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The diploma thesis is concerned with the quality of UHT milk in the Czech republic and changing its properties during cold storage. The first part describes the composition of milk and the various steps of the manufacturing process of milk treated by high temperature heating. It is further elaborated the issue of nutritional and sensory changes after heat treatment. The second part focuses on the research of 35 samples of milk with different fat content UHT-treated by heating purchased in the Czech markets. We bought two packs from each sample. The content of some ingredients (fat, protein) listed on the packaging were experimentally controlled for all samples. A titratable acidity and active acidity was measured and the milk was analysed for sensory and microbiological quality. The samples were stored in the refrigerator. After the shelf life the sensory and microbiological quality was tested. The titratable and active acidity was checked again. The results were statistically analyzed by paired t-test and compared with results of other authors. It showed good quality UHT milk placed on the Czech market.

The evaluation of changes during fermentation of heat-modified milk in connection with different fermentation temperatures was main goal of this thesis. Titrable acidity, active acidity and growth dynamics of bacteria strains - Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus were observed during fermentation process.

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The theme of this thesis is The use of bioactive compounds in order to prolong durability of dairy products. In the theoretical part, the importance, presence and influence of bioactive compounds are discussed. Also described are the individual dairy products, the use of fermentation in order to prolong durability of products and the use of lactic acid bacteria during process of production of fermented dairy products. Subsequently, the discussion focuses on the influence of bioactive compounds in dairy products on personal health. The aim of the practical part is to examine the influence of adding herbal essential oils and infusions into the sweet whey. The investigation concentrated on whether there was any influence on the chemical properties of whey and its durability.

The purpose of diploma thesis was evaluate the effect of milk production an the season on the quality colostrum Czech fleckvieh cattle in a selected breeding. Between monitored parameters were included solids, active acidity, density, imunoglobulins content and refraction. Literary review was processed to the given problem. Viewed samples came from the farm Agrodružstvo Tištín. Samples were taken during the whole year (from 17. 4. 2014 to 18. 1. 2015). In this period has been taken 39 samples of colostrum, from selected cows. These cows were all on the second lactation. The measured values were statistically processed. The results indicate, that cows with high milk production have better quality of colostrum. Seasons affected the quality of colostrum. The cows, who gave birth in the autumn and winter, had colostrum quality. We found, that healthy cows had in colostrum more immunoglobulins and solids, during the assessing the health condition.

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.

This thesis focused on the factors influencing the ripening of cheese , especially the first phase. The literature review was prepared during maturation of cheese , which is a comprehensive summary of the changes caused syřidlovými enzymes and enzymatic activity of cultures in which the cheese gets the typical appearance, texture, flavor and composition

The object of the dissertation was the monitoring of the quantity of the yogurt culture microbes Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus in selected yogurts after the end of the mature process and the consideration of the observed values with the requirements of the legislation. The literary search mentions the fermented dairy products and their classification, the characterization of individual types of lactic fermentation microbes and also the pure milk cultures used for the production of soured dairy products are not left out. The experimental part deals with the evaluation of microbiological analysis and the acidity of selected yogurts according to the influence of the producer and the storage life. The observed results showed, that the legislative requirement for the quantity of live microbes has been kept not only during the prescribed best-before period, but also during the complete experiment, it means also on the 56th day of the storage.

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