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Determination of total antioxidation activity of tea pickles in selected sorts of tea
Bartošová, Jitka ; Vitoulová, Eva (referee) ; RNDr.Jana Skopalová, Ph.D. (advisor)
This thesis deals with the total antioxidant activity (TAA) evaluation of various sorts of tea (green, black, half-fermented, white, mate, rooibos and herbal) depending on the process and time of their treatment. The main emphasis is put on testing a new method of measuring the total antioxidant activity by flow coulometry. The results acquired by this method are compared to the results of the chemiluminescent Trolox equivalent antioxidant capacity (TEAC) method which is a standard for measuring the total antioxidant capacity in various materials and raw materials. The work discusses the reasons for the differences in the values found by both methods.
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Analysis of active substances in instant beverages for child´s nutrition
Jašková, Martina ; Kočí, Radka (referee) ; Márová, Ivana (advisor)
The aim of presented diploma thesis was to characterize baby beverages for early infant feeding. Theoretical part deals with baby foods and beverages including breast milk. Practical part is focused on analysis of active substances in 21 commercially available fruit and herbal instant granular baby beverages and in 3 packaged tea bags for infant and toddler age. To evaluation of antioxidant properties some group parameters were used - total polyphenols, total flavonoids, total antioxidant activity and anthocyanins. All of them were analysed by using spectrophotometrical methods. For identification and quantification of individual phenolic substances was used RP-HPLC/UV-VIS and HPLC/PDA/LC-MS, identification of individual mono- and disaccharides was performed by HPLC/RI. L-ascorbic acid supplemented to some children's drinks was analysed by HPLC-NH2/UV. Protein analysis was performed by Experion microfluidic electrophoresis system (BioRad) and protein concentration was verified by colorimetric method. In general, the highest content of phenolic compounds was shown in tea bags when compared with instant granular beverages that contain mostly added simple carbohydrates. Using contact microbial tests proved immediately after opening and also during manipulation with tea boxes was verified that analysed baby teas are in agreement with strict hygiene requirements for baby beverages.
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Elemental analysis of selected types of herbal teas
Adámková, Petra ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
In this bachelor thesis the concentrations of magnesium, potassium, manganese, zinc, copper, chromium, cadmium and lead in selected herbal teas and their infusions were determined. Teas from two competing producers on the Czech pharmaceutical market were selected for analysis. The aim of this work was a mutual comparison of selected tea samples in terms of their elemental content. An indicative study of the effect of water temperature and leaching time on the release of elements into the solution during the preparation of the pickle was carried out. The applied method included the decomposition of samples in a microwave device in the presence of concentrated nitric acid and analysis of the composition of the prepared solutions using ICP-MS. The results showed that the element contents differ according to the type of plant and according to the producer. Furthermore, it was proven that the leaching time has a greater influence on the release of elements into the solution than the water temperature. In this work, it was also verified that the ICP-MS method was suitable for determining the concentrations of all selected metals due to low detection limits. Key words Mass spectrometry, inductively coupled plasma, herbal teas, metals, microwave decomposition
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Bylinné čaje a jejich antioxidanty
Ilčíková, Ladislava
In its first part, this Bachelor thesis named Herbal Teas and Their Antioxidants defines the term free radical and oxidative stress. Firstly, it discusses antioxidants which are presented in vegetal materials. It divides them into categories pursuant to their origin and their structure, and to other significant antioxidants and it researches their medicinal properties in relation to various groups of diseases, Secondly, it explains the consequences of excessive intake of antioxidants. The second part of this work deals with the preparation of herbal teas and their proper use. t characterizes twenty widely known and lesser-known herbs, which are most often being used to prepare herbal tea and it talks about their effect on human health. Free radicalm oxidative stress, antioxidants, herbal teas, vegetla antioxidants, herbs
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Antioxidanty v bylinných čajích
Procházková, Anna
This bachelor thesis under the name Antioxidants in Herbal Teas concerns in antioxidants which are to be found in plant substances, in their qualities and use with their partially healing or preventive effects in a herbal tea form. Firstly, this work deals with defining what free radicals, oxidative stress and antioxidants are. It divides the antioxidant groups into substances of flavonoid and non-flavonoid nature. Subsequently, it tries to objectively explain their positive as well as negative impact on human organism, e.g. during an excessive intake of these substances or supplied to those with weakened immune system. In its final part, the work deals with the way of herbal tea preparation, characteristics of herbs used for tea mixture production and their ipact on human organism.
