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Changes of antioxidants in selected fruits during long-term freezing
Štindlová, Jitka ; Lichnová, Andrea (referee) ; Márová, Ivana (advisor)
In this bachelor thesis some low molecular weight antioxidants contained in strawberries, raspberries, blueberries and cranberries are described. In the theoretical part also general characteristics of these fruits are introduced. Experimental part was focused on analysis of the changes of selected antioxidant content in the fruits. These changes were monitored during storage in two different conditions – in refrigerator and in freezer. In refrigerator whole fruits were stored for 8 days. The experiment in the freezer was performed for 2 months and the fruits were stored in four different processed forms – as a whole fruit, whole fruit impregnated by sucrose solution, as a pulp and pulp mixed with sucrose. Antioxidant content in fruits was analyzed by HPLC and spectrophotometry. The highest total content of antioxidants was found in strawberries, while the lowest values were found in raspberries. During storage some part of original antioxidant content stayed conserved, the highest content was preserved in blueberries processed as a whole fruits and impregnated whole fruits.
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Changes in selected local fruits during freezing.
Matějková, Markéta ; Melounová, Jitka (referee) ; Márová, Ivana (advisor)
This diploma thesis was focused on study of low-molecular antioxidants present in various kinds of fruits, namely berries. In theoretical part detailed characterization of antioxidants studied in presented work and their biological effects are introduced. Further, principals of processing and storage of specified species of fruits are discussed. Changes observed during storage of specific fruits are described too. In practical part changes in content of selected antioxidants in berries were followed. As studied material strawberries, raspberries, blueberries, red and black currants were used. All kind of these fruits was stored in fridge for six months using several different kind of processing. Berries were stored as whole fruits, whole osmotically processed fruits by sucrose, raw pulp and sweetened pulp. At first, starting values of selected antioxidant parameters were measured in fresh fruits (ascorbate, total antioxidant activity, total phenolics, catechins and individual flavonoids). After freezing the same parameters were measured regularly in two month periods. As the most suitable method of fruit processing, with regard to antioxidant content, storage of the whole fruits or pulp can be recommended. Content of ascorbate decreased in all forms and species of the processed fruits during all the time of storage. Oppositely, the content of other studied antioxidants exhibited fluctuations or increasing trend. Sensory analysis was proved for the whole fruits and also for whole sweetened fruits.
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Vliv zpracování borůvek na obsah biologicky aktivních látek
Balaščáková, Viktória
This thesis deals with the influence of blueberry processing on the content of bioactive compounds. The aim of the study was to determine and compare the content of bioactive compounds in six types of storage and processing of blueberries. Spectrophotometric analysis was used to determine the content of polyphenols, flavonoids, total antioxidant capacity determined by the TEAC method, and total antioxidant capacity determined by the DPPH method in frozen, oven-dried, freeze-dried, stored at 6 °C, and poorly stored blueberries of the Brigitta variety. The highest content of flavonoids was found in the freeze-dried samples and the lowest content was found in the frozen samples. The highest content of antioxidant capacity determined by the TEAC method was found in the freeze-dried samples. The second highest content of antioxidant capacity by the TEAC method was found in the oven-dried samples. Stored samples in the freezer had the lowest antioxidant capacity content determined by the TEAC method. Samples that were oven-dried had the highest antioxidant properties against free radicals, as determined by the DPPH method. The second-highest content of antioxidant capacity by the DPPH method was found in the freeze-dried samples. Conversely, the lowest value of antioxidant capacity determined by the DPPH method was found in samples frozen at -80°C and -20°C. The difference in values between the freeze-dried and oven-dried samples was very small when determined by the DPPH method. The results indicate that the lyophilization process was identified in this study as the most suitable for preserving bioactive compounds in blueberries.
