National Repository of Grey Literature 155 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Aromatisation of wine by different types of wood
Hrošíková, Monika ; Slavíková, Zuzana (referee) ; Pořízka, Jaromír (advisor)
This thesis deals with aromatised red wines using different woods as an alternative method of colouring. It focuses on the phenolic profile of the wine, more specifically on the substances extracted from the wood into the wine, the organic acids and the overall sensory character of the wines aged in contact with the wood. The theoretical part describes the technology of red wine production, its chemical composition, the method of colouring and its alternatives and the associated treatment and modification of the chemical composition of the wood. It also focuses on the phenolic substances extracted and the changes in the sensory profile during the ageing of wine in contact with wood and the possibilities of determining the chemical and sensory profile of these aromatised wines. The experimental part focuses on the chemical and sensory analysis of the changes of a reference Merlot wine during ageing with different types of wood in a two-week and two-month maceration. Changes in the concentrations of total phenolic compounds by Folin-Ciocalteu method, organic acids by ion chromatography, selected phenolic compounds by LCxMS, furfural compounds by GC-FID and colour parameters were monitored.
Analysis of functional properties of protein isolates
Vojtasová, Tereza ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
Proteins are an important part of the human diet, and a lack of them can lead to many health problems. Therefore, they are often added to enrich foods. For food applications, it is desirable to know the functional properties of the proteins used, as they can significantly affect the resulting quality of the final product. This bachelor thesis was focused on the determination of functional properties of some commercially available protein powders: pea, beef, hemp, rice, egg, soy, whey, and laboratory-prepared wheat bran protein powder, and their possible application in food industry. The theoretical part of the thesis described proteins, their functional properties, production, quality assessment, then plant and animal proteins and methods of characterization of protein isolates and concentrates. In the experimental part, individual determinations of functional properties were performed and their applications in food industry were discussed. The solubility of tested protein powders was variable, with the highest solubility observed in powders of animal origin. The lowest solubility was found at pH 3–5, where the isoelectric point of most proteins was located. Soy protein isolate showed the best water-holding capacity of 10.65 gH2O/g, foaming capacity of 109.6% and emulsion properties. It was followed by pea protein with a WHC of 5.32 gH2O/g. Wheat bran concentrate had the best oil holding capacity of 2.18 goil/g. Foaming properties varied considerably but showed a positive correlation with water-holding capacity. The emulsion activity was very similar for most of the protein powders, except for beef, hemp and rice protein which exhibited no good functional properties. Only the beef hydrolyzed collagen was fully soluble. The emulsion layer increased slightly after heat treatment for the proteins, which already formed quite stable emulsions, except for wheat bran powder. Hemp and bran protein powders were the most distinctive in color, while egg and beef protein powders were the lightest. Soy and pea protein isolates showed foaming and emulsion properties similar to egg white proteins, indicating their potential use as partial or total replacements for egg white proteins in food products. In conclusion, selecting protein isolates with suitable functional and sensory properties for a specific food application is crucial for successful consumer acceptance of the protein-enriched product.
Monitoring of nutritionally imporatnt elements and inorganic contaminants in moravian red wines
Dukát, Dominik ; Trenzová, Kristina (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the monitoring of selected elements, mainly toxic and nutritionally important macro- and microelements, in Moravian red wines. The aim of this work was to compare the elemental composition between biovines and wines from other production systems and also to compare wines from four Moravian sub-regions. For these analyses, two analytical methods were chosen: inductively coupled plasma mass spectrometry (ICP-MS) for the determination of microelements and inductively coupled plasma optical emission spectrometry (ICP-OES) for the determination of macroelement concentrations. ANOVA (analysis of variance) test was used for further evaluation. Nickel, magnesium and potassium were identified as statistically significant elements.
