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Encapsulation of natural antioxidants
Štindlová, Jitka ; Obruča, Stanislav (referee) ; Márová, Ivana (advisor)
In theoretical part of this diploma thesis the basic properties of antioxidants, especially anthocyanins and phenolic compounds are described, as well as the basic features and principles of free radicals formation. The theoretical part also describes some possible ways of encapsulation of antioxidants into polysaccharide and lipid particles. In the experimental part basic characteristics of extracts from selected lyophilized fruits and vegetables (carrots, apples and mixed berries) are described. As group parameters of plant extracts the total antioxidant activity, content of flavonoids and phenolics, carotenoids, anthocyanins and ascorbic acid were determined. In experimental part also various encapsulation techniques were tested, encapsulation effectiveness of each technique was evaluated and the stability and size of the created particles were determined. As the best encapsulation method in terms of encapsulation efficiency in most of samples/parameters ethanol injection was found. On the other hand the particles prepared by ethanol injection are relatively unstable in terms of zeta potential, which is followed by their tendency to aggregate. As the most stable particles prepared by thin layer evaporation (TLE) and reverse phase thin layer evaporation (RP-TLE) were evaluated. Particles prepared by TLE, RP-TLE and chitosan-alginate particles exhibited a negative charge, while particles prepared by ethanol injection stayed uncharged and chitosan particles have a positive charge.
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Characterization of organic nanoparticles with encapsulated antimicrobial peptides
Vejrostová, Petra ; Němcová, Andrea (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on characterization of particles containing encapsulated antimicrobial enzyme lysozyme. The theoretical part deals with characterization of antimicrobial peptides and their description. Further part of review was focused on lysozyme, the selected representative used in this thesis, its structure, mechanism of action and possible usage. In the experimental part the Hartree-Lowry method was used for lysozyme detection, determination of encapsulation efficiency and for detecting the amount of lysozyme released after incubation in model physiological environment and in model foods. In process of encapsulation the highest amount of lysozyme was packed into 1% chitosan particles, manually prepared alginate particles and into liposomes. During study of stability of particles in model foods as the least stable manually prepared chitosan particles were found. The released lysozyme exhibited changes probably caused by its degradation. The highest influence on particles proved 3% acetic acid. During studying the stability of the particles in artificial digestive fluids as the most unstable manually prepared chitosan particles were found, while alginate particles were the most stable. The thesis also deals with changes in antimicrobial activity of encapsulated lysozyme in prepared particles and after its application into the model environments. A gram-positive bacteria Bacillus subtilis was used in order to test the antimicrobial activity. Antimicrobial tests showed that after encapsulation antimicrobial activity of lysozyme was substantially decreased in most samples. Size and stability of prepared particles was tested using dynamic light scattering.
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Preparation and stability of core-shell type organic micro- and nanoparticles
Byrtusová, Dana ; Benešová, Pavla (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on possibilities of encapsulation polyphenolic compounds in core-shell type organic micro- and nanoparticles. The theoretical part is aimed at characterization of polyphenolic compounds, their biological effects and their possibilities of encapsulation into various types of particles. The experimental part deals with the content of polyphenolic compounds, flavonoids and anthocyanins in guarana, ginseng ang goji. Extracts from these samples were packed into liposomes and polysaccharide particles. Encapsulation´s effectiveness was determined spectrophotometrically. The stability of particles was monitored for size and stability by dynamic light scattering. The particles were exposed to the model body fluids and model food.
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Encapsulation of lactic acid bacteria
Vrtná, Monika ; Lichnová, Andrea (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on encapsulation of two strains of probiotic bacteria. Lactic acid bacteria were encapsulated into several types of materials, mostly polysaccharides. The theoretical part describes the techniques of encapsulation applicable in the food industry. During the experimental part alginate and chitosan microparticles were prepared. These particles exhibited different sizes and some of them were modified by starch and carboxymethyl cellulose. Particles were used for encapsulation of two strains - Bifidobacterium breve and Lactobacillus acidophilus. Using flow cytometry cell viability was measured after 24-hours cultivation of bacteria. Particles were observed immediately after encapsulation by optical microscopy and then long-term stability in model foods was evaluated after two days, a week and after four weeks of incubation. Using the Bürker chamber the alived and death bacteria were counted inside and outside the capsule. The stability and viability of the cells were studied also in the artificial intestinal, stomach and bile juices. As the best material for encapsulation of lactic acid bacteria 2% alginate modified by carboxymethyl cellulose was found. The highest viability of bacteria was observed in milk as the real model food. Prepared particles are suitable for use in the food industry.
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Encapsulation of some enzymes into organic particles
Hazuchová, Eva ; Obruča, Stanislav (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on encapsulation of some enzymes into organic particles. The theoretical part is aimed to enzymes, their general characteristics, structure, activity and use, and to encapsulation techniques. Some methods used for analysis of particles, namely the determination of the distribution of particle size using dynamic light scattering, and determining the stability of the particles by the zeta potential, are described too. The experimental part describes methods of preparing particles, methods of determining the encapsulation efficiency and methods for determining particle size and stability. During the experiment part four types of enzymes were encapsulated, partly by manual preparation and partly by encapsulator. Encapsulation efficiency, size and stability of prepared particles were determined too. The particles were exposed to artificial intestinal, gastric and bile juices, as well as the effect of model foods. Subsequently, their long-term stability was observed.
