National Repository of Grey Literature 100 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Isolation of active substances with antioxidative properties from lignocellulosic waste
Jurová, Karolína ; Vítová, Eva (referee) ; Kovalčík, Adriána (advisor)
This thesis focuses on isolating active substances with antioxidant properties from lignocellulosic wastes. This work aimed to modify bacterial cellulose (BC) with extracts from grape pomace, which show high antioxidant activity. Grape pomace belongs to the group of lignocellulosic wastes with high content of bioactive compounds such as polyphenols, which contribute significantly to antioxidant efficacy. This work tested the hypothesis that grape extracts can provide antioxidative efficiency to BC. Grape pomace extracts were prepared from grape pomace frozen and lyophilized using a 70% acetone, a 70% ethanol or a 50% ethanol solvent. The highest values of antioxidant activity were determined for the lyophilized extract prepared by extracting grape pomace with 70% acetone. The extracts were further used to modify bacterial cellulose in the form of films (dry BC) and hydrogels (wet BC). It was shown that both forms of BC could be effectively modified using grape pomace extracts, but BC hydrogel achieved higher antioxidant activity compared to BC film. Furthermore, BC with antioxidant activity can be used in various food, cosmetics, and medicine applications.
Possibilities of using rose hips in the food industry
Maráčková, Adéla ; Kovalčík, Adriána (referee) ; Mikulíková, Renata (advisor)
This thesis focuses on the possibilities of using rose hips in the food industry. The aim of this thesis was to design and create sensory acceptable food products which are made from rose hips. A recipe was created for rosehip jams, chutneys and jellies. During the development of the recipe, individual flavors of rosehip products were evaluated. Freshly ground spices combined with fruits and vegetables were used to flavor the products. According to the optimized recipe for chutney, 1 standard and 3 types with spices were produced: chili, allspice and ginger. A recipe for jams was also prepared - 1 standard and 3 types: cardamom, cinnamon and rosehip jam in combination with apple jam in a ratio of 1:1. Finally, a jelly recipe was created - 1 standard and 3 types with spices: cinnamon, allspice and anise. Individual rosehip products were subjected to sensory analysis and their organoleptic properties were evaluated. The sensory analysis was divided into three parts – for jellies, jams and chutneys. The best rated was a sample of rosehip jelly without the addition of spices. Among the jams, the best rated sample was the jam with the addition of cardamom, which was popular with the respondents because of its pleasant and non-traditional taste. For rosehip chutney, the sample without the addition of spices was the best rated. The mass spectrometry method was used to determine the presence of ionones in the samples, the presence of which is typical for rose hips. The presence and concentration of vitamin C, lipophilic substances and total pigments were determined in the respective rosehip products using the high-performance liquid chromatography method. It was verified by the method of high-performance liquid chromatography that a considerable amount of vitamins was preserved even after the preparation of the resulting products, which were heated. The results of the work pointed to the potential of rosehips, which can be used in the food industry.
Study of the production of polyhydroxyalkanoates using selected thermophilic representatives of the genus Aneurinibacillus
Řeháková, Veronika ; Kovalčík, Adriána (referee) ; Pernicová, Iva (advisor)
The subject of the diploma thesis is the production of PHA copolymers by thermophilic Gram-positive bacteria of the genus Aneurinibacillus. The theoretical part is devoted to the general characterization of PHA materials, their properties, use, and also to the production of PHA polymers by these bacteria. The experimental part deals with the production of PHA copolymers using selected thermophilic members of the genus Aneurinibacillus. Firstly, the specific enzyme activity of PHA synthases was determined, and then the production of PHA copolymers was screened using selected lactones (-valerolactone, -hexalactone, -valerolactone) and diols (1,6-hexanediol, 2,3- butanediol and 1,4-butanediol). These experiments were performed with six thermophilic producers by the members of the genus Aneurinibacillus, which were isolated from compost and activated sludge. Tested microbial strains have demonstrated the ability to integrate interesting monomers into the PHA structure, including 4-hydroxyvalerate (represented up to 69.3% of the total PHA), 5-hydroxyvalerate (up to 47.1%), or 4-hydroxyhexanoate (up to 31.9%). Subsequently, a closer characterization of the obtained PHA (which were gained by the production of the best producers) using advanced methods (DSC, SEC-MALS, FT-IR) was performed. Finally, the screening of the PHA copolymers production was performed in laboratory bioreactors.
