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Analysis of drinks sweetened with stevia extracts
Procházka, Václav ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
The steviolglycosides are the natural, sweet substances from Stevia rebaudiana Bertoni. It affect human health positively and its sweetness is 300x stronger than the sweetness of sucrose. That's why it's used to sweetening the commercial products. Because of its potential properties it's good to have an appropriate method to isolate it. High performance liquid chromatography ( HPLC) is based on the separation of analyte between two immiscible phases with high pressure pump and appropriately chosen stationary phase in the column. Than the analytes come out from the column in different retention times. This master´s thesis follows up selection of the best HPLC system for isolation of the main steviolglycosides and its analysis in commercial products. In the theoretical part of the thesis is described the origin, basic characteristics, botanical description, cultivation and affect to the human health of Stevia rebaudiana Bertoni and its use in food industry. There are also concisely characterized the sweet substances contained in the plant, so called steviolglycosides. Than there are given the theoretical basics of high performance liquid chromatography, HPLC instrumentation and its specific applications at sleviolglycosides with the basic chromatographic parameters. The object of the first experimental part was to research the optimum conditions for time and separation effective chromatographic analysis and select the best chromatographic system for isolation of steviolglycosides. In the second experimental part, I have compared and defined the main steviolglycosides (stevioside, rebaudioside A) in nine selected products, commercially available in Czech republic, with the best chromatographic method. In these products was the contain of the stevioside or rebaudioside A confirmed or refused.
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Determination of steviol glycosides in beverages
Porubčanová, Vladimíra ; Diviš, Pavel (referee) ; Vespalcová, Milena (advisor)
This diploma thesis deals with sweet substances from Stevia rebaudiana and with their determination in beverages. The ambition was to adjust the separation method for major steviol glycosides (stevioside and rebaudioside A) by HPLC so as to be fast and effective enough, too. In experimental part was successfully developed the separatin method, so it is possible to determine the steviol glycosides and conservation substances, specifically benzoic and sorbic acid (eventually their sodium or potassium salts). At first, for analysis was used monolithic column, on which stevioside and rebaudioside A weren´t separated. Other analyses were performed on column Ascentis express C18 (150 x 4.6; 2.7 µm). The most suitable separation method was performed by mobile phase made up with 29:71 v/v mixture of acetonitrile and acetate buffer (with pH 4.2). The flow rate was 0.28 ml/min and the column temperature was kept constant at 50 °C. The analysis of steviol glycosides and conservation substances with these condition was verified on the samples of real beverages.
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Stevia rebaudiana - food and pharmaceutical industry applications
Rücker, Matěj ; Drastík, Martin (advisor) ; Kuchařová, Monika (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Candidate: Matěj Rücker Supervisor: Ing. Martin Drastík, Ph.D. Title: Stevia rebaudiana - food and pharmaceutical industry applications The first part of this thesis deals with the description of the plant and its substances, the most important are steviolglycosides, especially stevioside and rebaudioside A. In the following chapter, the toxicity and safety are evaluated, which is directly related to the use of stevia and steviolglycosides in food and pharmaceutical practice. In the next part, the utilization in the food industry and connected legislation is described. The harmfulness of the refined sugar is outlined as well. Application in the pharmacy is not so widespread, therefore this chapter deals primarily with the effects of steviolglycosides. Stevia rebaudiana Bertoni and steviolglycosides have great potential to replace sugar and other sweeteners. Due to their beneficial effects, they are very popular among researchers, so we can look forward to their widespread application in food and pharmaceutical industry in the near future. Key words: steviolglycosides, stevioside, rebaudiosede A, sugar, pharmaceutical industry, food industry
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SPE in steviol glycosides analysis
Dalecká, Karolína ; Drastík, Martin (advisor) ; Kubíček, Vladimír (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Candidate: Karolína Dalecká Supervisor: Ing. Martin Drastík, Ph.D. Title: SPE in steviol glycosides analysis In the first part of this diploma thesis, the solid phase extraction method is described. The topics like the workflow, usability of sorbents and their formats and interactions with analytes are covered. The second part of this thesis is focused on utilization of solid phase extraction on samples containing steviol glycosides. An overview of solid phase sorbents their forms; solvents used for extraction and elution of steviol glycosides is provided in the discussion section at the very end of this work. Taking into account the fact that stevia has been used more and more on the European market in recent years, and is found in more food and other products, the frequency of determination of steviol glycosides and the use of solid phase extraction is on rise. The most commonly extracted samples include food products with steviol glycosides used as sweeteners or extracts of dried stevia leaves. The main sorbents used for solid phase extraction include silica gel with octadecyl and divinylbenzene-co-vinylpyrrolidine copolymer. This type of extraction is most often connected with high...
