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Biological effects of various hemp fractions
Vacková, Hana ; Skoumalová, Petra (referee) ; Němcová, Andrea (advisor)
Cannabis is the only plant which contains cannabinoids and thanks to these compounds it has enormous potential. This thesis deals with the analysis of technical hemp. Effects of cannabinoids and methods used for cannabis analysis are discussed in the theoretical part. The experimental part includes spectrophotometric characterization of cannabis, it´s antimicrobial effects and thin layer chromatography analysis. Three sorts of Cannabis sativa L. were analyzed, namely Finola, Fedora and Kompolti. Firstly, the content of polyphenols, flavonoids and antioxidant activity in prepared tinctures were determined. Moreover, antimicrobial test were performed using disk test and turbidity determination. Gram-positive and Gram-negative bacteria and yeast organism were tested. It was found that cannabis tinctures possess good antimicrobial effects. Some of them are comparable with synthetic antibiotics. Finally, thin layer chromatography enabled visualization of cannabinoids in prepared tinctures.
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Study of the antimicrobial effects of selected spices
Kalábová, Jana ; RNDr.Eva Dvořáčková (referee) ; Voběrková, Stanislava (advisor)
The antimicrobial effects of cinnamon, clove and ginger (grand and fresh) extracts against Bacillus subtilis, Aspergillus niger and Pichia fermentans were studied in this thesis. Selected spices were extracted in three solvents (ethanol, water and ethyl acetate) and inhibition effect on tested microorganisms was studied using two methods disc diffusion and broth dilution methods. The antioxidant activity and total polyphenolic compounds from spices were also determined. The results showed that cinnamon and clove extracts in ethyl acetate and ethanol were a promising antimicrobial substances for all tested microorganisms. Combination of cinnamon and clove especially ethyl acetate extracts showed an aditive effect. However, in the case of broth dilution method, fresh ginger inhibited bacterial growth under optimal growth conditions of Bacillus subtilis (35 °C, pH 7, 250 rpm). Minimum inhibitory concentration (MIC) values for all susceptible microorganisms was determined 8,3 mg/ml. The highest amounts of polyphenolic substances were found in cinnamon and clove ethanol extract and this result was in correlation with antioxidant activity.
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Photocatalytic inactivation of yeasts
Šupinová, Lenka ; Zita, Jiří (referee) ; Veselá, Mária (advisor)
This diploma thesis is focused on the study of the effect of ultraviolet radiation and titanium dioxide on the yeast Candida vini. Photocatalytic inactivation of this yeast was performed on various types of titanium dioxide films, which were immobilized on soda lime glasses. Acridine orange was used as a dye to distinguish live and dead yeast cells after certain irradiation time. Live and dead cells emit different light in colour after staining in acridine orange. Candida vini photocatalytic inactivation depends on the amount of titanium dioxide immobilized on glass as well as on the structure of its surface if the lamp intensity remains the same. Kinetics of this photocatalytic process was studied, too.
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Využití silic v potravinářství
Bartuňková, Petra
The bachelor thesis deals with the mapping of the different possibilities of using essential oils in food. In first part, there are described families, which are very important according to their ability of essential oil production, followed by characterization of essential oil composition and compounds and the end methods of extraction. Further, the great attention is dedicated to antimicrobial and antioxidant effects of essential oils. Essential oils are generally regarded as safe, natural and very effective agent against yeasts, molds and bacteria and also against to food spoilage and oxidation (rancidity of fats). The last part of thesis is formed as tabular summary of twenty most used essential oils and their characteristics, means from which plants and plant parts is extracted, the main component and for what purposes it is used. Significant families regarding with uses in the food industry are: Lamiaceae and Apiaceae.
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Vliv účinných látek z rostlin na kvasinky kontaminující mléko a mléčné výrobky
Javorský, Jan
The purpose of this graduation theses is to enlighten the mechanism which influences active substances from plants in specific yeasts types. Literature research focuses on yeasts and their importace in dairy as well as antimicrobial influence of active substances in plants. Three types of essential oils were selected for the purpose of experimental determination; essential oil from melissa, essentiaĺ oil from rosemary and essential oil from thyme. Antimicrobial effect of essential oils was tested on specific yeasts types, isolated from specific dairy products samples. The next step after yeasts identification was testing antimicrobial influence of essential oils using disk diffusion method and broth dilution method. The influence of essential oils was tested in two concentrations, 1 % and 10 %. The best result employing the disk diffusion method was achieved using 10 % concentration essential oil from melissa. Essential oil from rosemary resulted as worse option. The best effect employing the broth dilution method was measured when using the essential oil of rosemary, whereas the essential oil derived from thyme showed the least effect.
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