National Repository of Grey Literature 73 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Use of antioxidants in the production of white sausages
Richterová, Nikola ; Pořízka, Jaromír (referee) ; Mikulíková, Renata (advisor)
This thesis focuses on the use of antioxidants in the production of white sausage. Two herbs were chosen as representatives of natural antioxidants (Salvia officinalis and Rosmarinus officinalis), whose effects were compared with the synthetic antioxidant butylhydroxytoluene. Furthermore, this thesis discusses the possibilities of using the FoodScan 2 device for the determination of basic nutritional characteristics in the produced sausages. The impact of antioxidant addition was evaluated, especially on the sensory quality and consumer acceptability of the manufactured sausage. Herbs were added to the sausages in dried, ground form and in the form of prepared ethanol extracts. The impact on the oxidative damage of the sausages during storage in cold (4 °C) for five days was also examined. The protein, fat, water, and ash content in the sausage samples was determined using the FoodScan 2 device, the results were compared with those acquired using simple analytical methods. On the day of production and then five days of storage in cold, the lipid content and fatty acid profile in the sausage samples were examined by gas chromatography, and the content of substances reactive with thiobarbituric acid in the sausage samples was examined by spectrophotometric analysis. The antioxidant activity of the samples was also measured. Furthermore, the manufactured sausage samples were subjected to microbial control. The prepared ethanol extracts and butylated hydroxytoluene were analysed for antimicrobial activity against Escherichia coli and Micrococcus luteus. For most evaluators, the herbs and their extracts that were added to the meat product appeared tasty and consumer friendly. Statistically significant differences were found between the samples using the Kruskal-Wallis test. In produced samples, herbs exhibit comparable efficiency to synthetic butylhydroxytoluene and could be a suitable alternative to synthetic food additives.
Optimization of the production of yogurt with increased protein content from wheat bran
Adamczyková, Michaela ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This thesis deals with the use of wheat bran in the form of protein isolate as an additive in the food industry, optimalization of the formula of fortified yoghurts and the encapsulation of plant proteins, used as a method to mask the negative sensory properties of products with the addition of these proteins. The theoretical part deals with the characterization of fermented milk products, wheat bran as a source of protein and the possibilities of masking the negative sensory properties of protein isolates. The produced yoghurts were sensory evaluated and their nutritional and technological properties were analyzed in the experimental part. By sensory analysis of yoghurts made from different types of milk, full-fat UHT milk was determined to be the best for the production of fortified yoghurts. Yoghurts prepared from this milk were fortified with wheat bran protein isolate. The products thus had an increased nutritional value, but their sensory values deteriorated. The yoghurts had a gritty feel, which was subsequently mitigated by grinding the protein isolate to finer parts. The formula for the production of fortified yoghurts was optimized by the addition of alternative protein, which had a positive effect especially for yoghurts with a 10% protein content. Yoghurts with protein isolate were evaluated with a negative score for the bitter taste parameter. Encapsulation of proteins significantly reduced the intensity of the bitter taste. Synergy of all prepared samples was determined by filtration. Yoghurt from full-fat UHT milk showed a syneresis of 31.76 ml per 100 g of yoghurt. The addition of protein led to a change in the synergy of this yoghurt. From the rheological analysis, it was determined that 10% yoghurt with encapsulated particles had a higher value of dynamic viscosity and yield stress. Sensory analysis data were evaluated using principal component analysis.
