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Vitamin C
Juráňová, Jana ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
The theme of this diploma thesis is an assessment of given nutritional parameters in selected kinds of lesser known fruits, specifically 10 varieties of sea buckthorn (Hippophae rhamnoides L.), 12 varieties of cornelian cherry (Cornus mas L.) and 6 varieties of blue honeysuckle (Lonicera caerulea var. kamtschatica). Harvests of two consecutive years (2011 and 2012) were analyzed in the case of blue honeysuckle. The theoretical part was focused on historical, morphological, taxonomic and nutritional aspects of individual plants and food or pharmaceutical utilization. The considerable part of the thesis is devoted to the characterization and the possibilities of determining the contained substances, namely ascorbic acid and polyphenolic compounds, especially anthocyanins. The content of the experimental part was a description of the methods and the results of the analysis of total solids, titratable acidity, total phenolics, total anthocyanins and ascorbic acid in fruits of the selected varieties of the above mentioned fruit species. Based on the measured results, the different varieties of fruits were compared to each other and evaluated.
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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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Comparison of the fruits of some honeysuckle varieties in terms of content selected biologically active compounds
Veselý, Ondřej ; Diviš, Pavel (referee) ; Vespalcová, Milena (advisor)
This thesis is focused to the analysis of selected varieties of honeysuckle kamtschatica (Lonicera caerula var kamtschatica) and their comparison in terms of the content of biologically active substances. There were analysed only varieties grown in 2014. Theoretical part elaborates and characterized various parameters of biologically active compounds such as phenolic, anthocyanins and ascorbic acid and possibilities of their determination. Further it briefly surveys Kamchatka honeysuckle, its taxonomic and morphological properties and its nutritional properties. The experimental part of the work was focused on the description of the methods used for the analysis of biologically active substances and their analysis. Polyphenolic compounds and anthocyanin’s were determined spectrophotometrically and vitamin C was determined by high-performance liquid chromatography. The results and varieties were compared with each other. Overall, we can say that the variety with the highest content of all three analysed biologically active substances is a variety Valchová, which had the second highest content of polyphenolic compounds (546.3 mg · 100 g-1 fruits), the third highest contend of ascorbic acid (35.1 mg · 100 g-1 fruits) and the sixth highest content of anthocyanin (170.8 mg · 100 g-1 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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The influence of tomato ketchupes production technology on retention of nutritionally significance ingredients
Smolka, Bronislav ; Voldřich, Michal (referee) ; Ing.Helena Čížková, Ph.D. (advisor)
The work was focused on the verification of influence of quality of raw material and time-temperature conditions on the retention of nutritionally and sensory important components of the ketchups and other tomato based products. The goal of the theoretical part of this diploma thesis was the optimization of procedure of Czech tomato cultivar selection according to the highest refraction and intensive red colour. The influence of tomato ketchups production technology on retention of nutritionally significant ingredients was observed within the practical part. The samples of ketchups were sampled during different steps of production within one batch in company OTMA Sloko Mařatice. It was ketchup which was preserved by pasteurization in the glass bottle and ketchup which was preserved by hot filing to the plastic bottles. The content of lycopene, ascorbic acid, colour, viscosity, refraction and pH were measured in those samples. Furosine had been chosen as marker of thermal stress on material. The technologies can be compared on the basic of measured values from the view of retention or changes of nutritionally and sensory important components.
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Spectrophotometric determination of ascorbic acid in coloured samples
Moravcová, Gabriela ; Vespalcová, Milena (referee) ; Hrstka, Miroslav (advisor)
This bachelor’s thesis deals with spectrophotometric determination of ascorbic acid after the xylen extraction in coloured samples. The theoretical part deals with reactions, biochemistry and occurrence of ascorbic acid in foodstuffs. Also, it is dealt with various methods of determination of ascorbic acid, such as HPLC methods, electrochemical methods, titrimetric determinations, spectrophotometric determinations or polarographic method. In the experimental part of this method were first determined the concentration of ascorbic acid in the standards, then in real samples (vitamin tablets, orange juice and the juice of cultivated varieties of elderberry). Some validation parameters of the method were also determined. Sensitivity of the method was determined to 1,6772, linearity to 0,9990, limit of detection was set at 0,0466 mg/ml and the detection limit at 0,1552 mg/ml. Accuracy of the method was expressed as relative standard deviation, which gained 3,00% in value.