Microbial synthesis of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)]
Dugová, Hana ; Zemanová, Jana (referee) ; Kovalčík, Adriána (advisor)
This diploma thesis studied the ability of Cupriavidus malaysiensis, Delftia acidovorans and Azohydromonas lata to produce poly(3-hydroxybutyrate-co-4-hydroxybutyrate), [P(3HB-co-4HB)], by using -butyrolactone and 1,4-butanediol as carbon substrates. The objective of this work was the production and characterisation of isolated polyhydroxyalkanoates (PHA). The theoretical part deals with the basic description and classification of polyhydroxyalkanoates. Next, the biosyntheses of the most investigated PHAs were described. The practical section of the work discusses and presents the output of the cultivation of five bacterial strains selected for the production of [P(3HB-co-4HB)], namely, Cupriavidus malaysiensis (DSM 19379), Delftia acidovorans (DSM 39), Delftia acidovorans (CCM 2410), Delftia acidovorans (CCM 283) and Azohydromonas lata (CCM 4448). The effect of the modified cultivation conditions for each of the used bacteria on the PHA production yields was discussed. The produced biomass after the cultivation was characterised spectrophotometrically, gravimetrically and by gas chromatography. Polymers were isolated from the biomass by the extraction in chloroform. The isolated polymers were characterised from the viewpoint of chemical composition, molecular weight and thermal properties by using Attenuated total reflection infrared spectroscopy, Size exclusion chromatography, Differential scanning calorimetry and Thermogravimetric analysis.
Preparation and characterization of packaging films based on beta-keratin
Měšťánková, Zuzana ; Mikulíková, Renata (referee) ; Kovalčík, Adriána (advisor)
This diploma thesis deals with keratin isolation from poultry feather waste and preparation of keratin-polymers composite films utilizing isolated keratin. The main goal was to isolate keratin from poultry feathers by hydrolysis and compare yield of diverse hydrolysis types. The most efficient was hydrolysis using 0.5% sodium hydroxide with yield 480 g of keratin per 1 kg of chicken feathers. Structure, morphology and thermal properties of isolated keratin was analyzed. Comparison with protein molecular weight standard it was revealed that hydrolysis cleaved keratin to macromolecules smaller than 15 kDa. Scan electron microscopy showed that size of lyophilized keratin particles was in the order tens of µm and had an irregular shape. Further, composite films based on isolated -keratin and other polymers were prepared. Thermal analysis showed, the addition of keratin significantly reduced the thermal stability of composite films. Analyses revealed that Polyvinyl alcohol composite films reached the best mechanical properties. For example, an addition of 0.25 g of keratin per 1 g of polyvinyl alcohol increased the tensile elongation by up to 68.9%. Moreover, the film based on chitosan and keratin had antibacterial properties. The results demonstrate that it is able to efficiently isolate keratin from poultry feather waste by alkaline hydrolysis and isolated keratin can be utilized to prepare potentially applicable keratin-polymers composite films.
Production of PHB-HV from grape pomace by employing a pure culture of Cupriavidus necator
Jakešová, Michaela ; Kučera, Dan (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis deal with the production of PHB-HV copolymer employing a pure culture of Cupriavidus necator H16. First, Erlenmeyer flask´s cultivations using pure fructose as a source of carbon were performed. The mode of addition of valeric acid for the synthesis of PHB-HV was studied. Furthermore, the effect of stress factor (ethanol) on PHB-HV synthesis by this microorganism was investigated. The method obtained by optimization in Erlenmeyer flasks was applied to the synthesis of the PHB-HV copolymer in the bioreactor using fructose as a source of carbon, too. Furthermore, after enzymatic hydrolysis, a sugar extract from grape pomace was obtained as a source of carbon for the synthesis of PHB-HV. The fermentation in Erlenmeyer flasks and the bioreactor using an extract of grape pomace was carried out. Using this alternative carbon source 3.51 g/l PHB-HV copolymer was produced in Erlenmeyer flask, 5.06 g/l in bioreactor respectively. In the first case, the proportion of 3-hydroxyvalerate in the copolymer was 23.78 mol. % and in the second one, 9.39 mol. %.
