National Repository of Grey Literature 32 records found  previous11 - 20nextend  jump to record: Search took 0.01 seconds. 
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.
Stability and properties of combined beverages and fruit concentrates
Klatová, Kamila ; Vítová, Eva (referee) ; Vespalcová, Milena (advisor)
This diploma thesis deals with the stability and basic properties of combined beverages and fruit concentrates. The theoretical part describes the production and use of fruit concentrates. Furthermore, the work deals with anthocyanic pigments and phenolic substances. The principle and instrumentation of liquid chromatography and electron paramagnetic resonance were described. In the next subchapter, the methods of determination of total anthocyanins and phenolic substances were described. The experimental part of the thesis described the determination of soluble solids, viscosity and antioxidant activity. The total content of phenolic compounds were determined by the Folin-Ciocalteua method and the total anthocyanins were determined by the pH-differential method. In the samples were determined cyanidine-3-glucoside and cyanidin-3-galactoside by liquid chromatography.
Properties of plant extracts
Bělonožníková, Kateřina ; Ryšlavá, Helena (advisor) ; Liberda, Jiří (referee)
Plants synthesize a wide variety of compounds called secondary metabolites. These compounds comprise products of the phenylpropanoid pathway (flavonoids, stilbens, anthocyanines and tannins), isoprenoids, and alkaloids. Since plant secondary metabolites seem to affect human health in a positive way, decrease the risk of some diseases such as cancer, diabetes type 2 and disorders of the cardiovascular system, their studies attract a lot of attention. The mechanism of the effect of individual compounds on human health has not been clarified yet, the positive effect is probably caused by their antioxidant capacity. In this work 22 extracts from different kinds of fruit and vegetables were prepared. The total content of phenolic compounds and flavonoids, the antioxidant capacity by methods FRAP (ferric ion reducing antioxidant power) and ABTS [2,2'-azino-bis(3-ethylbenzthiazoline-6- sulphonic acid)] were determined. High content of phenolic compounds was established in the extract from strawberry, cherry and kiwi, the highest antioxidant capacity was found in the extract from strawberry. Another studied attribute of extracts from fruit and vegetables was their influence on the activity of digestive enzymes pancreatic lipase and α-amylase. The extracts from lemon, red currant, jostaberry, lime and...
Biochemical changes accompanying the aging of red wine
Vacková, Tereza ; Hudeček, Jiří (advisor) ; Entlicher, Gustav (referee)
Flavonoids are plant secondary metabolites, which belong to several groups varying in their chemical structure. Anthocyanins and tannins are important flavonoid components of wine that are responsible for its color, taste and other sensory properties. The concentration of anthocyanins in wine is affected by grape variety, processing technology, and climatic conditions. In this Thesis, we studied the changes in color and in related chemical composition, using three non-commercial samples of red wine: Svatovavřinecké (year 2010 and 2012), and home-made wine (prepared without addition of SO2). These changes in color were determined using standard colorimetric method (CIELab) and also a simplified two-parametric spectrophotometric method (tint/color density). The content of anthocyanins was followed using analytical RP-HPLC method. In paralel, simplified oenologic methods for estimation of phenolic compounds were used. Generally the wine samples changed color to darker tint. Chemically, this was caused by polymerisation reactions between anthocyanins and phenolic compounds. This led to the formation of stable pigments characterised by a higher absorption maximum at longetr wavelength, hence a darker tint. Key words: anthocyanins, color, red wine, phenolic compounds, malvidin-3-glucosid, polymeric reactions,...
Analytical methods for verifying the authenticity of the wine
Flegr, Šimon ; Štursa, Václav (referee) ; Diviš, Pavel (advisor)
This bachelor’s thesis deals with the authenticity of wine, focusing on the authenticity of geographic origin. The theoretical part of this work summarises the main components of wine and their changes during the production proces. Control techniques are introduced, including the ones used by the goverment’s control bureau (SZPI) and other documented methods. Areas recognised for growing wine are described, including the Morava area in Czechia and its imminent adjacent areas in Austria and Slovakia. Experimental part deals with the trace amount analysis of selected elements and phenolic compounds. The element analysis was conducted using mass spectrometry and optical emission spectrometry, whilst the phenolic compounds were separated using high-pressure liquid chromatography with spectrophotometric detection. The results were analysed using discrimination analysis to separate groups with different areas of origin, with the aid of data from former research.
