This diploma thesis focuses on antibacterial effect of plant oils containing medium-chain fatty acids (MCFA). The minimum inhibitory concentration (MIC) of eight chosen plant oils was defined as the mode of the lowest concentrations that were able to reduce the bacterial growth of 13 pathogenic and 6 beneficial intestinal strains of bacteria by 80 %. Coconut (Cocos nucifera), palm, red palm and palm kernel (Elaeis guineensis), Cuphea (C. lanceolata and C. ignea), babassu (Attalea speciosa, syn. Orbignya speciosa), tucuma (Astrocaryum vulgare), and muru-muru (Astrocaryum murumuru) oils were selected. Their antibacterial activity was tested towards following bacteria: Bifidobacterium animalis, B. longum, Campylobacter jejuni, Clostridium perfringens, Enterococcus cecorum, Escherichia coli, Lactobacillus acidophilus, L. fermentum, Listeria monocytogenes, Salmonella enteritidis, S. infantis, S. typhimurium and Staphylococcus aureus. To identify the fatty acids composition of tested oils a gas chromatography was used. Consequently, the MIC of each oil towards all the bacteria was determined by a broth-microdilution test in 96-well microtitration plates. The essentiality of cleavage of selected oils by lipase was observed, in order to activate their antibacterial effect. None of the tested oils exhibited any potential to inhibit the growth of Gramnegative bacterial strains even after cleavage. Furthermore palm and palm red oil did not exhibit any antibacterial action towards any of the tested bacterial strains. The strongest antibacterial activity was observed in tucuma oil, that inhibited C. perfringens by MIC=0.14 mg/ml. Other oils inhibited the growth of C. perfringens in concentrations from 0.25 to 4.5 mg/ml. The growth of E. cecorum was inhibited by coconut, babassu, Cuphea, palm kernel, muru-muru and tucuma oil in MIC range between 1.12 - 4.5 mg/ml. The only compound active against L. monocytogenes was Cuphea oil (MIC 1.12 mg/ml). Oils that were able to inhibit the growth of S. aureus strain showed MIC from 0.56 to 2.25 mg/ml (coconut, babassu, Cuphea, palm kernel, muru-muru and tucuma oil). Undetected susceptibility of B. animalis, B. longum, L. acidophilus and L. fermentum bacterial strains to tested oils was evaluated as a positive effect. According to the foregoing statements, it can be concluded that the plant oils containing MCFA show antibacterial effect towards Grampositive strains of bacteria after their cleavage by lipase. No showed influence to beneficial intestinal microflora can be a big advantage.

The thesis aims to evaluate the impact of aliment with higher contents of unsaturated fatty acids, consumed for a different period of time, to utilitarian attributes of pigs before a slaughter, with respect to the composition of fatty acids in the intramuscular fat of tested animals. The factors that influence the quality of meat are interior, exterior and technological. Among the qualitative markers of quality of meat we rank the share of meat and fat, acidification rate, color, viscosity, contents of intramuscular fat (marbling), smell, taste, juiciness and delicacy. Together with hygienic and nutritive attributes, consumers and processors consider these technological and sensory aspects to be the most important. The ultimate goal of this thesis is to compare the impact of different length of feeding soy oil on parameters of pork meat quality and growth. However, the interference of growth attributes was inconclusive and the test result came similar in different groups of tested pigs. What was influenced by adding the soy oil into the feed is the fatty acids profile. The contents of fatty acids remained unchanged in every test group. Over time the content of monounsaturated fatty acids decreased. The most significant change occurred in representation of polyunsaturated fatty acids, which increased in the test groups with longer period of feeding with enriched feed, mostly at the expense of monounsaturated fatty acids. The differences between the test groups of pigs were statistically inconclusive; therefore the soy oil enrichment did not worsen the technological parameters of meat and fat quality. The longer period of feeding the soy oil enriched feed led to significant increase in polyunsaturated fatty acids. According to the findings, adding the soy oil into the feed will have no effect at all if done short time before the slaughter.