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The evaluation of 137Cs content in mushrooms and forest berries in the South Bohemia region
HÁLOVÁ, Jana
The collection and consumption of forest fungi and blueberries are among the most popular seasonal activities in Czech Republic. Due to the Chernobyl accident, however, these raw materials are believed to have contained increased amounts of radionuclides. The aim of the work is to evaluate the content of 137Cs in blueberries and fungi collected from South Bohemian region in the period of 1992 - 2020. Data of 137Cs mass activity obtained from the State Office for Nuclear Safety's MonRas database were re-examined for validation using samples of fungi (n = 318) and blueberries (n = 142). The results ranged widely as follows: (a) boletes fungus, from 0.18 to 6430 Bq / kg; (b) leafy fungus, from 0.28 to 4040 Bq / kg; and (c) blueberries, from 0.24 to 2046 Bq / kg. Between boletes fungus and leafy fungus, the former was seen to have a higher ability to accumulate the radionuclide 137Cs. The calculated effective dose caused by the consumption of fungi and blueberries was assessed as negligible, amounting only to less than 1% of the general limit for the population. Despite these favorable results, detailed monitoring of raw materials from nature needs to be continued and the safety of the food chain ensured.
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Comparison of Czech and world superfoods
Soldánová, Lucie ; Vojáček, Jan (advisor) ; Slimáková, Margit (referee)
v angličtině k bakalářské práci na téma "Srovnání českých a zahraničních superpotravin" ,Lucie Soldánová, Karlova Univerzita, 1. lékařská fakulta, obor Nutriční terapeut. This bachelor thesis focuses on the topic of superfoods and aims to discover how our crops differ from those from abroad. The work consists of a theoretical and practical part. In the theoretical part of my thesis, I firstly analyze five most well known foreign (avocado, soy, goji, chia seeds and quinoa) and Czech (various seeds, poppy seeds, walnuts, blueberries and vegetable juices) superfoods. Then I compare them on four levels- a nutritional, economical, ecological and ethical one. In the practical part I asked several questions related to the problematics of superfoods and with the use of sent out questionnaires investigated whether people know superfoods, what is their opinion on them, if they buy them and whether they think about their origin and deeper problematics of the import of exotic crops. I discovered that more than 75 percent of those questioned are aware of superfoods. Whole 40 percent of people were somewhat sceptical of these foods and only 18,5 percent expressed full trust in them. Almost 73 percent of respondents buy superfoods at least once a week, which reflects their more frequent consumption, while the...
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Health importance of phytochemicals in berries focused on weight-reducing diet
VOKOUNOVÁ, Kateřina
Bachelor´s thesis named "Health importance of phytochemicals in berries focused on weight-reducing diet" deals with the weight-reducing diet containing phytochemicals and its health effect on human heatlh. In theoretical part of the thesis, I focused on weight-reducing diet and bioactive substances, and I described phytochemicals and blueberries in detail. The formation of a two-week weight-reducing diet containing polyphenols correspondig with the amount of 120 ml natural blueberries a day was the goal of my thesis. The exploration of food products as fully-fledged sources of polyphenols was my next goal. For the processing of the research I have examined food products containing blueberries, which were made in the South Bohemian region, specifically through interviews with leaders and representatives of various companies and I found all the necessary information about each food products containing blueberries. The amount of polyphenols was determined by HPLC (High Performance Liquid Chromatography) which was conducted under the leadership of doc. MUDr. Petr Petr, Ph.D. I finished counting the amount of polyphenols in some food products from the initial analysis. I have included these products in the weight-reducing diet with any possible adjustments to meet the criteria of weight-reducing diet. I included natural blueberries in many meals in various modifications. The richest sources of natural polyphenols were frozen blueberries and beverages containing natual blueberries. There were natural blueberries refrigerated or frozen, Herbal tea with blueberries or dairy products containing blueberries the most appropriate for the weigt-reducing diet.
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Changes in selected local fruits during freezing.
Matějková, Markéta ; Melounová, Jitka (referee) ; Márová, Ivana (advisor)
This diploma thesis was focused on study of low-molecular antioxidants present in various kinds of fruits, namely berries. In theoretical part detailed characterization of antioxidants studied in presented work and their biological effects are introduced. Further, principals of processing and storage of specified species of fruits are discussed. Changes observed during storage of specific fruits are described too. In practical part changes in content of selected antioxidants in berries were followed. As studied material strawberries, raspberries, blueberries, red and black currants were used. All kind of these fruits was stored in fridge for six months using several different kind of processing. Berries were stored as whole fruits, whole osmotically processed fruits by sucrose, raw pulp and sweetened pulp. At first, starting values of selected antioxidant parameters were measured in fresh fruits (ascorbate, total antioxidant activity, total phenolics, catechins and individual flavonoids). After freezing the same parameters were measured regularly in two month periods. As the most suitable method of fruit processing, with regard to antioxidant content, storage of the whole fruits or pulp can be recommended. Content of ascorbate decreased in all forms and species of the processed fruits during all the time of storage. Oppositely, the content of other studied antioxidants exhibited fluctuations or increasing trend. Sensory analysis was proved for the whole fruits and also for whole sweetened fruits.