Study of 3D bacterial cellulose production using banana peels as a carbon source
Netopilík, Tibor ; Pernicová, Iva (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis deals with the study of 3D bacterial cellulose production using Komagataeibacter xylinus using banana peels as a carbon source. The theoretical part deals with the comparison of the properties of bacterial cellulose and plant cellulose, different methods of biotechnological production of bacterial cellulose and its use. The aim of the bachelor thesis was to find out whether it is possible to use banana peel as a carbon source for biotechnological production of bacterial cellulose. Banana peels are waste lignocellulosic material produced, for example, in the production of snacks or fruit or dairy beverages in the food industry. HPLC analysis showed that 1 l of hydrolyzate after enzymatic hydrolysis of 100 g of dry banana peels per 1 l of water contained 8.86 g of glucose and 10.46 g of fructose. The hydrolyzate was used as a carbon source for static and dynamic cultivation of Komagataeibacter xylinus. The yields of bacterial cellulose produced by using banana peels or glucose were compared. The use of banana peels hydrolyzate increased the yields of bacterial cellulose about 170 % in the case of static cultivation and about 220 % in the case of dynamic cultivation. Scanning electron micrographs of bacterial cellulose confirmed the morphological differences between bacterial cellulose produced statically and dynamically. Moreover, the morphology of bacterial cellulose was influenced by the kind of used carbon source.
Use of technical hemp in acne preparations
Žáčková, Kristýna ; Kovalčík, Adriána (referee) ; Němcová, Andrea (advisor)
Hemp belongs among important plants with a long industrial tradition. However, its first use was originally for healing. In medicine, it is mainly applied thanks to the content of many biologically active substances, such as cannabinoids. This thesis is concerned with the use of hemp in acne preparations. The theory focuses mainly on the characterization of hemp and its active substances. The other chapters deals with cosmetic preparations and acne itself, and Propionibacterium acnes as well, which is involved. Within the experimental part, the extracts of two hemp varieties (Finola and Bialobrzeskie) were characterized in terms of antioxidant and cannabinoid presence. The cosmetic preparations with hemp extract content were prepared including a complete cleansing set for acne skin, concurrently commercial products of this sort were purchased. In cosmetic preparations and the extracts their inhibitory effect against Propionibacterium acnes was studied as well. Also Micrococcus luteus, Escherichia coli and Candida glabrata were tested. The results show that dried hemp flower extracts contain the greatest amount of active substances, so they have a higher antioxidant and antimicrobial effect. The presence of individual cannabinoids differed mainly depending on the variety. All hemp extracts had effect against gram-positive bacteria, in cosmetic preparations it was lower. Nevertheless hemp antibacterial effect has been proven.
Determination of the effect of dog rose (Rosa canina L.) on the oxidative stability in fresh juices
Borová, Šárka ; Mikulíková, Renata (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis aimed to determine the content of bioactive substances and antioxidant activity in ethanolic extracts of rose hips fruits (Rosa Canina L.). This work verified the possibility of using the rosehip ethanolic extract as an antioxidant to inhibit the oxidation of fresh pear juice. The ethanolic extracts were prepared by extracting rose hips fruits in various ratios of fruits to the volume of 40% ethanol for 7-28 days. After determining the total content of carbohydrates, polyphenols, flavonoids and vitamin C, it was found that, in principle, the range of the defined substances increases with the ratio of rosehip fruit to the volume of ethanol solution as well as with the extraction time. Ethanol rosehip extracts have also been shown to possess significant-high antioxidant activity. The stabilizing effect of rosehip fruit extract against the oxidation of fresh pear juice was determined spectrophotometrically. It was found that rosehip fruit extracts could inhibit the oxidation of fresh pear juice and have the potential as a natural stabilizer of fresh fruit juices.
Smart food polymer layers
Valíková, Michaela ; Kovalčík, Adriána (referee) ; Veselá, Mária (advisor)
Smart packaging represents a group of packaging with great potential when used in the food industry. Active packaging can have a positive effect on the condition of stored food and smart packaging can inform consumers about the condition of stored food. In the theoretical part, a search was made on the topic of packaging in the food industry, with emphasis on active and intelligent packaging, including the legislative framework. The substances from which smart packaging is made have been described. In the experimental part, partially water¬insoluble polymer layers were prepared from gelatin, glycerol, crosslinking agent and anthocyanin extract. Glutaraldehyde or tannic acid was used as a crosslinking agent. Anthocyanins were obtained by extraction from red cabbage. The total concentration of anthocyanins in the extract was determined by the difference method. For prepared layers, their water solubility was measured and the colour response to the pH environment was evaluated spectrophotometrically. The stability of the layers over time was also monitored. It was found that the prepared layers are able respond to changes in pH.

National Repository of Grey Literature : 100 records found   1 - 10nextend  jump to record:
See also: similar author names
2 Kovalčík, Andrej
Interested in being notified about new results for this query?
Subscribe to the RSS feed.