Developement and optimalization of methods for extraction of selected compounds from Hypericum perforatum
Chytil, Dalibor ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
Bachelor's thesis deals with the optimization of processes for extraction of phenolic compounds from St. John´s Wort (Hypericum perforatum). The theoretical part of the work focuses on characterization of this herb, its botanical classification, traditional use, chemical composition and curative effects. Increased attention is further devoted to a theory of preparation of samples for extraction of phenolic compounds and suitable techniques for extraction and characterization of phenolic compounds from extracts of St. John´s Wort. The experimental part of the thesis deals with application of theoretical knowledge. When optimizing the emphasis was on influence of solvent (water acified to pH 4, pH 5, pH 6), influence of extraction technique (ultrasound extraction, subcritical water extraction, maceration) and influence of extraction period (10, 20, 30 min). Extracts were subjected to determination of selected parameters (total phenolic content, total flavonoid content, antioxidant activity) in leaves of St John´s Wort harvested in June 2016 using UV-VIS spectroscopy. The used extraction techniques are significantly different from each other.
Study of penetration of selected substances from elderberry extracts through biological membrane
Škubalová, Zuzana ; Němcová, Andrea (referee) ; Vespalcová, Milena (advisor)
This Diploma thesis focuses on the study of penetration of selected phenolic substances contained in extract from black elder (Sambucus nigra) via modelling systems represented by two types of synthetic membranes and a real system represented by a biological membrane. As a biological membrane, we have chosen skin from pig´s earlobe. Experiments of transdermal absorption and absorption through synthetic membranes were conducted through vertical (Franz´s) cells. Selected substances contained in the extract from black elder were rutin and chlorogenic acid. The main focus of this work was to determine how readily, or if at all, these two selected phenolic substances penetrate the skin and selected synthetic membranes. The percentage of absorbed amount of the substance was determined by HPLC analysis.
NADP-dehydrogenases of medicinal plants.
Bartošová, Martina ; Hýsková, Veronika (advisor) ; Kubíčková, Božena (referee)
Medicinal plants usually contain metabolites formed by secondary biosynthetic pathways for example phenylpropanoid and shikimate pathway, which depend on NAPDH availability. In this work total content of phenolic compounds and flavonoids was determined in 10 medicinal plants common for Czech Republic. Activity of enzymes providing NADPH was determined as well. These enzymes were glucose-6-phosphate dehydrogenase (G6PDH, EC, NADP-isocitrate dehydrogenase (NADP-ICDH, EC, NADP-malic enzyme (oxalacetate decarboxylating) (NADP-ME, EC The activity of shikimate dehydrogenase (SDH, EC, the main enzyme of shikimate pathway, was also determined. Extraction methods were optimized for each assessment. Applicable source for NADP-dependent enzymes are black radish (Raphanus sativus L. var. niger), garlic (Allium sativum L.) and mint (Mentha piperita L). The highest content of phenolic compounds and flavonoids was determined in sage (Salvia officinalis), lemon balm (Melissa officinalis L.) and Mentha citrata. Extraction with methanol was more effective than extraction with hot water. More extraction methods and studies are necessary for characterization of individual compounds and principals on which they work. Key words: medicinal plants, NADP-dependent enzymes, phenolic...
Evaluation of the influence of the pasterization and filtration on selected chemical components of beer
Vopelková, Dominika ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
The aim of this work was to study the influence of the pasteurization and filtration on selected chemical compounds in beer. Specifically, the influence on elemental composition, content of organic acids, carbohydrates and phenolic substances was studied. Optical emission spectrometry with inductively coupled plasma (ICP-OES) was used for elemental analysis of beer. Analysis of organic acids was evaluated by Ion chromatography. For analysis of carbohydrates was used High performance liquid chromatography with ELSD detector (HPLC-ELSD), phenolic compounds was evaluated by HPLC with diode array detector (HPLC-DAD). Data from analysis of beer was performed by usage of statistical methods (analysis of variance and principal component analysis). Parameters that showed the most significant differences between individual groups of beers were obtained. Correlations between the variables and the technological beer processing operations were found. 12 parameters of total 23 were affected. The effect of filtration and pasteurization was observed in content of the iron, silicon, potassium and magnesium, malate, monosaccharides glucose and fructose and phenolic compounds.

National Repository of Grey Literature : 32 records found   previous11 - 20nextend  jump to record:
Interested in being notified about new results for this query?
Subscribe to the RSS feed.