was undertaken using a combined static and dynamic approach within density functional theory. Two periodic models of zeolite chabazite were used, purely siliceous and aluminosilicate in order to explain the different behaviour of water near Si-O-Si and Al-O-Si bridges. One or two water molecules per supercell of the model were used, corresponding to experimental conditions of steaming. Under such conditions, water can interact with zeolites by non-reactive adsorption but also by reactive interactions such as hydrolysis and oxygen exchange between water and the framework. The main goal of the study was to explain oxygen exchange at an atomistic level. The viable mechanisms of oxygen exchange were established. These mechanisms are different for Si-O-Si and Al-O-Si bridges but for both of them oxygen exchange is initiated by partial hydrolysis of the framework. After this hydrolysis, oxygen exchange heals the framework while incorporating into it the oxygen that originated from the water. Both established mechanisms are competitive with non-exchange...
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Theoretical Investigation of the Zeolite Hydrolysis under Realistic Conditions
Jin, Mengting ; Grajciar, Lukáš (advisor) ; Chizallet, Céline (referee) ; Piskorz, Witold (referee)
Zeolites are one of the most widely used and one of the most industrially important materials. They are utilized in a variety of commercial applications, particularly in heterogeneous catalysis, adsorption/separations applications and as ion exchangers. Zeolites are stable when exposed to water or water vapor at ambient conditions and exhibit high thermal stability. However, zeolites can be partially or even fully hydrolyzed under certain conditions. This hydrolytic instability of zeolites can be considered both a major problem in some applications and a useful means to tune catalyst properties in the others. However, the thorough studies of the hydrolytic mechanisms under realistic conditions (high water loading, alkaline conditions, high heteroatom concentrations, etc.) and employing realistic models (dynamical simulation of ab initio accuracy) is mostly lacking. This dissertation uses the ab initio calculations to systematically study the hydrolysis mechanism of zeolites under realistic conditions, including: (1) hydrolysis mechanism of germanosilicate zeolite UTL, (2) hydrolysis of siliceous zeolite CHA under alkaline conditions, and (3) identification of the nature of framework-associated Al(Oh) species in aluminosilicate zeolite CHA under wet conditions. The main results obtained are as...
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Templating as a new method of creating and modifying the porous texture of polyacetylene networks
Sokol, Jiří ; Sedláček, Jan (advisor) ; Balcar, Hynek (referee)
A new method of introducing permanent micropores into hyper-cross-linked polyacetylene networks has been developed. The method used a combination of polyacetylene chemistry and Schiff base chemistry. Through the coordination chain-growth polymerization of monomers with polymerizable ethynyl groups, a wide series of homopolymer and copolymer networks with rigid polyene main chains interconnected by arylene links was prepared. The networks carried substituents of the predominantly aromatic Schiff-base-type in the pendant groups. With increasing content and volume of these substituents the specific surface area of the networks decreased. The networks with a high content of Schiff-base-type substituents were non-porous. The prepared networks were subsequently hydrolyzed under the conditions optimized in this diploma thesis. The hydrolysis led to a highly efficient cleavage of the Schiff base methanimine linkages and to the removal of the cleaved low molecular weight aromatic amine and aldehyde segments from the networks. In this way, new functional groups were generated in the networks, either CH=O or NH2. The hydrolytic modification had a fundamental effect on the texture parameters of the networks. The modification of the originally microporous networks mostly led to an increase in the specific...
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Measurement of viscosity of suspensions during wheat bran processing
Koukal, Jan ; Slavíková, Zuzana (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the assessment of the viscosity evolution of wheat bran suspension during alkaline hydrolysis. Wheat bran is a widely produced low-cost by-product of the milling industry. Due to its composition, bran is a suitable substrate for biorefining and involvement in the circular economy. However, during processing, viscosity development occurs, which greatly affects the energy requirements for processing. The temporal evolution of viscosity during alkaline hydrolysis was determined using a rotational rheometer at constant shear rate. Viscosity was assessed as a function of NaOH concentration, temperature and bran ration. Furthermore, the evolution of viscosity was measured during alkaline extraction of proteins. The highest viscosity was measured in a 0.2 M NaOH system at 30 °C with a bran to hydroxide ratio of 1:10. Its value was 0.991 ± 0.010 Pa.s. Based on the theoretical part and the data obtained from rheological measurements, the design of a stirred reactor for wheat bran processing on an industrial scale was carried out. It is a vertical cylindrical vessel with a total volume of 10 m3. The vessel is equipped with three Chemineer HE-3 hydrofoil impellers mounted on a vertical shaft. The power input of the agitator was calculated at 2.8 kW and compared to a conventional 4-blade, 45-degree pitched blade turbine, the chosen design was four times more efficient.
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Preparation and characterization of packaging films based on beta-keratin
Měšťánková, Zuzana ; Mikulíková, Renata (referee) ; Kovalčík, Adriána (advisor)
This diploma thesis deals with keratin isolation from poultry feather waste and preparation of keratin-polymers composite films utilizing isolated keratin. The main goal was to isolate keratin from poultry feathers by hydrolysis and compare yield of diverse hydrolysis types. The most efficient was hydrolysis using 0.5% sodium hydroxide with yield 480 g of keratin per 1 kg of chicken feathers. Structure, morphology and thermal properties of isolated keratin was analyzed. Comparison with protein molecular weight standard it was revealed that hydrolysis cleaved keratin to macromolecules smaller than 15 kDa. Scan electron microscopy showed that size of lyophilized keratin particles was in the order tens of µm and had an irregular shape. Further, composite films based on isolated -keratin and other polymers were prepared. Thermal analysis showed, the addition of keratin significantly reduced the thermal stability of composite films. Analyses revealed that Polyvinyl alcohol composite films reached the best mechanical properties. For example, an addition of 0.25 g of keratin per 1 g of polyvinyl alcohol increased the tensile elongation by up to 68.9%. Moreover, the film based on chitosan and keratin had antibacterial properties. The results demonstrate that it is able to efficiently isolate keratin from poultry feather waste by alkaline hydrolysis and isolated keratin can be utilized to prepare potentially applicable keratin-polymers composite films.
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