|
|
Analysis of active phenolics in some cereal products
Vondráčková, Hedvika ; Vávrová, Milada (referee) ; Márová, Ivana (advisor)
Presented diploma thesis was focused on study of phenolic substances in various cereal products. Flours, brans and germs from various cereals, flakes and extruded cereals were chosen as samples. Phenolic substances were analyzed by spectrophotometry, RP-HPLC/UV-VIS and RP-HPLC/PDA/ESI-MS. Studies of saccharide content which were analyzed by spectrophotometry and HPLC/RI was incorporated to this thesis. Differences in the content of phenolic substances released from glycosides after acid hydrolysis of samples and differences in saccharide content determined after acid and enzymatic hydrolysis of samples were investigated. Simple sensory analysis of extruded cereal products of different flavour (cocoa, honey, chocolate) was carried out too. In analyzed samples the highest content of total phenolics and total flavonoids was measured in wheat germs. Especially in wheat germs and also in buckwheat and oat flakes, maize brans and cereals products Teddy (cereal balls with cocoa) and Ferda (cereal grains with honey) high levels of individual catechins, phenolic acids and flavonoids were determined too. The quantity of phenolic substances increased for several times in samples processed by acid hydrolysis in comparison to non-hydrolyzed samples. The high content of total saccharides, reduced saccharides and individual mono- and disaccharides was found mainly in extruded products. Concentration of monosaccharides increased in acid hydrolyzed samples in spite of disaccharides concentration that was higher only in some of hydrolyzed samples. In several cases final disaccharide concentrations were lower in hydrolyzed samples than in non-hydrolyzed ones.
|
|
|
Amount of selected biologically active compounds in Stevia rebaudiana
Porubčanová, Vladimíra ; Jurečková, Zuzana (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals with plant, called stevia rebaudiana and analysis of phenolic compounds in the extracts from it. The theoretical part describes its botanical characteristics, chemical constitution and effect on humans health. This thesis is interested in sweetener, produced from stevia, comercionally used as E 960: steviol-glykosides, too. There is listed register of companies producing this sweetener and food products, where stevia is used in. The experimental part of thesis is focused to analysis of total phenolic content in stevia extracts, because leaves of stevia are primary used for sweetening of tea. The main aim of the thesis was find out, how is total phenolic content changed during extraction of leaves in time, in water with different temperature and in different samples.
|
|
|
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.
|
|
|
Analysis of juices of selected blackcurrant varieties
Kaniová, Lenka ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
The work deals with the chemical analysis of juices selected varieties of black currant (Ribes nigrum L.). The theoretical part is divided into three main chapters. In the first chapter there are short botanical characteristics of black currants, content of biologically active substances in fruit and utilization of black currant fruit in food industry. In the second chapter there are characteristics, importance and methods of determination of phenolic compounds. Vitamin C is describe in the last chapter, its characteristics, importance and methods of determination. Experimental part describes determination of three chemical characteristic of black currant fruits: content of total phenolic compounds, content of total anthocyanins and content of vitamin C. Twelve modern varieties of black currant were selected for determination. Based on these results, it is possible to deduce the more important varieties. The content of total phenolic compounds was in the range of 326,7–641,4 mg•100 g-1 in all samples. The content of total anthocyanins was analysed in the range from 102,5 to 284,5 mg•100 g-1 in all samples. And content of vitamin C was in the range from 82,0 to 379,1 mg•100 g-1 in all samples. The overall comparison of the varieties of black currant was found, the varieties Ceres, Ben Hope, Ben Lomond, Démon and Ometa are the most promising varieties in terms of the content of the above mentioned compounds.
|
|
|
Chemical and sensory characterization of cider made from apple cultivars ordinarily grown in Czech republic
Strapcová, Zuzana ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This master thesis deals with the investigation of selected chemical and sensory characteristics of ciders, which were made from four selected apple varieties. The theoretical part describes the chemical composition of apples, cider, the technology of production and production in the world. The next section describes the analytical methods used to determine chemical characteristics not only in ciders but also in other alcoholic beverages. The experimental part focuses on the determination of chemical characteristics such as the content of organic acids, carbohydrates, total phenolic content, alcohol antioxidant activity and elemental composition. The purpose of the work was to find out how different varieties differ in chemical composition. The produced ciders were subjected to sensory analysis to evaluate the selected cider sensory parameters, which were in the natural state and with the addition of carbon dioxide. The results show that ciders of different varieties differ in chemical composition. Malic acid was the most cider's abundant of the organic acids in the range of 2759 – 4411 mg·l-1. Another acid represented was lactic acid in the range of 166,2 – 288,1 mg·l-1. The glucose content of each cider was determined between 845,3 – 1159,8 mg·l-1and fructose 32,6 – 406,7 mg·l-1. Potassium 944,29 – 1073,98 mg·l-1 was the most represented of all elements. The total phenolic content was determined to be in the range of 164,2 – 214,1 mg of GAE·l-1and the antioxidant activity of 0,192 – 0,318 mg·l-1. These differences in chemical composition were also reflected in sensory evaluation. According to the overall assessment, the best cider was made from the Granny Smith variety, which contained the most organic acids and carbohydrates. It has been found that by adding carbon dioxide, sensory parameters such as colour, taste and smell are altered.
|
|
|
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.
|
|
|
Analysis of some active substances in different products from rice
Valentová, Radka ; Melounová, Jitka (referee) ; Márová, Ivana (advisor)
Presented diploma thesis is focused on analysis of selected biologically active substances in different kinds of natural and peeled rice. In rice samples phenolic compounds, antioxidant activity, content of saccharides and vitamin C were analysed. Active substances and saccharides were analysed by UV-VIS spectrophotometry and RP-HPLC-UV/VIS. Content of phenolic compounds and saccharides was measured before and after acid hydrolysis. The content of these compounds increased several times because of release of active substances from glycosides. As a part of diploma thesis basic sensory analysis was performed and consumer questionnaires were evaluated. The highest level of antioxidant activity was detected in Indian Wild rice. The highest content of total polyphenols and flavonoids was detected in Red Rice Natural before acid hydrolysis. After acid hydrolysis the highest content was detected in Indian Wild rice. The highest content of individual flavonoids, phenolic acids and catechins was detected in natural rice Indian Wild, Rice Three colours and in two samples of rice parboiled. The highest content of total and reducing saccharides was found in rice Indian Wild before hydrolysis, while after hydrolysis the content was very similar in all rice samples. The amount of individual monosaccharides after acid hydrolysis increased, while total content of disaccharides decreased. The highest value of simple sugars was detected in rice parboiled and Indian Wild rice. The content of vitamin C was detected only in four rice kinds - in two samples of rice parboiled, Rice Three colours and rice Indian Wild.
|
|
|
Possibilities of preparation combined drinks from selected fruits
Zábranská, Miroslava ; Vránová, Dana (referee) ; Vespalcová, Milena (advisor)
This thesis deals with the preparation of the combined alcoholic beverages based on wine and fruit juices. The fruit juices were obtained from the selected fruits as honeysuckle, mulberry, dogwood, rose hips, elderberry, buckthorn and aronia. Some chemical properties e. g. total fenolics, total anthocyanins, vitamin C and sacharides were determined for characterization of the mentioned juices. As well as chemical parameter of juices, the same chemical parameters were determined on wine. There were prepared three sets of combined beverages from wine and juices. The two best evaluated beverages were chosen on the basis of their sensory evaluation. In the end, the same chemical properties were determined in both particular juices and resulting beverages.
|
|
|
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.
|
|
|
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.
|
guest ::
