|
|
Changes of the content of some active substances in aplle and pear fruits during storage
Matějková, Markéta ; Halienová, Andrea (referee) ; Márová, Ivana (advisor)
In presented bachelor thesis low molecular substances antioxidants found in plant food were described. Antioxidants from apples and pears were studied in detail, particularly their changes during storage in different conditions. Fruit species were described more closely in this study. The theoretical part is focused on ripening and storage of the fruits. The most common diseases of apples and pears are introduced too. In the practical part changes of some antioxidant levels in apples Idared (red-yellow) and Golden Delicious (green-yellow) were analyzed. Apples were stored for 2 months in three various storage conditions – at standard ambient temperature in the lab, in cellar and in refrigerator. In regular intervals samples were taken and levels of low molecular antioxidants (vitamin C, total phenolics, total flavonoids) and total antioxidant activity in apple fruits were analysed and compared. A surface microflora of the apples was analysed during the whole storage time. The most suitable storage conditions exhibited cellar (9 °C, 38,4 %). Phenolic changes in apples were substantially lower than flavonoid changes, while ascorbate content decreased dramatically with the storage time. Antioxidant activity was related mainly to ascorbate levels, influence of flavonoid changes was observed too. Antioxidant parameters were analyzed also in pear fruits, whose were stored only for very short time.
|
|
|
Study of Activity of Enzyma and Low Molecular Weight Antioxidant Systems
Macuchová, Simona ; Kráčmar, Stanislav (referee) ; Čertík, Milan (referee) ; Márová, Ivana (advisor)
Oxidative processes play important role in cell physiology and pathology as well. Balance of these processes is supplied by cooperating antioxidative systems; function of antioxidant defense systems depens on high levels of antioxidants in organism. Presented work is focused on developement and optimization of methods for analysis of important enzyme and non-enzyme antioxidants as well as total antioxidant capacity of selected types of biological material. Extractions and analyses of vitamin E, carotenoids, superoxide dismutase, catalase, peroxidase and lipoxygenase in barley and malt were optimized. RP-HPLC and HPLC/ESI-MS were used for analysis of vitamin E, phenolic and carotenoid content, spectrophotometry was used for enzymes activity analysis. A new methods for catalase and lipoxygenase activities were developed and compared with direct UV methods. Superoxide dismutase activity was determined by commercial diagnostic kit. A colorimetric method was used for peroxidase activity determination. Some kinetic parameters of enzymes were provided too. Optimized methods were used in the analyses of antioxidants in plant material - in barley and malt - in sets of samples of 6 varieties cultivated in four different locations for two years. Content of individual antioxidants differed depending on the variety, but usually were not found significant differences in the levels, depending on growing location. Perhaps climatic conditions have the greatest influence on levels of low molecular weight and enzymatic antioxidants at the specific location; oxidation processes are influenced both the quantity of moisture, both by sunlight, which induces oxidative processes in cultivated plants. The activity of antioxidants in barley caryopses is rapidly increasing during the malting process; an elevated temperature and moistness first induces activation the enzyme systems including antioxidant. In caryopsis is metabolic activity increased during which we can expect an increased production of radicals; for this purpose can antioxidant systems be activated that protect cells from damage by oxidative stress. In the second part of work optimized methods were applied in two clinical trials focused on study of the influence of exogenous antioxidants intake on metabolic and antioxidant status in human organism. In the first clinical study influence of food supplement containing polyunsaturated fatty acids and vitamin E on metabolism of hyperlipidaemics was evaluated. After 3-month supplemenation a lipid profile was improved and serum antioxidant levels increased. The second experiment was focused on enzyme and non-enzyme antioxidant levels in healthy subjects after temporarily intake of specific foods rich in antioxidants. After two-month intake plasma phenolic substances were slightly increased. Total antioxidant capacity and activities of enzyme antioxidants were not affected. Results of both clinical exeriments showed that supplying of antioxidants in natural form or in the form of food supplements does not markedly affect metabolism of healthy subjects, while in patients with chronic diseases antioxidant supplementation can positively influence metabolic status. Results of this work showed that optimized methods are suitable for analyses of antioxidant status parameters and also for monitoring of exogenous antioxidant intake.
