National Repository of Grey Literature 57 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Production and characterization of protein isolates from different kinds of bran
Vybíral, Lukáš ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with the use of various types of bran as a by-product in the milling of cereals. Mills create a huge amount of this material per year. The most common way of processing bran is mostly incineration and to a lesser extent it is used as feed for livestock. Depending on the type of cereal, bran contains 10-20% of protein, which disappears from the food chain due to combustion. Within the framework of sustainability and valorisation of waste, which has recently been largely discussed, great emphasis is placed on waste minimization whether in the field of its production or further processing. Due to the relatively high protein content, bran appears to be a suitable starting material to produce protein supplements. Proteins can be extracted from bran based on their different solubility at different pH. In the alkaline method, the proteins are first dissolved in an alkaline pH and then precipitated in an acidic medium. Lyophilization is followed by characterization of the extract in terms of yield, protein content, moisture, amino acid profile and digestibility. The highest yield was obtained with the oat bran isolate (13,5 ± 0,6 g of isolate per 100 g of bran). In terms of protein content, the best protein isolate was also obtained from oat bran (95,2 ± 0,4% protein in the isolate). Another determination was the analysis of the amino acid profile, in which a high content of arginine was found in all analyzed protein isolates from bran. Determination of digestibility showed very good digestibility of all produced protein extracts from bran.
Isolation of pure aminoacids from wheat bran
Sloupová, Klára ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
Wheat bran is a promising material containing a wide range of useful components, including proteins. In addition, it is produced in significant volumes. Currently, wheat bran is used for the production of energy by combustion and for feed purposes. Gradually, new methods of valorization of this material are being sought. One of the possibilities of using wheat bran is the isolation of proteins, hydrolysis, and separation of selected amino acids. This diploma thesis deals with this issue, it is focused on the recovery of arginine and leucine from a protein isolate. Proteins were extracted from wheat bran by changing the pH. Thanks to the subsequent lyophilization a protein isolate was gained. Prior to hydrolysis of the resulting isolate, a stability test of arginine and leucine amino acid standards was first performed, to which various hydrolysis methods were applied. Acid hydrolysis using a mineralizer, which was applied to the protein isolate, was proved to be the most effective. This was followed by the derivatization of the hydrolysates with OPA and analysis of the resulting hydrolysates by high-performance liquid chromatography with UV-VIS detection. Then, suitable adsorption and desorption conditions were optimized. It was found that the time dependence does not affect the amount of adsorbed material on the sorbent. Therefore, an application time of 15 minutes was chosen. While optimizing the amount of used standard, it was found that the optimal weight was 0.25 g of sorbent. The selected conditions were applied to the protein hydrolyzate. Two fractions were obtained by the separation of selected amino acids due to the change in the pH of the citrate buffer. After the application of this procedure, 0.26 g of arginine and 0.82 g of leucine were obtained from one kilogram after evaporation. From evaporation two, 1.01 g of arginine and 0.25 g of leucine were obtained after evaporation.
Biologically active substances of chokeberry (Aronia spp.)
Palkovská, Kateřina ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
This master thesis deals with preparation of extracts from fruits of aronia, optimization of conditions for extraction and subsequent characteristics of the obtained optimal extract. In the theoretical part information about the botanical characteristics of Aronia melanocarpa and about its utilization are mentioned. Furthermore, the chemical composition of aronia fruits is described and the main biologically active substances contained in the plant are described. At the end of the theoretical part extraction and separation techniques, determination methods of antioxidant, antimicrobial activity and determination of aromatic active compounds are described. The experimental part describes the optimization of maceration so that the macerate contains as much polyphenolic substances as possible, as well as aromatic active substances. 40% ethanol, at a temperature of 60 ° C, with a weight solvent ratio of 1: 5, for 40 minutes proved to be optimal for the maceration of aronia fruits. The total polyphenol content of the optimal extract was determined to be 5237.2 ± 40.7 mgGAEkg-1 and the antioxidant activity by TEAC to be 512.5 ± 5.04 gml-1. 24 aromatic active compounds were identified in the extract, with the largest percentage being monoterpenes and aldehydes. Furthermore, it was found that the extract did not show antimicrobial activity against the microorganisms used (Bacillus cereus, Escherichia coli and Candida glabrata). The obtained results confirm that aronia extracts are an important source of many biologically active compounds and can be used in food as a natural source of nutritionally and sensory valuable substances.