Study of the spent coffee grounds addition on the physico-chemical properties of the soil
Kavková, Kateřina ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
The aim of this thesis was to conduct a growth experiment of lettuce and corn in soil mixtures containing 2.5% modified (oxidized coffee grounds, defatted coffee grounds, oxidized defatted coffee grounds) or raw coffee grounds and compared these plants to plants that grew in clean soil without treatment. Both growth characteristics and chemical analyzes were studied - elemental analysis, amount of chlorophyll, etc. In germination tests, the effect of coffee grounds toxicity on seeds was demonstrated, except for the mixture with defatted grounds, when the maize seeds did so well in the leachate that they had sprouted leaves as in the mixture alone. The soil after the cultivation of lettuce and after the cultivation of maize was also analyzed and their values were compared with the soil before cultivation. Changes in pH, elemental composition, content of phenolic substances or content of organic matter were monitored.
Developement and characterization of high protein plant-based yogurt
Smatana, Igor ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
The thesis was focused on the production and characterization of plant-based yogurts with increased protein content. The aim was to design and optimize the formula of new plant-based products. The motivation for this work was the ever-increasing demand for plant-based food alternatives in recent years. The theoretical part was focused on the trend of development of dairy alternatives as well as the nutritional challenges associated with modern diets such as vegetarianism and veganism. Focus was also on the nutritional importance of protein and the composition of proteins of plant origin. The impact of live bacteria on human health, as well as common analytical methods for determining rheological and sensory properties was also included. In the experimental part, the methods used for the preparation and characterization of novel plant-based high-protein yogurts were described. The results showed that the biggest challenge in the production of plant-based yogurts, without added stabilizing agents, is to achieve an acceptable texture, so that the products are neither too watery nor too tough, while maintaining suitable sensory properties. For the products with the addition of 20 g of almond protein, this texture was almost achieved, while maintaining the appropriate sensory characteristics. In contrast, for products containing 10 g almond protein and 6 g of pea or rice protein, the texture was unacceptable and the products were splitting into 2 phases.
Study of adsorption of organic pollutants on wheat bran biochar
Hanák, Jan ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This diploma thesis explores the application of the Diffusive Gradients in Thin Films (DGT) method for determining and monitoring the concentrations of dissolved pharmaceuticals and organic dyes in water and food. The theoretical part introduces the issue of the occurrence of these organic substances in water and food, the principles of the DGT method, the characteristics of adsorption and adsorption isotherms, and the introduction of biochar as an adsorbent. The experimental section primarily focuses on optimizing and validating adsorption gels containing commercial biochar and unmodified biochar from wheat bran for the adsorption of specific substances using the DGT method. Oxytetracycline was primarily tested from a selection of antibiotics and malachite green from organic dyes, which is widely used in aquaristics. The results demonstrate a comparison of the effectiveness of adsorption using these two types of adsorbents and their characteristics, such as infrared spectroscopy analysis or images from a scanning electron microscope. From the Langmuir isotherm, the maximum adsorption capacity for oxytetracycline on commercial biochar was found to be 314,065 mgg-1 and the maximum adsorption capacity for wheat bran biochar was 89,720 mgg-1. The maximum adsorption capacity of commercial biochar for malachite green was 439,406 mgg-1. The work further emphasizes the potential of the DGT method as a tool for food analysis and investigating contaminants in water systems, which further move into the food chain.