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Tea culture. The phenomenon of tea drinking and the related ceremonies in society
Neubauerová, Adriana ; Rychlík, Martin (advisor) ; Soukup, Václav (referee)
This bachelor thesis is concerned with the analysis of tea rituals from a theoretical as well as empirical point of view. The work is divided into two parts. The first chapter is devoted to the analysis of general information about the cultivation, processing and effects of tea. Further chapters deal with rituals and habits associated with the process of drinking tea in specific locations. The second part of the thesis is concentrated on the Czech Republic and its tradition of drinking herbal decoction, picking and processing of necessary plants. A part of this paper is an empirical analysis, which aims to discover if there is any specific ritual, enrooted in the Czech culture, associated with drinking tea and if the Czechs, despite of their preference of Asian tea, trust in the effects of herbal tea. The research was performed by a quantitative method and via questionnaires. The hypotheses were mostly confirmed. Key words: herbal tea, tea, tea culture, rite, ritual
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Antioxidanty v bylinných čajích
Musilová, Eva
This bachelor's thesis "Antioxidants in Herbal Teas" brings a summary of substances with antioxidant properties contained in herbs used for production of herbal teas. The basic terms, e.g. oxidative stress, antioxidant, or free radical, are explained first. The individual groups of plant antioxidants (flavonoids, phenolic acids, terpenoids, chlorophylls etc.) are described in terms of their chemical structure and occurrence. There is also a brief introduction to methods for determining antioxidant activity (DPPH, TEAC, FRAP etc.). The next section focuses on the parts of plants used for production of herbal teas, tea preparation methods and characterization of selected herbs concerning their components with antioxidant effects. The final part of the thesis deals with the importance of antioxidants for human health in relation to particular diseases (cancer, cardiovascular and neurodegenerative diseases etc.).
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Analysis of active substances in instant beverages for child´s nutrition
Jašková, Martina ; Kočí, Radka (referee) ; Márová, Ivana (advisor)
The aim of presented diploma thesis was to characterize baby beverages for early infant feeding. Theoretical part deals with baby foods and beverages including breast milk. Practical part is focused on analysis of active substances in 21 commercially available fruit and herbal instant granular baby beverages and in 3 packaged tea bags for infant and toddler age. To evaluation of antioxidant properties some group parameters were used - total polyphenols, total flavonoids, total antioxidant activity and anthocyanins. All of them were analysed by using spectrophotometrical methods. For identification and quantification of individual phenolic substances was used RP-HPLC/UV-VIS and HPLC/PDA/LC-MS, identification of individual mono- and disaccharides was performed by HPLC/RI. L-ascorbic acid supplemented to some children's drinks was analysed by HPLC-NH2/UV. Protein analysis was performed by Experion microfluidic electrophoresis system (BioRad) and protein concentration was verified by colorimetric method. In general, the highest content of phenolic compounds was shown in tea bags when compared with instant granular beverages that contain mostly added simple carbohydrates. Using contact microbial tests proved immediately after opening and also during manipulation with tea boxes was verified that analysed baby teas are in agreement with strict hygiene requirements for baby beverages.
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Determination of total antioxidation activity of tea pickles in selected sorts of tea
Bartošová, Jitka ; Vitoulová, Eva (referee) ; RNDr.Jana Skopalová, Ph.D. (advisor)
This thesis deals with the total antioxidant activity (TAA) evaluation of various sorts of tea (green, black, half-fermented, white, mate, rooibos and herbal) depending on the process and time of their treatment. The main emphasis is put on testing a new method of measuring the total antioxidant activity by flow coulometry. The results acquired by this method are compared to the results of the chemiluminescent Trolox equivalent antioxidant capacity (TEAC) method which is a standard for measuring the total antioxidant capacity in various materials and raw materials. The work discusses the reasons for the differences in the values found by both methods.
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