National Repository of Grey Literature 364 records found  1 - 10nextend  jump to record: Search took 0.05 seconds. 
Foodborne Staphylococcus Aureus: Identification and Enterotoxin Production in Milk and Cheese.
Hrušková, Vendula ; Španová, Alena (referee) ; Kmet,, Vladimír (referee) ; Kaclíková, Eva (advisor)
Onemocnění z potravin (alimentární onemocnění) vyvolaná bakteriemi jsou stále aktuálním tématem v celosvětovém měřítku. Abychom zajistili výrobu zdravotně nezávadných potravin, je potřeba nových poznatků o virulenci patogenů, které by doplnily již známé skutečnosti o jejich růstu a přeživání v potravinách. Také potřebujeme vyvíjet rychlé a citlivé metody na detekci těchto patogenů. Dizertační práce popisuje metodu na detekci S. aureus v potravinách, která je založená na PCR v reálném čase ve spojení s namnožením v selektivním médium. Dále pojednává o vlivu environmentálních faktorů na růst S. aureus a tvorbu enterotoxinů v mléce a sýrech. Vyvinuli jsme rychlou a citlivou metodu na detekci S. aureus v potravinách s použitím selektivního namnožení a PCR v reálném čase. Nově vyvinutá metoda umožnila detekci S. aureus na druhý den od přijetí vzorku. Tato metoda může být použita jako rychlejší, citlivějsí a vysoce specifická alternativní metoda ke konvenční mikrobiologické metodě. Zkoumali jsme vliv tří různých teplot, 8°C, 12°C a 20°C na růst S. aureus a tvorbu enterotoxinu D v pasterizovaném mléce a na růst, expresi genu sed a tvorbu enterotoxinu D v tekutém médiu s extraktem z mozku a srdce (BHI). Experimenty byly prováděny v malých skleněných fermentorech po 6 dní. Genová exprese byla sledována pomocí qRT-PCR a tvorba enterotoxinu D byla měřena pomocí imunologické metody ELISA. Růstová křivka v BHI měla stejný průběh při 20°C a 12°C, ale v při 12°C začal růst se spožděním. Při 8°C nebyl pozorován žádný růst. Růst S. aureus v mléce byl ve srovnání s BHI menší. sed mRNA byla detekována při 20°C po 4 hodinách a při 12°C po 7 hodinách a produkce enterotoxinu se objevila v exponenciální fázi růstu. V mléce se produkce SED při 20°C a při 12°C objevila dříve, ale celkové množství vyprodukovaného SED bylo nižší než v BHI. Při 8°C nebyla pozorována žádná produkce SED stejně jako v BHI. Dále byl zkoumán společný vliv nízké teploty 12°C a přítomnosti kompetitivní doprovodné mikroflóry pocházející ze surového mléka na růst S. aureus a produkci enterotoxinu v pasterizovaném mléce. Byl pozorován inhibiční účinek na růst a produkci enterotoxinů a vliv kompetice byl výraznější než vliv nízké teploty. Produkce enterotoxinu byla nízká a odpovídala růstu. Snížením množství doprovodné mikroflóry a zvýšením inokula došlo pouze k nepatrnému zvýšení produkce enterotoxinu. V další fázi byly dva různé typy sýrů zaočkovány S. aureus za účelem simulace sekundární kontaminace při výrobě sýrů. Vzorky byly odebírány v průběhu 4 týdnů. Kritické faktory jako jsou kompetitivní mikrofóra nebo pH, které jsou zodpovědné za regulaci virulence S. aureus byly sledovány. Snažili jsem se rozlišit situace při kterých: (i) není pozorován růst, ale objevuje se produkce enterotoxinu a (ii) dochází k růstu ale bez produkce enterotoxinu.
Stables with Milking House
Lenoch, Petr ; Hovořák, Dalibor (referee) ; Hlavačka, Tomáš (advisor)
Master’s thesis deals with a project documentation of a farming building. It is situated in agrarian farm in Horní Kalná in Královehradecký kraj. There will be 340 cows. Stable will be connect with milking house by connecting tunnel. Head mission is with simply solving and with useing high technology create very good conditions for stay of animals (welfare).