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Diploma thesis deals with the problem of observation of controlled and spontaneous fermentation influence on the organic acids content in species of wine (Ruland blue) originated in subregion of Velké Pavlovice. Initial conditions of analysis (introduced in [41] and in materials concerning chromatographic column) were changed during lasting of experiment in such manner to get the most precise analysis of the wine sample. Enzyme Rapidase Excolor was added in the beginning of both types of fermentation plus yeasts were added at the controlled fermentation. Analysis of four organic acids was done; these were tartaric, malic, lactic and citric acid. High performance liquid chromatography (HPLC) with UV detection method was used to determine concentration of each acid. Wine was processed by two technological methods – by spontaneous and controlled fermentation. Each of the process differed in the organic acids content. Concentration of tartaric acid varied from 1,63 g/l to 6,43 g/l during spontaneous fermentation process. Decrease was caused by biological processes taking place. Concentration of citric acid was not almost influenced by the process of fermentation. Due to malolactic fermentation being in progress, decrease in malic acid concentration (from 6 g/l to 1,87 g/l) and increase in lactic acid concentration was observed. Concentration of tartaric acid varies as well during controlled fermentation. Biggest increase in concentration was observed at hour 214 of the experiment when the process of fermentation was supported by addition of lactic bacteria. Due to malolactic fermentation being in progress, decrease of malic acid concentration and increase of lactic acid concentration was observed similar to simultaneous fermentation. Concentration of citric acid was constant during controlled fermentation. Experiment proved that there is higher content of observed organic acids during controlled fermentation than during processes of spontaneous fermentation.

The thesis focuses on the technology and process of producing oils from seeds of lesser known fruit species (hazel, royal walnut, black and red currant, rose hip, almond, plum, apricot and peach). It has been found that the Soxhlet method is more efficient in terms of oil yield (hazel 68% / walnut 66% / peach 44% / plum 36% / apricot 31% / currant 14% / rose 9%) than cold pressing by a screw press (hazel 62.7% / walnut 54.4% / almond 43% / plum 35% / apricot 28% / peach 27% / rose 5% / currant 2%). (GC method) The most represented fatty acids in all oils are oleic acid (18,54 - 85,77%), linoleic acid (8,13 - 59,46%) and palmitic acid (3,75 - 6, 76%). (CHASO method) Detection of minerals (C, H, N, O, S) with the highest content of C (67.4 - 85.3%)> H (10.3 - 13.5%)> O (1.5 - 22.4%)> N 0.04-0.4%). The content of elements (Fe, Ca, Cu and Mg) was found below the detection limit (ETA-AAS).

The diploma thesis deals with methods of assessing the quality of selected vegetable oils exposed to different thermal and light conditions for a set period of time. In the practical part, the quality and stability of oils is evaluated by the colour of the oils using the spectrophotometry method, content of fatty acids by the acid value and the determination of the fatty acids is assessed by the gas chromatography method. The results show that the stability of vegetable oils is most affected by exposure to the light at the temperature of 22°C in a translucent packaging. The results of spectrophotometric colour measurements revealed changes in L*, a* b*, C* and h* over a period of time, and the values varied when exposed to different storage conditions as well. The acid value has changed significantly over the course of storage in all the oils. The content of fatty acid varied during storing but was not affected by different storage conditions.

This diploma thesis is focused on the study of dissociation behaviour of natural biocolloids, namely humic acids and fulvic acids. Humic and fulvic acids are natural, heterogeneous, high molecular weight substances which behave as weakly acidic polyelectrolytes and they have complex not exactly described structure. They are formed by biochemical transformations of organic residues (mainly plants). They are part of the soil, water, peat, sediments and coal. Solubility of humic acids is affected by pH value. The higher the pH value is the higher the solubility is. Fulvic acids are soluble in whole range of pH values. The aim of this diploma thesis is to determine the dissociation constant for the five kinds of humic acids and four kinds of fulvic acids, which have been isolated from various natural sources. These samples were purchased from IHSS. Dissociation constants were determined by the conductometric method and a combination of measurment pH and the content of acidic functional groups in Na2SO4. UV-VIS spectrophotometry method was used to characterize the quality of humic acids and fulvic acids.