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|Preparation and characterization of micro- and nanoparticles with selected drugs
Sosková, Simona ; Bokrová, Jitka (referee) ; Márová, Ivana (advisor)
The presented bachelor thesis is focused on the way to prepare combined micro- and nanoparticles containing some natural extracts with antioxidant effects, ibuprofen as the anti-inflammatory and analgetic agent and clotrimazole as the agent with an antifungal effect. The theoretical part contains an introduction of the methods of liposome preparation and a review of encapsulation techniques, methods of particles characterization, and analysis of active substances content. Furthermore, the yeasts of the genus Candida and the methods of the antimicrobial activity determination are described. The mentioned components were encapsulated into liposomes, alginate and chitosan particles. The antioxidant activity of the extracts was determined spectrophotometrically. The encapsulation effectivity of active substances into particles and the long-term stability of encapsulated components were determined and compared too. The HPLC method was used for measuring of the concentration of drugs and spectrophotometric method was used to quantify the content of polyphenols. Prepared particles were characterized with DLS method (size) and zeta- potential (stability). Finally, antibacterial properties of prepared particles and extracts using the test system Candida glabrata were studied. The antimycotic effect of particles, disturbed liposomes and extracts was compared. Finally, potential utilization of prepared liposomes in a cosmetic or pharmaceutical product is proposed.
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Application of nanoparticles and nanofibers with active compound in cosmetics
Pavelková, Renata ; Obruča, Stanislav (referee) ; Márová, Ivana (advisor)
Presented bachelor thesis is focused on application of nanoparticles and nanofibers with active compound in cosmetics. The theoretical part is aimed at effect of UV radiation on the skin and compounds that are used in photo protection of the skin. The materials and methods used in nanoparticle and nanofiber preparing were characterized. The experimental part deals with preparing of liposomes and marinosomes with active compound. Particles size, stability measured using zeta potential and stability in model environment were observed. Finally, pilot experiments of optimization of nanofibers preparation using electrospinning were carried out.
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Preparation and use of selected nanoparticles in cosmetics
Hoová, Julie ; Němcová, Andrea (referee) ; Márová, Ivana (advisor)
The Bachelor thesis is focused on preparation and use of selected nanoparticles in cosmetics. The theoretical part deals with general characterization and use of caffeine, phenolics and vitamin C in cosmetics. Further, characterization of liposomes and possibilities of encapsulation of active substances gained from natural sources were introduced. In experimental part liposomes with encapsulated active substances were prepared by three different techniques. Encapsulation efficiency was determined by HPLC/PDA, phenolics spectrophotometrically and vitamin C by titration. Prepared particles were monitored for size and stability by dynamic light scattering. Furthermore, long-term stability of liposomes in model conditions was evaluated as the amount of the active substances released during incubation. In this work was found out that from all tested samples co-encapsulated liposomes are probably the best application form which can be used in face lotion or gel. Co-encapsulated liposomes exhibited relatively high encapsulation efficiency, good stability and thanks to quality of active substances they meet customer’s requirements of cosmetic industry.
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Antimicrobial peptides and their application into foods
Janhuba, Filip ; Petrik, Siniša (referee) ; Márová, Ivana (advisor)
The presented thesis is focused on a study of antimicrobial peptides and their potential applications into foods. Two types of antimicrobial peptides were studied in detail - bacteriocin nisin and antimicrobial enzyme lysozyme. In theoretical part an overview of antimicrobial peptides used in food industry was introduced. The experimental part of this work was focused on optimization of methods for the determination of antimicrobial peptides concentration. Commonly used spectrophotometric methods for quantitative analysis of total proteins as well as high performance liquid chromatography were tested. To determine the molecular weight and purity a modified SDS-PAGE with the addition of urea and tricine buffer was performed. Further, encapsulation of nisin into liposome was tested. Encapsulated particles were prepared by three different procedures: by ultrasonication, ethanol injection and TLE. Particles stability, distribution and size were studied by dynamic light scattering. Stability of encapsulated peptides in model conditions and model foods was studied too. Finally, antibacterial properties of the selected peptides using test system Bacillus subtilis were studied. Nisin already showed antimicrobial effect at low concentrations - about 1 µg/ml. The inhibitory effect of nisin was more evident in liquid cultures.
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Alcohol-free beers with herbal extracts
Vyskočilová, Terezie ; Lichnová, Andrea (referee) ; Márová, Ivana (advisor)
This bachelor thesis deals with alcohol-free beers and herbal extracts, which are the beers flavoured with. In the theoretical part the methods of non-alcoholic beer production and the representation of the active ingredients in herbs are described. A total of 7 herbal extracts were prepared and added into 3 non-alcoholic Czech beers. Each variant was examined in order to detect changes of the content of active substances before and after the addition of the herbal extract. The content of polyphenols, flavonoids, bitter substances and iso-bitter acids as well as antioxidant activity were analyzed spectrophotometrically. Using HPLC/UV-VIS analysis a content of catechins was assayed. The two selected flavours were encapsulated into liposome; the particles were tested of size and stability. Sensory analysis of all herbal extracts including the encapsulated ones was performed to determine the response of consumers and flavour preferences.
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