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Electrochemical sensor for ascorbic acid detection
Hlavička, Michal ; Kynclová, Hana (referee) ; Majzlíková, Petra (advisor)
This work deals with electrochemical detection of ascorbic acid using screen-printed three-electrode sensors. The work is divided into three parts, where the first describes the theory of thick-film technology, including the types and compositions of the pastes, fabrication and firing. The second part deals with the methods, measurement principles and the electrochemical detection of ascorbic acid. Experiments were done using screen-printed carbon electrodes in a solution of phosphate buffer and ascorbic acid. In conclusion the results are evaluated.
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Využití nanomateriálů pro zvýšení biodostupnosti doplňků stravy
Vašíčková, Kateřina
Bachelor thesis with the name Application of nanomaterials for enhancement of food supplements bioavailability deals with the effect of selected food supplements on human organism and the use of nanocarriers to improve their biological availability for organism. Literary part of this work is focused on the evaluation of problems of bioavailability of active food components. Then, the benefits and risks of taking food supplements are discussed, including model dietary supplements such as ascorbic and folic acids. The practical part of this work serves to evaluate the long-term stability of complex formed by protein nanocarrier (based on natural iron-storage protein apoferritin) with encapsulated molecules in various light conditions (ambient light, dark), temperatures (-20; 4; 20 and 37 C) and solvents (ACS water, PBS). Stability of this complex, the amount of prematurely released molecules and the size and shape of the nanocarrier were detected using absorbance and fluorescence of the encapsulated fluorescent tag, dynamic light scattering and transmission electron microscopy. The optimal storage conditions were dark, temperature of 4 C and ACS water as a solvent. Moreover, the capability of apoferritin to bind food supplements to apoferritin was researched. Different concentrations of ascorbic acid (615; 308; 154; 77 a 38 ug/ml) were successfully encapsulated to apoferritin when 39 % of all applied molecules were encapsulated. Folic acid was bonded on the surface of apoferritin in five different concentrations (200; 100; 50; 25 a 13 uM) using zero-length linker with 61 % efficiency. Finally, the stable complex of apoferritin with folic acid was applied to cellular line of neuroblastom UKF-NB4. It was discovered that higher concentration of encapsulated folic acid increased the amount of its internalization to cells. Therefore, the increase in bioavailability of folic acid and encapsulated molecules via nanocarriers was proved. The results of this work prove that the use of nanomaterials is applicable to food sector and at the same time can serve to improve the bioavailability of active substances during taking of dietary supplements.
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Technologie výroby a jakost hroznového moštu
Floriánová, Jana
The thesis deals with the production of grapes musts, their quality and sensory profile. The theoretical part describes the chemical composition of grapes, production technology and methods of increasing the shelf life of musts. The practical part is divided into thee larger units. The first part deals with the two varieties used and their origin. It also deals with the technology of grape must production. The second part is devoted to the analysis of must, such as pH, spectrophotometric color measurement and content of ascorbic acid. The last part of the practical part is devoted to sensory analysis of grape musts. There was no difference in pH values that had different pasteurization temperatures. The highest content of ascorbic acid was measured in fresh must, followed by must, which was heated to 80 ℃. The lowest ascorbic acid content was measured in the must, which was heated to 65 ℃. The sensory analysis revealed a difference in colour assessment ant he presence of foreign particles the varieties.
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Stanovení vitaminu C v doplňcích stravy
Ovchynnikova, Oleksandra
The thesis „Determination of Vitamin C in Food Supplements“ is concerned with the comparison of vitamin C concentration levels in effervescent tablets and bulk mixtures stored in tubes with different closures (molecular sieve, silica gel, and the solitary closure) after a certain storage time. Two batches of dietary supplements for adult and juvenile populations were analyzed (Revital vitamin C 500 mg and MaxiVita Kids Multivitamin containing 40 mg of vitamin C). Measurements were taken 6 months after production, then after 10 months and after 14 months of storage. The content of vitamin C was determined by the titration method and high performance liquid chromatography (HPLC). The types of closures, batches of products, individual measurements and methods of vitamin C determination were compared. Based on the measurements, it was found that after some time the concentration of vitamin C decreased significantly. Nevertheless, the type of closure did not significantly affect the vitamin C level in effervescent tablets and bulk mixtures.
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