Production and characterization of mead produced by different technologies
Kilian, David ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis is focused on the technology of producing mead from the chosen kind of honey with a variety of sugar concentrations with the use of modern producing technological procedures with the cold and hot process. The theoretical part is focused on the history of mead and its technological development. It focuses, in detail, on modern large scale technologies – both cold and also the hot process. In the practical part of the thesis, the production of samples of mead with various sugar concentrations from three kinds of honey with the use of two technological processes (hot and cold process) was conducted firstly. Secondly, the characteristics of the samples were conducted from the view of the volume of HMF – Hydroxymethylfurfural, ethanol, glucose, fructose, the chosen organic acids and elements with sensory analysis. The prepared samples were compared and discussed concerning differences to find out the differences of the use of the two manufacturing technologies (cold and hot process), the chosen kinds of honey and the influence of sugar before the fermentation on the final product.
Study of the aroma profile of selected varieties of Moravian wines
Gross, Michal ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
The subject of this thesis was the determination of the profile of volatile aromatic compounds of varietal wines and the subsequent statistical analysis, aiming to find varietal markers of selected varieties – individual substances, their typical contents, mutual correlations. The HS-SPME-GC-MS technique was used to determine the aromatic profile. The main focus of this work was the analysis of the varieties Pálava, Hibernal, Johanniter and Solaris. The data obtained were statistically processed using descriptive and multivariate statistical methods. On the basis of these analyses, models were developed which, from the contents of 14 selected compounds of the aromatic profile, allow the Piwi varieties Hibernal, Johanniter and Solaris to be distinguished from each other and from the Pálava variety and, for the Pálava variety wines, to determine their origin in the Znojmo or Mikulov wine sub-region.
Beer bioflavouring by dry hopping using czech cultivars of hops
Gajdušek, Martin ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with the influence of dry hopping on selected analytical and sensory properties of beer. The effect of dry hopping was observed using Czech hop varieties Kazbek and Uran, which were added to the wort during the main fermentation phase in doses of 3 and 6 gdm-3. The contact time of hops with wort was 3, 6 and 9 days. The experimental part describes the technology of preparation of the reference beer, in which dry hopping were subsequently performed. A parallel measurement was performed on each sample. In terms of the basic parameters of beer, the effect of dry hopping, especially its length, on the ethanol content was observed. With a longer period of dry hopping, the concentration of ethanol in beer increased. The higher alcohol concentration was also associated with a decrease in the apparent extract. In terms of color and pH of beer, the effect of dry hopping has not been proven. Elemental analysis performed by optical emission spectrometry with inductively coupled plasma revealed an increase in the concentration of calcium, magnesium, and iron due to dry hopping. No statistically significant difference was observed for manganese and barium compared to the reference. In terms of bitterness, a significant increase was identified in dry hopped beers compared to the reference, the value being dependent on the dose of hops used. The effect of the hop variety has not been proved. Concentrations of organic acids determined by ion-exchange chromatography with a conductivity detector were affected by dry hopping only in the case of lactic acid and acetic acid. An increase in lactic acid was observed compared to the reference, also related to the degree of fermentation. While in the acetic acid content the hop samples showed a lower concentration than the reference sample. The concentrations of myrcene, humulene and geraniol were determined by gas chromatography with a mass detector. These are volatile components of hop essential oils. Dry hopped samples recorded significantly higher concentrations of all aromatic substances compared to the reference. In terms of hop time, the highest concentrations were shown by samples hopped for three days. The results of the sensory analysis show that the overall best rated sample is a sample hopped with the Kazbek variety with a dose of 3 gdm-3 for three days. Beer which was dry hopped for the shortest time also showed the lowest intensity of bitterness, which was perceived positively.
