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Chemical composition of wine produced from PIWI cultivars
Michálková, Kateřina ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deasl with the chemical charakterization of wine from selected PIWI varieties. The theoretical part describes the general origin and reason for breeding PIWI varieties, a closer characterization of selected three PIWI varieties, Johaniter, Hibernal and Solaris. The next part is devoted to the description of analytical methods that were used to determine the chemical characteristics. The experimental part is developed to the determination of chemical characteristics, namely general characteristics such as alcohol, total phenols, phenolic substances, volatile substances and elemental composition. The results show that are differences between wines from selected PIWI varieties in therms of chemical composition. The most represented organic acid was in the range of 735,1-1286,2mg/l malic acid. This was followed by acetic in the range of 100-400mg/l. The antioxidant activity was determined in the range of 0,2988-0,9683 mmol/l of Trollox and content of total phenols 273,5-390,3mg/l. Of the phenolic substances, gallic acid was the most represented, ranging from 6,9-13,9mg/l. As another, abundant phenolic substances, catechin in the range of 1,6-6,0mg/l was detected. Of the determined elements, phosphorus in the range of 165,4-450,5mg/l was the most represented. Representatives of ethyl ester, ethyl acetate, decanoic acid ethyl acetate and hexanoic acid ethyl ester, were detected as the most abundant volatiles. From the measured data it was evident that wines from PIWI varieties different from standard varieties, especially in the profile of aromatic substances.
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Study of the antioxidative potential of selected fruit marcs
Havlíčková, Barbora ; Zemanová, Jana (referee) ; Vespalcová, Milena (advisor)
Subject of this bachelor thesis was antioxidant activity of selected kind of fruits. Among selected kinds were the marc of red and white grapes, moldings from red elderberry and aronia. Two species of made capsules from marcs of white grapes and aronia were also subjected to analysis. Results of this bachelor thesis are summarized to four chapters. The first chapter compares the water content of drying at 40 ° C and 105 ° C. In the second chapter, the results of extraction in different proportions of solvent mixture ethanol - water and results of extraction in prepared artificial gastric juice are discussed. As a result, the water – ethanol mixture was a more effective solvent than artificial gastric juice. The third chapter deals with the results and discussion of the determination of the total content of phenolic substances. For the solvent mixture, the largest amount of polyphenols in the red vine marc was determined to be 43,56 mg.g-1, while in gastric juice the largest content in the elderberry was determined to be 11,89 mg.g-1. Capsules were also extracted in gastric juice, and 2,53 mg.g-1 was found in aronia tablets, while 5,93 mg.g-1 in white grape tablets. The last chapter compares the results of TAA measurements using the TEAC and EPR methods. The EPR method was more suitable for much diluted solutions than the TEAC method. The results of this work show that there is a large number of polyphenols and other antioxidants in the moldings that affect the overall antioxidant activity. Marcs have great potential for use as natural dyes or can be used to make a food supplement.
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Analysis of active substances contained in lavender and thyme extracts
Vašíčková, Milada ; Vysoká, Marie (referee) ; Skoumalová, Petra (advisor)
The presented bachelor thesis is focued on active substances contained in lavandula officinalis and common thyme extracts, mainly their possible antimicrobial and antioxidant effects. The theoretical part desrcibes chosen plants, compounds with antimicrobial and antioxidant effects, methods how to obtain and identify said compounds. In the experimental part, aquenous, ethanolic and oil extracts were prepared. Mentioned extracts were spectrophotometrically characterised for total content of polyphenols, total content of flavonoids and antioxidant activity. In conclusion possible applications of extracts in food industry instead of synthetic preservatives and their fotification were discussed.
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Study of natural substances of ginger
Dobiáš, Vojtěch ; Vespalcová, Milena (referee) ; Veselá, Mária (advisor)
The aim of this study was to determine the quantity of natural substances in ginger. Extracts from organic ginger tea and ginger rhizome were prepared using three different solvents. Antioxidant activity and the content of polyphenols and flavonoids were determined spectrophotometrically. Effects on bacterial growth of the extracts were studied against bacteria Bacillus cereus and Serratia marcescens by agar well diffusion assay. The obtained data showed, that there is a significant amount of difference between the contents of studied compounds in the two extract samples. The highest amount of polyphenols was found in ginger tea with concentration of 0,481 mgml-1, compared to 0,078 mgml-1 found in the ginger rhizome. The tea showed a greater antioxidant activity than the rhizome. Bacterial growth was slightly inhibited only by water extracts of the tea and this was only observed against Bacillus cereus.