Selection of suitable disinfections to prevent the spread of Corynebacterium pseudotuberculosis in farms focused on the production of milk products and meat
Liová, Alexandra ; Pořízka, Jaromír (referee) ; Marková,, Jiřina (advisor)
This diploma thesis deals with the selection of suitable disinfectants and their effective concentrations for the prevention of the spread of the causative agent of caseous lymphadenitis in sheep and goat farms with a focus on milk processing, dairy and cheese production or meat production. For these purposes, disinfectants were selected from the group of quaternary ammonium compounds, oxidizing compounds, biguanides and alcohols, which were tested according to the ČSN EN 1656 standard on Corynebacterium pseudotuberculosis isolates forming a biofilm. The theoretical part first deals with the general characterization of the bacterial species Corynebacterium pseudotuberculosis and caseous lymphadenitis. In other chapters, the bacterial biofilm, its formation and the factors that influence it are described. Last but not least, the theoretical part is focused not only on the legislative treatment of the use or testing of disinfectants, but also on the closer characterization of their individual groups. In the experimental part, the procedure for determining the sensitivity of Corynebacterium pseudotuberculosis biofilms to selected disinfectants (benzalkonium chloride, chlorhexidine digluconate, ethanol, iodinated povidone, sodium hypochlorite and peracetic acid) was first optimized according to the ČSN EN 1656 standard. The optimization was followed by the cultivation and formation of biofilms of Corynebacterium pseudotuberculosis and the evaluation of their intensity by spectrophotometric determination of optical density. Subsequently, tested disinfectants were applied to the obtained biofilms, and after 24 hours of incubation from the end of the disinfection process, the effectiveness of the tested disinfectants was visually evaluated. At the end of the research, the minimum bactericidal concentrations for individual disinfectants were determined and the concentrations of these substances suitable for preventing and preventing the spread of the bacterium Corynebacterium pseudotuberculosis in small ruminant farms were also selected.
Optimization of fresh cheese production and their characterization
Bittnerová, Eva ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
This thesis deals with the optimization of fresh cheese production and their characterization in terms of free and bound fatty acids, volatile (aromatic) substances and sensory quality. The theoretical part deals with the characterization of fresh cheeses, their production technology and sensory quality. It also includes options for determining volatile substances and fatty acids in fresh cheeses. In the experimental part, produced fresh cheese samples were analyzed during 14-day storage. The fat was extracted from fresh cheeses with a mixture of diethyl ether and petroleum ether, fatty acids were converted to the appropriate methyl esters by acid esterification with boron trifluoride as a catalyst and determined by gas chromatography with a flame ionization detector. Volatile substances were identified based on the comparison of mass spectra with a library of spectra and retention indices (according to Van den Dool and Kratz). The content of the identified substances was expressed semi-quantitatively using the areas of the respective peaks. A total of 20 fatty acids were identified, palmitic, myristic, stearic, capric, caproic and lauric acids predominated as representatives of saturated fatty acids, oleic acid as a representative of monounsaturated fatty acids, and linoleic acid was abundantly represented among polyunsaturated fatty acids. In terms of volatile substances, a total of 37 compounds were identified in the frozen samples and 42 compounds in the fresh samples. Alcohols, acids, aldehydes and ketones were the most represented. The results of the sensory evaluation show that the evaluators liked the stored cheeses better, so the cheeses maintain a good quality of min. for 14 days when stored in the refrigerator.
Development and characterization of new dairy products with increased fiber and protein content
Smatana, Igor ; Punčochářová, Lenka (referee) ; Pořízka, Jaromír (advisor)
The bachelor thesis was focused on the production and characterization of new dairy products with increased protein and fiber content. Ground wheat bran was used as the fiber source and wheat bran protein extract was used as the protein source. From an ecological point of view, it would be ideal if 100% of the raw material was used and nothing was left as waste. We tried to approach this by using the waste (by-product) that arises during the production of flour as an additive to dairy products. The theoretical part focused on the characterization of fermented and unfermented dairy products and their production, the nutritional value of proteins and fiber and the composition and benefits for human health of wheat bran, protein isolation from wheat bran and common analytical methods to determine rheological properties, viable cell numbers. water binding and sensory acceptability. Two basic dairy products were created, one fermented and one unfermented, and subsequently fortified with a source of fiber (wheat bran) and a source of protein (protein concentrate from wheat bran). All products were subsequently characterized for characterization. Water binding, rheological and sensory properties were determined. The fermented dairy product was also subjected to cytometric analysis to determine the number of viable cells. The experimental part describes the methods we use to prepare and characterize new products. After evaluating the measured data, options for optimizing the acceptability of products by consumers were proposed. The results showed that the organoleptic properties were negatively affected by the addition of wheat bran and protein concentrate.