Monitoring of mercury and methylmercury content in fish meat and evaluation of risks associated with the consumption of this meat
Křížová, Lucie ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
Mercury and its compounds are one of the most toxic global pollutants in the environment. It occurs in all segments of the environment, and it attains the food chain ang human body by people consuming fish. The theoretical part of this thesis examines the characteristics of mercury, its occurrence, the roots of its pollution, and the toxicity of various forms of mercury. Consequently, the thesis delineates analytical methodologies applied to determine the overall level of mercury and chemical forms of mercury. The practical part focuses on monitoring the level of mercury and methylmercury in 12 extracts of fish meat. The analyzer AMA 254 has been used to determine the level of mercury and methylmercury in these extracts. Based on the level that resulted from the measurements, the thesis concludes a risk that correlates with consuming this type of meat.
Production and characterization of biochar derived from different kind of bran
Černíková, Eliška ; Kalina, Michal (referee) ; Pořízka, Jaromír (advisor)
The bachelor thesis was focused on production and characterization of biochar prepared from different sorts of bran. According to the philosophy of circular economy bran, the biproduct of flour production, was chosen for the production of biochar. This lignocellulosic material was walked through pyrolysis to broaden potential application. Biochar was prepared by slow pyrolysis and considering its properties multiple applications are possible. Biochar’s usage is limited by European Biochar Certificate. The theoretical part contains general description of biochar properties, requests of European Biochar Certificate and possible analytical methods. In the practical part process of biochar preparation and biochar characterization per chosen methods are described. Analysed properties were: specific surface, pH, particle size distribution, electrical conductivity, composition of elements and content of polycyclic aromatic hydrocarbons. Based on measured data possible applications were recommended. Only biochar from rye bran fulfilled the strict criteria of European Biochar Certificate. However all of the prepared materials can be used in agriculture, except from rice bran biochar which according to EBC can only be used in material industry.
Developement and characterization of protein food supplement from wheat bran
Zhahlou, Kim ; Punčochářová, Lenka (referee) ; Pořízka, Jaromír (advisor)
The bachelor thesis focuses on the development of a new, protein dietary supplement for athletes and followers of a healthy lifestyle. Nowadays, life is more intense the more he gave. From a physiological point of view, a person needs enough energy, which is provided by a varied diet composed of quality nutrients. In the experimental part, protein rods were made with the addition of lyophilized protein isolated from wheat bran. Wheat bran was selected as a suitable source of protein due to its availability, protein content from 14 % to 18 % and the relative simplicity of the protein isolation method. The protein bar thus produced does not contain any ingredient of animal origin, making it suitable for vegetarians and vegans. The textural properties of sticks with different amounts of plant material were compared by sensory analysis. For more illustrative results, the product was also compared with bars made by the same procedure, but with the addition of whey protein. With the addition of wheat lyophilisate over 5%, the negative effect on the evaluation of the textural and taste properties of the sticks was evaluated. Further studies could focus on optimizing the taste and addition of plant protein.
Determination of microelements by ICP-OES after extraction by DGT technique
Habartová, Aneta ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This thesis is focused on determination of microelements (Cd, Co, Cu, Fe, Mn, Ni, Pb a Zn) in milk by optical emission spectrometry with inductively coupled plasma (ICP-OES) after extraction by Diffusion Gradients in Thin films technique (DGT) containing Chelex 100 resin gel and agarose diffusion gel. The optimalization of DGT in model metal solutions was verified by recommended basic tests. The performance of the DGT technique in the diluted milk matrix was verified. By DGT technique was determined only Zn in real milk matrix with concentration 3,74 ± 0,02 mg/l. The other microelements in the prepared eluate were at or below the limit of detection of the instrumental method. The obtained results were compared with the analysis of milk after microwave digestion by ICP-OES. However, these results were below the detection limit of the device too, only Zn with concentration 3,91 ± 0,16 mg/l was measured. For the future analysis of the selected microelements in milk by DGT technique, further optimization of the preconcentration technique is required, or use of a more sensitive instrumental method.

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