Monitoring of Phytoestrogens Expression to the Milk and Milk Products
Watzková, Jarmila ; Rittich, Bohuslav (referee) ; Doležal, Petr (referee) ; Omelková, Jiřina (advisor)
Phytoestrogens are very intensively studied in recent years because they show different pharmacological effects on human health. For example, it was demonstrated that phytoestrogens reduce the risk of certain cancers (breast, prostate or colon), act as antioxidants in the body and affect the activity of certain enzymes. In addition, also it was demonstrated number of positive effects of soybean phytoestrogens on the health status of women in the menopause, such as reducing the risk of atherosclerotic cardiovascular disease or osteoporosis. Various technologically processed soy beans are important part of the feed rations mainly for high-lactating dairy cows, because they are a valuable source of the energy and high-quality protein, despite their negative effect on reproductive performance. Phytoestrogens consumed from the feed rations are hydrolyzed in the rumen of dairy cow and together with their metabolites are absorbed in the small intestine into the blood. They can be excreted from the body in urine or milk. From this perspective, cow's milk may become a source of phytoestrogens substances, especially equol in the human nutrition. On the other hand, some research results suggest possible potential risks associated with phytoestrogens intake in the diet on human health. At the some age (infants and young children) and group (vegetarians) categories may be dietary intake of phytoestrogens undiserable. According to most experts, a beneficial effect on human health prevail the potential risks. However, the risks associated with phytoestrogens intake in food can not be ignored and therefore phytoestrogens are still actual problem in the field of scientific research.
Comparison of aroma profile of goat vs. cow milk
Pospíchalová, Alžběta ; Saláková,, Alena (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the comparison of aroma compounds in goat and cow milk. The content of aroma active substances in samples of goat and cow milk, which were analyzed by HS-SPME-GC-MS method, is monitored. In the theoretical part, milk is characterized, its formation in the dairy mammary gland is described, its composition including an overview of aromatic active substances, physical and chemical as well as its sensory properties, milk defects and differences between cow's and goat's milk are described. Further, gas chromatography in combination with solid phase microextraction technique in tandem with mass spectrometry is described. In the experimental part, 13 samples of goat and 8 samples of cow milk were subjected to HS-SPME-GC-MS analysis. Samples were analyzed fresh and after heat treatment. Altogether, 78 volatile substances were identified in the samples. Ketones were the most numerous, aldehydes, alcohols and carboxylic acids were the most abundant chemical groups. There were differences between samples in number as well as in content of the identified compounds, 64 in goat milk and 48 in the cow milk.
Cheese curd parameters influence to selected economic factors of production of cheese with white fungus
Pavlíčková, Žaneta ; Zemanová, Jana (referee) ; Babák, Libor (advisor)
The theme of this diploma thesis is the monitoring of influences on economic aspect of the production of the blue cheese "Hermelín" in the company Pribina. The objective was to specify the dependencies of the deviations of the features of productive cow's milk and of cheese curd made from it and their economics impacts. For this purpose, the analyses of curd grain, whey and cheeses just formed were executed. The samples were taken and analyzed during the manufacturing of cheeses in the factory. Another goal was to try to design a quick operational method for measuring the firmness of curd grain, which is a factor theoretically dependent on renneting qualities of milk and indicating losses of valuable components from cheese curd to whey. The firmness of grain along with these losses may cause negative deviations from required standard of final products, especially at parametres needed for entry of cheeses on sale, such as total solids, weight or content of fat. Concerning productive pasteurize milk, the most attention was focused on the milk coagulation time and its influence on successive phases of manufacturing and on final product. Milk coagulation time is an essential technological quality of milk and it is participant on quantitative and qualitative production of cheese factory. It has been proved that milk coagulation time is notably affected by its titrating acidity, statistic analyse found this influence as very statistically significant (P
Milk and dairy products and their importance in nutrition
Šubertová, Hana ; Vítová, Eva (referee) ; Omelková, Jiřina (advisor)
This bachelor thesis is engaged in the analysis of the composition of the milk, its creation, origin and source and furthermore it is engaged in the evaluation of the beneficial and harmful properties of milk. Another aspect of this thesis is reasoning about why we should consume milk and whether it is even beneficial to health. In the following part of this work, the literature review is created about about how milk and different products affect human nutrition and the thesis is studying the problematics of milk consumption. The next part of my thesis describes the course of "milk route", which explains what is happening to milk as a raw material, then the technology of production and processing of milk, milk products and semi-finished products and also contains the comparison of my measured data with the standardized data, or the data on the packaging.
Analysis of selected elements in milk by ICP-OES
Sekaninová, Renáta ; Vespalcová, Milena (referee) ; Diviš, Pavel (advisor)
This Master's thesis is dealing with elementary analysis of milk. Theoretical part describes general characteristics, terminology with basic legislature and classification of milk. Large part is focused on chemical composition, especially on description of mineral substances selected for analysis in experimental part of this thesis. Choices of elementary analysis and preparation of samples for ICP-OES method conducted by other authors are also mentioned. Specification of emission spectrometry with inductively coupled plasma is crucial, a technique used for purposes of this dissertation. Experimental part deals with preparation of samples, approach of analysis and processing of measured results. The aim of this part is to compare concentration of analyzed elements in different kinds of milk. Samples from 15 different kinds of milk were used for analysis, which were determined by ICP-OES method. Results were compared to each other in discussion as well as with results from other authors.