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.
Pretreatment of hops for further processing in beer technology
Tichá, Anna ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with pre-treatment of hops for further processing in beer technology. In the experimental part of the work, the effect of low temperatures, as pre-treatment of hops, on the monitored parameters was observed. Three types of cold pretreatment were used. In two cases, the hop material was frozen using a freezer at -25 ° C and in the second case at -70 ° C. In the third case, the hop material was treated by contact with liquid nitrogen in combination with mechanical treatment. The variety of hop materiál was Žatecký poloraný červeňák, which were in the form of pellets or pressed hop cones. The total bitterness of the samples, the total content of phenolic substances, the total content of flavonoids, the antioxidant activity and the concentration of essential oils, specifically myrcene humulene and geraniol, were examined. The effect of pre-treatment was investigated during conventional worth boiling as well as dryhopping. The experimental part includes descriptions of the hopping process, descriptions of individual analytical methods. A parallel measurement was performed on each sample. Significant advantages or disadvantages of some of the pretreatments were not demonstrable, however, the most significant differences were observed in samples hopped with hops pretreated by freezing at -70 ° C, which had a positive effect on the amount of extracted essential oils during cold hops.
Study of the effect of fertilizer containing wheat bran on lettuce growth
Smrčková, Kamila ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
The aim of the work was to perform growth experiments on a laboratory scale with soil, which was enriched with 2,5 vol. % of wheat bran/coffee grounds/biochar and to study soil and growth characteristics on Lactuca sativa L. The coffee grounds were added raw or modified by oxidation/extraction. Phytotoxic properties of coffee grounds were confirmed by germination tests, although there was an effort to reduce the content of phenolic substances by oxidation /extraction. Soil additives caused an increase in content of organic matter, water capacity, pH and conductivity of all mixtures compared to the control soil. Elemental analysis of soils before cultivation did not show any positive effect on the content of mineral elements compared to the control soil. On the other hand, higher mineral (P, Mg, Ca, K, Mn, Fe, Cu and Al) content compared to soil was recorded cultivation experiments. Chlorophyll a was the most abundant in cultivated plants and reached the lowest concentration in plants grown in a mixture with EXKS. Salads differed in mineral content, too. Salads with the highest content of phosphorus were growed on the mixture BU+OT+PŮDA. On the contrary, content of potassium is salads was negatively affected by mixture with EXKS. Microelements (Fe, Zn, Al, Cu, Cr and Mn) were most affected in the salad by the addition of raw coffee grounds and OXKS2.
Activation of biochar from wheat bran
Sauchanka, Katsiaryna ; Kalina, Michal (referee) ; Pořízka, Jaromír (advisor)
This graduation work is devoted to the issue of biochar production from wheat bran and ways of its surface activation. The theoretical part summarizes information about biochar, its physico-chemical properties, production methods and surface modification options. It also contains description of EBC certificate, that sets requirements for biochar which is placed on the market. The practical part of the work focuses on activating of the biochar surface and comparing the results with the available literature and European biochar certificate.
Quantification of food waste in municipal waste and the possibility of processing this waste
Orságová, Marie ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
The theoretical study of anaerobic digestion is designed to predict the amount of biogas in food waste. The theoretical part characterizes the processing of biodegradable waste as well as the use of biogas and the calculation method for determining biogas production. In the experimental part, the analytical technique of inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine minerals (K, Ca, P, Mg, Na, Zn, Cu, Fe and Mn) in food waste, as well as elemental analysis for carbon, oxygen, hydrogen and nitrogen determination. This thesis provides a simplified model that predicts the amount of produced biogas and could be used for further feasibility studies, such as bioreactors dimensioning. The method can be used for different starting materials and repeated for other similar applications in an effort to extend anaerobic digestion systems as a source of clean energy.

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