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DNA extraction from cheeses for polymerase chain reaction analysis
Mohelský, Tomáš ; Rittich, Bohuslav (referee) ; Španová, Alena (advisor)
This work was focused on DNA isolation from cheeses for the use in polymerase chain reaction. First, there was optimised the procedure of homogenisation of different types of cheeses from commercial sources, cell lysis and DNA isolation. DNA was isolated using magnetic microspheres and phenol extraction. It was shown that the DNA was amplified in PCR for domain Bacteria after dilution. Next, there was optimised the procedure of DNA isolation from fresh cheeses and from contaminated fresh cheeses and their pickles. DNA from all samples was amplified in PCR. The presence of DNA of domain Bacteria and yeast DNA was demonstrated. In the last part of the work, there were optimised the preparation of PCR mixtures and bacterial DNA amplification in PCR with primers with clamp (F357-GC and R518). Synthetized PCR products were analysed using DGGE. It was shown that amplicons of DNA isolated from cheeses and pickles differ in positions and numbers. Larger number of bands of different intensities was detected after amplification of DNA isolated from contaminated pickles.
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Mikrobiologie čerstvých a polotvrdých sýrů – změny v počtech významných skupin mikroorganismů v průběhu výroby a skladování.
Vítová, Jana
The aim of the thesis was to find out whether the numbers of important groups of microorganisms in fresh and semi-hard cheeses change during storage. Changes in the number of microorganisms were detected by microbiological analysis, where significant groups of microorganisms were determined. The total number of microorganisms, psychrotrophic microorganisms, coliforms including Escherichia coli, lactic acid bacteria and micromycetes including yeasts and molds were detected. The microorganisms were detected in fresh cheeses packed in boxes, vacuum packed stored for 14 days and stored for 21 days. The fresh cheeses were produced in the dairy manufactory of the Faculty of AgriSciences at Mendel University and contained four different concentrations of cream starter. For the semi-hard cheeses microbiological analysis was carried out on delivery of the cheeses to the laboratory and subsequently at an interval of either 14 days or 8 weeks. The semi-hard cheeses were obtained from the market. Very low numbers of coliforms and moulds were detected in packaged fresg cheeses. On the other hand, due to the longer storage time, there was a significant decrease in lactic acid bacteria. Longer storage period resulted in higher detection of yeast and psychrotrophic microorganisms. As for semi-hard cheeses that were analysed after 8 weeks, there was a decrease in the total number of microorganisms and lactic acid bacteria. For semi-hard cheeses analysed after 14 days, higher total numbers of microorganisms, psychrotrophic bacteria and moulds were detected. No coliforms were detected in any of the semi-hard cheeses, including Escherichia coli. The results of the work showed that vacuum packaging of fresh cheeses can extend their shelf life. However, longer storage times reduce lactic acid bacteria.
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Technologie výroby čerstvých sýrů v závislosti na použitých surovinách a podmínkách výroby
Koudelková, Jana
In the theoretical part, this diploma thesis first deals with the definition of fresh cheeses and also describes the history of cheeses in general. Subsequently, cheeses are classified based on several factors and the basic representatives of fresh cheeses are described here. It describes what raw materials are necessary for the production of fresh cheese, and how the process of their creation looks step by step. The work contains information on the basic sensory properties of fresh cheeses and possible defects that may occur in fresh cheeses. The last part of the theoretical work is focused on potential factors in the production of fresh cheese that could affect the quality and taste of the final product, including the possibilities of its quality control. In the experimental part of the thesis, raw materials and procedures for the production of fresh cheese were first selected, and then the production of fresh cheese itself took place. After production, the basic chemical and sensory properties of the manufactured products were determined. The results showed that the produced fresh cheeses corresponded chemically to the general values and the spices used significantly influenced parameters such as the taste and aroma of the cheese. Provençal spices were used for flavoring; paprika and pepper; wild garlic and dill; Italian herbs, which in the end were evaluated as the best option for flavoring cheeses. The obtained results were processed into graphs and evaluated statistics.
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Způsoby prodloužení údržnosti mléčných výrobků
Piskačová, Martina
This thesis on a Method for extending the shelf-life of dairy products in its theoretical part with milk and milk products, in special chapters separately with fresh cheese - their general process of production and possible defects. Furthermore, the theoretical part deals with the reasons for spoilage of dairy products, due to the external environment on microorganisms. These include in particular the temperature, pH and water activity. The other chapters are focused on different basic methods for extending shelf-life, which are often used in dairying. These include antimicrobial agents, lactic acid bacteria. Lactic acid bacteria is devoted to a separate subhead with protective lactic acid bacteria. The last part of the theoretical thesis is focused on hygiene, which to make cheese inseparable. The practical part of this study looked at the effects of protective cultures added to fresh cheeses. In dairy pilot plant were produced four kinds of cheese - three different types of protective cultures, one with classic cream culture. Samples were always salted and unsalted. All samples were then evaluated by chemical and microbiological analysis to determine the effect on shelf life.
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DNA extraction from cheeses for polymerase chain reaction analysis
Mohelský, Tomáš ; Rittich, Bohuslav (referee) ; Španová, Alena (advisor)
This work was focused on DNA isolation from cheeses for the use in polymerase chain reaction. First, there was optimised the procedure of homogenisation of different types of cheeses from commercial sources, cell lysis and DNA isolation. DNA was isolated using magnetic microspheres and phenol extraction. It was shown that the DNA was amplified in PCR for domain Bacteria after dilution. Next, there was optimised the procedure of DNA isolation from fresh cheeses and from contaminated fresh cheeses and their pickles. DNA from all samples was amplified in PCR. The presence of DNA of domain Bacteria and yeast DNA was demonstrated. In the last part of the work, there were optimised the preparation of PCR mixtures and bacterial DNA amplification in PCR with primers with clamp (F357-GC and R518). Synthetized PCR products were analysed using DGGE. It was shown that amplicons of DNA isolated from cheeses and pickles differ in positions and numbers. Larger number of bands of different intensities was detected after amplification of DNA isolated from contaminated pickles.
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Processing of fresh cheese depending on selected factors
KOŘÁN, Jakub
Bachelor thesis is focused on processing of fresh cheese depending on selected factors. The cheeses were made in laboratory for this purpose and some factors influencing cheese making were tested. The performed experiments show the effect on cheese yield, milk composition, good manufacturing process and different fermentation temperature. This influence is particularly evident in the overall yield of cheese curd, weight of curd, release rate of whey and pH of curd. The performed experiments can lead to conclusion that each of these factors affects the overall quality of the curd. From the perspective of producers of fresh cheeses is important to monitor these factors as compliance with proper procedure and avoiding the factors reducing yield, will have a positive economic impact.
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