Determination of microelements by ICP-OES after extraction by DGT technique
Habartová, Aneta ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This thesis is focused on determination of microelements (Cd, Co, Cu, Fe, Mn, Ni, Pb a Zn) in milk by optical emission spectrometry with inductively coupled plasma (ICP-OES) after extraction by Diffusion Gradients in Thin films technique (DGT) containing Chelex 100 resin gel and agarose diffusion gel. The optimalization of DGT in model metal solutions was verified by recommended basic tests. The performance of the DGT technique in the diluted milk matrix was verified. By DGT technique was determined only Zn in real milk matrix with concentration 3,74 ± 0,02 mg/l. The other microelements in the prepared eluate were at or below the limit of detection of the instrumental method. The obtained results were compared with the analysis of milk after microwave digestion by ICP-OES. However, these results were below the detection limit of the device too, only Zn with concentration 3,91 ± 0,16 mg/l was measured. For the future analysis of the selected microelements in milk by DGT technique, further optimization of the preconcentration technique is required, or use of a more sensitive instrumental method.
Nutritional composition of different type of milk
Viznerová, Veronika ; Punčochářová, Lenka (referee) ; Diviš, Pavel (advisor)
The aim of this bachelor’s thesis was to compare selected methods of milk treatment for elementary analysis using the ICP-OES technique. Certified reference material ERM®-BD150 was used to validate the method, which was treated by mineralization, the addition of reagents and dispersion. The highest calcium yield during validation was determined to be 90,6 ± 8,6 % with the addition of Triton X-100 reagent. In the potassium analysis, the highest yield was determined to be 89,5 ± 5,2 % by wet decomposition. The highest yield of magnesium was determined to be 120,1 ± 1,1 % after microwave decomposition. Furthermore, the highest yield of sodium was determined to be 104,4 ± 4,8 % by wet decomposition and the highest yield of phosphorus was determined to be 98,6 ± 4,5 %. Based on the validation results, suitable methods were selected for the analysis of real milk samples (wet decomposition, acid dispersion, addition of Triton X-100 reagent). Samples of fresh cow's, goat's and sheep's milk from domestic breeding were used for the analysis. The highest concentrations of most elements were determined in goat 's milk, namely calcium to 1 733 ± 126 mg.kg-1, potassium to 1 840 ± 39 mg.kg-1, magnesium to 252 ± 77 mg.kg-1, copper to 1,41 ± 0,56 mg.kg-1, manganese to 0,54 ± 0,26 mg.kg-1 and zinc to 7,98 ± 1,33 mg.kg-1. The highest concentrations of sodium in sheep's milk were set at 515 ± 90 mg.kg-1, phosphorus at 1 440 ± 100 mg.kg-1 and zinc at 7,98 ± 1,33 mg.kg-1. The most iron was found in cow's milk, namely 5,27 ± 1,59 mg.kg-1. For ICP-OES analysis, the use of an acid dispersion appears to be the best method of sample preparation, as the concentrations of the measured elements were the highest. However, only macroelements and zinc were measured reliably. For the determination of other biogenic elements, it would be more appropriate to choose a more sensitive technique or preconcentration of the analyte in the sample.
Vliv věku při prvním otelení na mléčnou užitkovost holštýnských dojnic v konkrétním podniku
Landová, Valentýna
The bachelor thesis dealt with the effect of age at first calving of Holstein dairy cows on their subsequent milk yield. In the literature section, the basic characteristics of Holstein cattle, milk yield, milk composition and the influences on milk yield were described. In addition, fertility and reproduction of cows were defined in more detail. The practical part took place on a farm located in the Central Bohemia region. A total of 52 Holstein dairy cows were included in the evaluation. The selected cows were divided into four groups according to their age at first calving (calved up to 21 months, 22-23 months, 24-25 months and over 26 months). The data from the performance monitoring of Holstein cows in their first lactation were used in this study. Milk performance parameters monitored included milk yield, fat, protein, lactose, urea and somatic cell count. The effect of lactation stage on the listed milk parameters was also monitored. The lowest milk production was achieved by cows calving at 21 months of age (29.74 kg milk). On the other hand, the highest milk yield was obtained by cows calved at the age of 26 months and above (33.52 kg milk). This difference was found to be statistically significant (p<0.05). Furthermore, a sta-tistically significant difference (p<0.05) was found between the average milk yield of cows calved at less than 21 months of age and those calved at 24-25 months of age. The effect of age at first calving did not have a statistically significant difference (p>0.05) on the other observed milk contents.

National Repository of Grey Literature : 364 records found   1 - 10nextend  jump to record:
Interested in being notified about new results for this query?
Subscribe to the RSS feed.