|
|
|
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.
|
|
|
The antioxidant activity of selected species of small fruit
Křenová, Alena ; Gregor,, Tomáš (referee) ; Diviš, Pavel (advisor)
This diploma´s thesis deals with the determination of total antioxidant activity of red and white gooseberries and red, white and black currants. There are available information about small fruits, an overview of natural and synthetic antioxidants and a summary of the methods to determine the total antioxidant activity in the theoretical part. Frozen fruit samples were provided by Research and Breeding Institute of Pomology Holovousy Ltd. in the project QI111A141 – Research of new technologies in the cultivation of gooseberries and currants with a focus on quality and use of fetuses (Ministry of Agriculture). The total antioxidant activity of red and white gooseberries and currants was measured by spectrophotometric methods using free radicals ABTS•+ and DPPH and was expressed as a Trolox equivalent. The total antioxidant activity of black currants was measured by electron paramagnetic resonance using free radicals ABTS•+ and DPPH and expressed as a TEACABTS and a TEACDPPH. There were measured 8 species of red gooseberries, 6 species of white gooseberries, 12 species of red currants, 6 species of white currants and 8 species of black currants in this thesis. The highest values of total antioxidant activity showed species of red and white gooseberries Alan, Karmen, Pax and Invicta and species of red and white currants Rovada, Orion and Olin. Among black currants, species Ometa and Ruben had the highest values of total antioxidant activity.
|
|
|
Changes of enzyme activities in fruits during long-term storage
Ferdová, Jitka ; Melounová,, Jitka (referee) ; Márová, Ivana (advisor)
This study is focused on study of changes of enzyme and low-molecular weight antioxidants in different fruits during long-term storage. In theoretical part individual low-molecular weight antioxidants and enzymes are described. The main causes of fruit decay and some possibilities of fruit preservation and storage are summarized. As biological material some common fruits were chosen - green and red apples, peaches, plums and white grapes. The fruits were stored in laboratory, cellar, in refrigerator and in freezer. In freezing experiments some ways of fruit preparation and processing were tested and their influence on fruit antioxidant status was compared. Shortened storage experiment was applied on blueberries, cranberries, raspberries and strawberries too. In fruits some group parameters – total antioxidant status, dry mass content, ascorbate level, total flavonoids and total phenolics were analyzed spectrophotometrically. Individual flavonoids and phenolics were determined by RP-HPLC/UV-VIS and on-line LC/PDA/ESI-MS. Antioxidant enzyme activities (superoxide dismutase SOD, catalase CAT, polyphenol oxidase PPO and lipoxygenase LOX) were measured by spectrophotometry. The surface microscopy and cultivation of moulds from fruit surface were performed too. Influence of storage conditions on biological activities is dependent on fruit sort. Freezing is the most suitable procedure for long-term storage without significant changes of active substance content. Long-term storage in controlled temperature conditions and/or atmosphere is usable for fruits with longer storage period. In these fruits stabile levels of antioxidant enzymes are stored for relatively long time. Some of enzymes act synergistically. Enzyme activities differed according to storage phase; at the beginning mainly high SOD and LOX activities were observed. CAT and PPO are probably activated as defence systems in rippened and/or damaged fruits. Levels of total as well as individual low molecular weight antioxidants varied during storage in all sorts, generally, increased course with longer storage period can be observed.
|
|
|
Influence of storage conditions on content of biologically active substances in apple fruits.