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Porovnání senzorických vlastností džemů slazených steviol-glykosidy a dalšími sladidly
KÜFFNEROVÁ, Nela
The aim of the diploma thesis was evaluation of sensoric attributes of blueberry and current jams sweetened by selected Steviol glycosides and their comparing with other sweeteners. For evaluation of sensoric attributes were used rebaudioside A, stevioside, aspartame, erythritol and sugar beet. Stevia rebaudiana var. Bertoni is a persistent plant, which contains sweetening Steviol glycosides, which have a use in food processing. They are available in the area of EU indicated as E960 since 2011. The most used Steviol glycosides are stevioside and rebaudioside A, which are demarcated with a high sweetness, which could be 200-400 times higher than saccharose. The usage of sweeteners is legislatively allowed, which means it is also allowed to do sensoric analyse and detect perception of added substances in food. These analyses evaluate food with the help of sense - perception. Methodical part of the work contains procedure, used methods for gaining evaluation of data from a sensoric analyse after the degustation of jams, which has taken place with the presence of ten judges - an academic students in the working compartment of University of South Bohemia. Respondents entered their evaluation into protocols, which were prepared in advance. The results of diploma thesis are evaluated by the method of Kramer, which is used for this kind of analyse. The critical scale between 20 and 40 with the value of probability P = 95% was defined according to this method. Evaluation is described with the help of graphs and tables, added with a wordily describtion. Conclusion of analyse of diploma thesis is, that the usage of Steviol glycosides is not most suitable way of sweetening jams. Acceptable valuations of jams containing Steviol glycosides were proven in parameters of colour and aroma. The reasons for less successful evaluation of Steviol glycosides could be due to bad pH of food or badly chosen dosing, without combination of other kinds of sweeteners. The best sensory characteristics traditionally showed sugar beet and aspartame followed by rebaudioside A and stevioside, which were placed on the third and forth place from five used sweeteners. The part of the diploma thesis was an evaluation of questionnaire, where the result was, that asked people preferred fruit ingredient of jams (type of fruit, amount) not their way of sweetening while choosing a jam.
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Determination of steviol glycosides by HPLC
Hollá, Marcela ; Drastík, Martin (advisor) ; Kubíček, Vladimír (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Candidate: Marcela Hollá Supervisor: Ing. Martin Drastík, Ph.D. Title of Diploma Thesis: Determination of steviol glycosides by HPLC A new HPLC method was developed and validated for simultaneous detemination of major steviol glycosides stevioside and rebaudioside A in food supplements. Separation took place in hydrophilic interaction chromatography mode on column with core-shell particles. The method was aplicated on analysis of steviol glycosides in products Valosun, SlaDIA, Solia and extract from dried stevia leaves. Isocratic separation was performed using Kinetex 2,6u HILIC 100A, (100 x 2,1 mm; 2,6 µm), Phenomenex analytical column with mobile phase consisted of acetonitrile/0,05 M ammonium formate adjusted with formic acid to pH=3 in ratio 90:10, with flow rate 0,7 ml/min, column temperature set at 30 řC, pressure 19,8 MPa, UV detection at 203 nm and injection volume 1 µl. We compared the results of the analyzes with content of stevioside glycosides declared by the manufacturer. The new developed method allows rapid analysis of food supplements and plant extract containig steviol glycosides. Key words: steviol glycosides, stevioside, rebaudioside A, Stevia rebaudiana Bertoni, high...