Jelly candies with the addition of bilberry (Vaccinium myrtillus) extract
Knapovská, Pavlína ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
This thesis deals with the application of bilberry fruits (Vaccinium myrtillus) and their extract to jelly candies and the subsequent characterization of these candies in terms of volatile compounds, total phenolic compounds and anthocyanins, antioxidant activity and sensory quality. The volatiles were determined by headspace solid-phase microextraction coupled to gas chromatography with mass spectrometry and standard spectrophotometric methods were used for the determination of bioactive compounds. Total phenolic content was determined by the Folin-Ciocalteu method, antioxidant activity by the TEAC method and total anthocyanin content by pH differential analysis. The sensory quality of the samples was evaluated using unstructured graphical scales. The preparation of the bilberry extract was optimized on the basis of total phenolic content and the following conditions were selected as the optimal: a weight of 1000 grams of bilberries per litre of water, a temperature of 50 °C, and an extraction time of 2 hours. The optimum additions to candies were selected, by sensory analysis, as 25 wt. % of extract and 15 wt. % of bilberries. A total of 45 volatile compounds were identified in the candy with bilberry extract, the most abundant being (E)-9-hexadecen-1-ol (22,7 %), furfural (10,9 %) and 2-ethylhexan-1-ol (10,0 %). The total phenolic content was 1141 ± 11 gGAE · g-1, the antioxidant activity was 660 ± 66 gTE · g-1 and the total anthocyanin content was 418 ± 23 gC3G · g-1. A total of 40 volatile compounds were identified in the candy with bilberry and the most abundant were linalool (22,7 %), (E)-9-hexadecene-1-ol (16,1 %) and 2-ethylhexan-1-ol (8,4 %). The total phenolic content was 1735 ± 56 gGAE · g-1, the antioxidant activity was 1109 ± 32 gTE · g-1 and the total anthocyanin content was 745 ± 23 gC3G · g-1. With the addition of both the extract and the bilberries, the candies showed a significant increase in bioactive and volatile compounds content, and the colour and flavour of the enriched samples were positively evaluated, thus improving their overall acceptability.
Study of physio-chemical properties of high-protein baking mixtures
Damborská, Alexandra ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
In terms of nutrition, proteins are an integral part of the diet. They have many functions in the human body, and their lack in the diet has a negative effect on human health. For now, the biggest source of protein is animal production. However, plant sources, which are also rich in protein content, are also starting to come to the fore. Pastries are among the most consumed foods in the world. By adding protein isolates, concentrates or hydrolyzates, you can increase the protein content of baked goods and, in addition, enrich its amino acid profile. The following proteins were selected for the preparation of high-protein bakery mixes - pea protein isolate, wheat bran protein concentrate, beef protein hydrolyzate, brown rice protein isolate, egg white protein isolate, whey protein isolate, soy protein isolate, gluten and hemp protein concentrate. The protein content of plain wheat flour was determined to be 11%. The mixtures were mixed so that the resulting protein content was 20%. The reference sample of plain wheat flour T530 and the high-protein mixture were analyzed to determine the chemical and mainly the rheological properties. From the rheological determinations, a farinographic and extensographic analysis of the formed doughs was performed. The determined parameters were processed by the principal component analysis method to compare the properties against the reference.
Study of the quality of oilseeds in bread products
Fučík, Jiří ; Pořízka, Jaromír (referee) ; Vespalcová, Milena (advisor)
This bachelors thesis focuses on analysis of crude oils pressed from oil seeds commonly used in bread products. Analysis of oils is made on different heat treated samples of seeds and commercial available oils. In the theoretical part is described the bread-making technological steps and processes, characterized oil seeds used in bread-making and oils from these seeds. In addition there is a description of experimental techniques and used types of quantitative analysis: saponification number, acidic number, ester number, iodine number and peroxide number. In the experimental part was analysed in total three samples of commercial available oils (flaxseed, sesame, sunflower) and three samples of oils pressed from fresh oil seeds (flaxseed, sesame, sunflower). Seeds were also baked in the bread, pressed and analysed. Results of each sample preparation phase was compared and possible change justified.
Influence of beer protein on foam stability
Benda, David ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the influence of beer proteins, phenolic compounds, bitterness and selected metal ions on beer foam stability. The theoretical part describes beer foam from the physical aspect, beer foam stability and its measurement and the factors that positively or negatively influences the stability and quality of the beer foam. In the theoretical part are described selected proteins that influence beer foam. In theoretical part is described the origin and technological significance of proteins. The experimental part is dedicated to the measurement of beer foam stability with the NIBEM method, the analysis of total protein content, the analysis of total phenolic content, bitternes and element analysis of beer samples. Measured data indicated correlations between protein content, phenolic compounds content, bitterness and metal ions with the beer foam stability. The results show that proteins and phenolic compounds as isolated parameters don’t essentialy affect the beer foam stability. It was found out, that bitterness as isolated parameter influences the beer foam stability the most.

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