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Changes of antioxidants in selected fruits during long-term freezing
Štindlová, Jitka ; Lichnová, Andrea (referee) ; Márová, Ivana (advisor)
In this bachelor thesis some low molecular weight antioxidants contained in strawberries, raspberries, blueberries and cranberries are described. In the theoretical part also general characteristics of these fruits are introduced. Experimental part was focused on analysis of the changes of selected antioxidant content in the fruits. These changes were monitored during storage in two different conditions – in refrigerator and in freezer. In refrigerator whole fruits were stored for 8 days. The experiment in the freezer was performed for 2 months and the fruits were stored in four different processed forms – as a whole fruit, whole fruit impregnated by sucrose solution, as a pulp and pulp mixed with sucrose. Antioxidant content in fruits was analyzed by HPLC and spectrophotometry. The highest total content of antioxidants was found in strawberries, while the lowest values were found in raspberries. During storage some part of original antioxidant content stayed conserved, the highest content was preserved in blueberries processed as a whole fruits and impregnated whole fruits.
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Fytochemical potencial of polyfenols contain in berries
KRUMPHANZLOVÁ, Iva
This thesis sums up findings on polyphenols and their positive influence on human health. In these fytochemicals, unlike in micronutrients, recommended daily amount cannot be estimated. Micronutrient deficiency in food can cause deficiency symptoms, while in polyphenol deficiency, the deficiency does not occur. When they are present in sufficient amount in food, it is considered functional food, which is important for civilization illnesses prevention. At the beginning of the theoretical part, the polyphenol classification from pharmacological and chemical point of view is represented. On the basis of this classification important role of antioxidants and flavonoids is described. Special attention is being paid to resveratrol, which is populardue to its well known "French paradox". The following part considers the polyphenol influence on human health. The way in which polyphenols protect our body from certain diseases is explained in detail. Most of the health benefits are supported by studies conducted on animals. These studies are also mentioned and described in this paper. In the theoretical part the process of absorption and the polyphenols safety for human body is also explained. Polyphenol sources are listed in the last subchapter. The work is mainly aimed at blueberry fruits (Vaccinium myrtillus) and vine grapes (Vitis vinifera). Other berries are briefly mentioned as well, such as cranberries, raspberries, blackberries and currant. The goal of this work is to create a diet that would provide a functional daily amount of polyphenols. This amount can be compared to 120 ml of native blueberries. Only products, consumable without cooking, are used in this diet. The second goal is to chart, which food products are adequate source of polyphenols. On the basis of these goals, research inquiries were defined. Research inquiry No. 1: What amount of polyphenols is contained in berries, especially blueberries. Research inquiry No. 2: Which food products (without cooking) are ideal to be included in diet, to provide adequate daily amount of polyphenols. To asses polyphenol content in blueberries, analysis of polyphenol content acquired through GEOMED program from Nemocnice České Budějovice a.s., department of clinical pharmacology, was used. Assessments were made using the HPLC method (high performance liquid chromatography) in cooperation with the biological centre AV ČR in České Budějovice. Thanks to this analysis, the first inquiry can be answered. An interesting phenomenon is discovered, that frozen blueberries have higher polyphenol content then cooled ones. Malvidin (malvidin-3-6"-acetoyl glycoside) was chosen as priority anthocyan since it is most represented in the blueberry. Remaining information about polyphenol content in certain food products were drawn on Joseph Maroon´s book, MD, FACS (2010). The practical part involves a diet for 14 days, which meets the given requirements. The results clearly show that it is possible to create a diet rich in polyphenols. A list of blueberry products accessible to everyone is included. Blueberry dairy products, jams, beverages, fruit salads and fruit pyre have been analysed. The list shows which product contains the most polyphenols. The required amount can be achieved by the proper combination of given products. The ideal one proved to be 200 ml of red wine and one blueberry dairy product (with the malvidin value higher than 64). Findings in this paper will serve to promote polyphenol awareness and itseffects. This diet can be used in nursing homes, where their positive influence on equilibrium can be applied. It can also be used in spas and other alimentation related facilities.
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