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Determination of steviol glycosides in beverages
Porubčanová, Vladimíra ; Diviš, Pavel (referee) ; Vespalcová, Milena (advisor)
This diploma thesis deals with sweet substances from Stevia rebaudiana and with their determination in beverages. The ambition was to adjust the separation method for major steviol glycosides (stevioside and rebaudioside A) by HPLC so as to be fast and effective enough, too. In experimental part was successfully developed the separatin method, so it is possible to determine the steviol glycosides and conservation substances, specifically benzoic and sorbic acid (eventually their sodium or potassium salts). At first, for analysis was used monolithic column, on which stevioside and rebaudioside A weren´t separated. Other analyses were performed on column Ascentis express C18 (150 x 4.6; 2.7 µm). The most suitable separation method was performed by mobile phase made up with 29:71 v/v mixture of acetonitrile and acetate buffer (with pH 4.2). The flow rate was 0.28 ml/min and the column temperature was kept constant at 50 °C. The analysis of steviol glycosides and conservation substances with these condition was verified on the samples of real beverages.
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Analysis of drinks sweetened with stevia extracts
Procházka, Václav ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
The steviolglycosides are the natural, sweet substances from Stevia rebaudiana Bertoni. It affect human health positively and its sweetness is 300x stronger than the sweetness of sucrose. That's why it's used to sweetening the commercial products. Because of its potential properties it's good to have an appropriate method to isolate it. High performance liquid chromatography ( HPLC) is based on the separation of analyte between two immiscible phases with high pressure pump and appropriately chosen stationary phase in the column. Than the analytes come out from the column in different retention times. This master´s thesis follows up selection of the best HPLC system for isolation of the main steviolglycosides and its analysis in commercial products. In the theoretical part of the thesis is described the origin, basic characteristics, botanical description, cultivation and affect to the human health of Stevia rebaudiana Bertoni and its use in food industry. There are also concisely characterized the sweet substances contained in the plant, so called steviolglycosides. Than there are given the theoretical basics of high performance liquid chromatography, HPLC instrumentation and its specific applications at sleviolglycosides with the basic chromatographic parameters. The object of the first experimental part was to research the optimum conditions for time and separation effective chromatographic analysis and select the best chromatographic system for isolation of steviolglycosides. In the second experimental part, I have compared and defined the main steviolglycosides (stevioside, rebaudioside A) in nine selected products, commercially available in Czech republic, with the best chromatographic method. In these products was the contain of the stevioside or rebaudioside A confirmed or refused.
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Stevioside and rebaudioside use in the food industry in the Czech Republic and the European Union
PRAYER, Radek
The main objective of this work was a search process can use steviolglycosides in foodstuffs within the Czech Republic and the European Union in the period since 2000, focusing on legislation and non-food use. Based on journal articles and available legislative provisions, it is clear that Stevia is a plant with great potential to replace at least part of the current sweeteners. Stevia can also be used in cosmetics or in medicine because it contains substances that are beneficial to health. Legislation currently in force in the European Union and the Czech Republic permitted in food use steviolglycosides in high purity. Using Stevia plants or parts thereof, as food is not allowed.
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Sweeteners (natural and artificial) used in the food industry
PIHLÍK, Pavel
The aim of this work is to introduce the sweeteners which are used in the food industry in the Czech Republic but also in the world. The basic sweetener which is a measure of the other sweeteners is regarded as sugar (sucrose). In this bachelor´s work, I described the history of the production of beet sugar in the Czech Republic, the products which are made of it and also its usage in food industry. Furthermore, I introduce the basic types of sweeteners by which we try to replace the beet sugar. I describe the history, production, characteristics and their usage. These are mainly the natural sweeteners which are divided into the carbohydrate (sucrose, fructose, glucose, honey, lactose and sugar alcohols), non-carbohydrate (stevioside, thaumatin) and artificial align (aspartame, saccharin, cyclamates, acesulfame-K, sucralose).
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