Ferdová, Jitka ; Čarnecká, Martina (referee) ; Márová, Ivana (advisor)
This study deals with antioxidants in diet and their effects on human organism. Further, it summarizes the agents affect the quality of apples in the course of long-term storage and it outlines the possibility of defence against them. In the experimental part methods of determination of antioxidant enzymes superoxid dismutase (SOD), catalase and polyphenol oxidace (PPO) in apples were introduced. The enzymes were measured in apples tissues in liquid nitrogen after 158 days in normal or modified atmosphere. In Apple the quantitative and qualitative analysis of proteins was realized. Further, some low molecular antioxidants (total phenolics, total flavonoids and vitamin C) as well as total antioxidant status were measured in frozen raw juice. This values were compared with values from apples analyzed immediately after the harvesting. Artificial inoculation with fungi was made in the last part and the fruitfulness was observed.
|
|
|
Comparison of an analytical techniques for determination of an antioxidant activity in food
Křenová, Alena ; Vespalcová, Milena (referee) ; Diviš, Pavel (advisor)
This bachelor‘s thesis deals with the characterization of natural and synthetic antioxidants and their effects on free radicals. Natural antioxidants are usually absorbed as a part of complex mixtures and that’s why we try to characterize an antioxidant activity as a whole. Chemical and physical methods have been developed to determine the total antioxidant activity of food. This thesis focuses on chemical methods, specifically on ABTS and DPPH, which are based on a reaction of antioxidants with synthetic radicals. Next chemical method is FRAP, which is based on the reducing ability of antioxidants. In the experimental part, these methods are compared from a perspective of their performance and the results of the analysis of real food samples.
|
|
|
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.
|
|
|
Extraction of anthocyanin pigments from elderberries pomace
Lošková, Tereza ; Pořízka, Jaromír (referee) ; Vespalcová, Milena (advisor)
This Diploma thesis deals with the production of the concentrate from the Elderberry marc extract (Sambucus nigra L.). The basic chemical characteristics in this concentrate were determined. The theoretical part of the thesis deal with the botanic characteristic of the Elderberry and its berries. The characteristic of the phenolic compounds, mainly anhocyanins was summarized. The use of the anthocyanin pigments in the food industry, the possibilities of their extraction and the concentrate production was discussed. Thereafter the methods of the anthocyanin content and the phenolic content determination were described. In the experimental part of study, the production of the anthocyanin rich extract from Elderberry marc was optimized. The extraction of the marc by the 1:1 ethanol/water (V/V) solvent with the ratio marc/solvent 1:2 (w/V) showed the most convenient. The production of the concentrate followed. During the concentration on the rotary evaporator the pigment degradation was investigated. The degradation decreased with the decrease of the temperature. The final concentrate was prepared from the extract on the rotary evaporator by 45 °C for 15 minutes. This product had the 7times lower volume compared to the initial extract. In the final concentrate come of the chemical characteristic were determined. By liquid chromatography (HPLC) the major pigments cyanidin-3-sambubiosid and cyanidin-3-glucosid were determined. Their total content was determined to 34,9 gl-1. The total anthocyanin content was determined by pH differential method to 7,1 gl-1 (expressed as cyanidin-3-glucoside equivalent). The total phenolic content was determined to 27,1 gl-1 (expressed as gallic acid equivalent) by Folin-Ciocalteu method. By electron paramagnetic resonance the increase in antioxidant activity with the increase in concentration was found. Up to 42 aromatic compounds was determined in Elderberry marc, its extract and the final concentrate.
|
|
|
Hodnocení taxonů sortimentu rodu Origanum L. v podmínkách ekologického a konvenčního způsobu pěstování
Veserlová, Monika
The thesis titled Evaluation taxa range of the genus Origanum L. in terms of organic and conventional production system deals with the growing influence of the type for its contents Origanum vulgare L. - essential oil content and total antioxidant activity. Literary section describes the botanical description of the genus, growing practices in ecological and conventional conditions, content and substance use. The practical part of the individual plant specimens in terms of morphological characters, selected phenological characteristics, essential oil content and total antioxidant activity.
|
guest ::