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Characterization of edible films with the potential usage in food packaging
Jančíková, Simona ; Vítová, Eva (referee) ; Veselá, Mária (advisor)
In the last years, the edible packaging has been gaining popularity due to the potential usage as the packaging for food instead of synthetic materials. The edible packaging can positively affect the packaged food by the active properties or due to its intelligent properties can monitor the changes in food. In theory, the legislation about the packaging of food and edible packaging was described. The substances for edible films preparation and additives, which can improve the properties of the edible films, were described too. In this part, the undesirable microorganisms occur in food and the chapters about active and intelligent properties of the edible films were summarized. The main aim of the thesis was the practical preparation of edible packaging/films made from furcellaran, gelatin hydrolysate with the addition of water dried or fresh rosemary extracts in concentrations 5 %, 10 %, and 20 %. In the experimental part, the physical analysis was done – textural parameters such as tensile strength and elongation at break, water content, and thickness. In the chemical analysis the total polyphenols content, determination of polyphenols by HPLC, antioxidant activity, optical properties and antimicrobial activity of the prepared edible films were done. There were found out, that the total polyphenols content and antioxidant activity were the highest in the 20%DR (TPC: 6,79 ± 0,06 mg gallic acid/g; DPPH: 87,84 ± 0,07 %). Also, the 20%DR and 20%FR changed color in different pH (3 and 12). The antimicrobial activity was negative. The thesis showed that the addition of natural extracts to edible films can increase the polyphenols content and they can also work as the UV protector.
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Comparison of the properties of chokeberry spreads of different origins, comparison and different production technologies
Kapiton, Ulyana ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
This diploma thesis deals with comparison of the properties of chokeberry spreads of different origins, composition and different production technologies. The theoretical part contains a brief description of the chokeberry – Aronia melanocarpa, an overview of the most important substances contained in the chokeberry and examples of the use of aronia, not only in the food industry. Furthermore, the legislative requirements for the production of spreads and the production technology itself are described. In this thesis is also described a new patented technology of spread production using HTD technology. Another part of the theoretical part is a literature review of the determination of anthocyanins in chokeberry by HPLC method. The experimental part describes the laboratory procedures used for determination of dry matter, carbohydrates by HPLC with ELSD detector, anthocyanin dyes, total phenolic compounds and antioxidant activity. Another part of the work was a questionnaire survey and sensory analysis of selected chokeberry spreads. The panel members prefered the Lowicz chokeberry spread, for which was determined 29,39% dry matter, 15,15 mg.g-1 anthocyanins, 9,20 mg.g-1 total phenolic compounds, 158,42 mg.g-1 fructose and 151,26 mg.g-1 glucose and the antioxidant activity was determined to be 5,94 mg.g-1.
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Uses of active compounds from honey in cosmetic products
Balášová, Patricie ; Langová, Denisa (referee) ; Skoumalová, Petra (advisor)
The bachelor thesis was focused on the preparation and characterization of extracts and liposomes with active substances from chosen types of honey with the aim to apply these extracts to the cosmetic products. The extraction of active substances from chosen material was optimized during the work. As the most suitable organic solvent for extraction was chosen diethyl ether. All the extracts were tested on the content of total polyphenols, sugars and antioxidation activity. The final samples were also tested on the content of flavonoids. Extracts were encapsulated to the liposomes, which were tested especially for their antioxidation activity, size and stability. Then, extracts and liposome particles were applied to the cosmetic products. Cosmetic creams and gels were prepared and tested for antioxidation activity and antimicrobial activity against the strains Serattia marcescens and Micrococcus luteus. Antimicrobial activity of gels was proved especially against the strain of grampositive bacterias – Micrococcus luteus. From this point of view another one testing strain was chosen – Propionibacterium acnes. Finally, the chosen liposomes were tested for their contact with human cells, immortalized keratinocytes HaCat. No cytotoxic effect was observed and tested materials can be applied to cosmetics against acne.
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Evaluation of modifications in content of selected bioactive substances in flax (\kur{Linum usitatissimum} L.) seeds during germination
HAŠKOVÁ, Kateřina
This thesis focus on analysing effect of germination on some groups of bioactive compounds in flaxseed. We used flaxseed variety named Libra. Its germination was 10 days long, done in two different conditions: in the dark and fully iluminated for 24 hours daily. Samples were taken on 2nd, 4th, 6th, 8th and 10th day. Following analyses were performed: determination of dry matter content, lipid content, content of nitrogenous compounds, content of proteins and protein spectrum, chlorophyll content, content of total polyphenolic compounds and antioxidant activity. Content of dry mater was proved to decrease during germination as well as lipid content regardless of light conditions. Amount of nitrogenous compounds stayed relatively unchanged during germination. Whereas amount of proteins increased depending on duration of germination and light conditions. Hydrolysis of proteins during germination was proved by protein spectrum analysis. Content of chlorophyll inreased in light-germinated seeds only. Increasing effect of germination on total polyphenolic compounds content and antioxidant activity was proven as well. Moreover aproximately two-fold rise of values was reported after defatting of samples.
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Complex characterisation of medical herbs and study of their utilization in food industry as a source of functional components
Burdějová, Lenka ; Kráčmar, Stanislav (referee) ; Šilhár, Stanislav (referee) ; Polovka, Martin (advisor)
Presented thesis deals with the complex characterization of extracts from medical plants using spectroscopic and chromatographic techniques, with emphasis on the influence of solvent, post-harvest treatment of the sample, location and year of production on selected parameters. Part of the work is devoted to application of selected extracts from medical plants in suitable form into beverages. The thesis is divided into two parts. At the first part of the work combination of electron paramagnetic resonance, ultraviolet visible spectroscopy, liquid chromatography and inductively coupled plasma optical emission spectrometry was applied for characterization of aqueous, ethanol and dimethylsulfoxide extracts from 10 selected medical plants, which were collected from two different locations during two years (2015, 2016) and post-harvestly treated by two ways (freezing, drying). In total, 39 parameters were determinated: namely total phenolic compounds content, total flavonoids content, 14 specific phenolic compounds, colour characteristics in the CIE L*a*b* system (L *, a*, b *, C*, h°, BI), radical-quenching activity using the cation radical of the 2,2'-azino-bis- (3-ethylbenzothiazoline-6-sulfonic acid), antioxidant/pro-oxidant activity using the spin trapping technique in the presence of 5,5-dimethyl-1-pyrrolin-N-oxide (DMPO)/potassium peroxodisulphate and content of 15 minerals (Al, As, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, Zn). The results confirmed that the studied parameters of medical plants are influenced by the extraction system, post-harvest treatment of samples, year of production, origin of samples (locality) and species composition. It has been shown that the type of extraction solvent significantly affects the composition of the extracts. On the basis of these analyzes, for food application – the isolation of the main functional components (phenolic compounds, flavonoids) –50% ethanol, post harvest treatment by drying and samples of Mentha piperita, Melissa officinalis, Hypericum perforatum and Salvia officinalis were selected. The second part of the thesis was focused on the application of selected extracts of medical plants to beverages (syrups). The above mentioned plants, 25% ethanol instead of 50% ethanol (due to the limitation of the ethanol content in final raw material), were selected for the application. At first, extraction of medical plants was optimized. Suitable ratio of material and solvent (1:10), extraction time (8 h) and herb absorbency (50–62 %) were determined. The prepared extract after filtration was applied to the syrup concentrate in different ratios to produce one-species syrups and further sensorially tested to select the suitable recipe, the best flavour and basis for the production of two-species syrups. The mint syrup was the most tasty and generally the most acceptable one-species syrup, and sage syrup was selected as the basis for two-species syrups. Further, the most appropriate recipes of the two-species syrups were chosen, the most sensorially acceptable one was selected and further tested if it would be appropriate to colour them. Preferentially, it has been found that it is not necessary to colour two-species syrups. On the basis of the sensory analysis, it has been found that peppermint and sage-peppermint syrups were the most tasty and acceptable syrups, which could be, after further testing, produced industrially to enrich the food market.
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Antioxidant activity of green tea extracts
Šedý, Michal ; Vítová, Eva (referee) ; Veselá, Mária (advisor)
This bachelor thesis focuses on antioxidant and biological active compounds present in green tea extracts. Green tea is a rich source of antioxidants and it has been considered a medicinal beverage in the past. Series of compounds contained in green tea extracts exhibits strong antioxidant effects. The theoretical part of this thesis deals with the history and production process of tea. It also focuses on the description of the most abundant antioxidant and bioactive substances in tea. Three green tea samples from the retail chain were selected in the experimental section, which were further analysed by selected UV-VIS spectrometry methods and then compared.
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