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Factors influencing the quality of red wine
Zechmeisterová, Lucie ; Vránová, Dana (referee) ; Omelková, Jiřina (advisor)
In my thesis, I focused on monitoring of microorganisms in the sample of red grape juice and on the interactions between yeasts, bacteria and filamentous fungi. Three different media were applied for the cultivation of microorganisms; firstly for monitoring of total volume of microorganisms, secondly for yeasts and third time for lactic acid bacteria. The indirect method was used for the determination of the amount of viable cells. This method consists in enumerating of visible macroscopic colonies grown up on agar plates. When the cells grew up, the forms of colonies were analyzed visually and the morphology of microorganisms was detected microscopically. The operating time of enzymes in grape juice in the production of red wine was monitored after application of commercial enzymatic preparation. The enzym action in grape juice was observed on the basis of the process of degradation of high – molecular substrate by enzymes through the use of Ubbelohd´s viscometer. The research findings provided a lot of knowledge about the occurance of microflora in the process of production of red wine. The commercial preparations added to grape juice played a significant role.
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Quality characteristics of beef during storage
JANOUŠKOVÁ, Kateřina
The topic of this work is to verify the effect of different treatments of beef after slaughter on quality characteristics, aerobic plate count on the surface of meat during maturation and sensory properties of matured meat before and after heat treatment. The literature review describes the quality characteristics of meat, the effects on quality, the maturing process and the methods of treatment of meat after slaughter. The practical part of the work consisted of treating meat after slaughter with lactic acid, lactic acid + onion peel extract and pure onion peel extract. The next part consisted of measuring the pH and the aerobic plate count during the dry maturation of beef quarters and after the wet maturation in the vacuum bags, determine the composition of the meat, the dripping of the water, the color and the sensory evaluation of the meat. The obtained values were statistically evaluated.
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Influence of dairy cow pasture on microbial contamination of raw cow milk
KOŠTELOVÁ, Lucie
The goal of the graduation theses was a comparsion of the hygienic quality of raw cow΄s milk, it was expressed by the value of total bacterial count (TBC) in breeds of milking cows using summer pasture (3 breeds) in comparsion with breeds without using the summer pasture. The breeds differed in technology of stabling and milking procedures, using predipping and size of the herd. During monitoring (from January till December 2007) it was discovered that the breeds using the summer pasture had lower average values of TBC (11,04.103.ml-1) in comparsion with the breeds without using the summer pasture (12,76.103.ml-1), the difference wasn´t statistically significant on the level of significance P < 0,05. Within the frame of breeds with pasture system was detected the lower microbiological contamination of milk in pasture period (TBC = 7,92.103.ml-1) in comparsion to non {--} pasture period (TBC = 13,38.103.ml-1). It´s possible to state that the pasture has positive effect on lowering of milk´s microbial contamination.
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Influence of cold chain interruption on microorganisms growth in milk
BEEROVÁ, Michaela
Raw milk is one of the most monitored product not only in terms of microbial, but also in terms of technology, chemistry and sensory. The aim of the thesis was the examination of the influence of cold chain interruptions on dynamic of total bacteria count (TBC) in raw cow milk. The results show that the temperature and time have a significant impact on TBC. The samples stored during the first three hours of experiment at 15 °C showed (in time 0 - 27 hours) a continuous growth with changing dynamic (5.13, 6.66, resp. log CFU/ml). The samples stored at 30 °C showed a significant increase, however there was a decrease between an hour of 25th and 26th (6.88, 6.69, resp. log CFU/ml). An hour later another increase was found (to 7.37 log CFU/ml). The samples stored at 6 °C showed the lowest values of TBC, although an increase was found after 24 hours (5.87 log CFU/ml). The second part of the thesis was an evaluation of the questionnaire survey among people consuming raw cow milk from a vending machine. The survey showed that more than a half of respondents (88%) interrupt the cold chain for no more than an hour. Then it was found that 75% of respondents do not overcook raw milk. The consumers appreciate the taste of raw milk (35%), freshness (19%), quality (16%), and a nutritional value (12%).
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Factors influencing the quality of red wine
Zechmeisterová, Lucie ; Vránová, Dana (referee) ; Omelková, Jiřina (advisor)
In my thesis, I focused on monitoring of microorganisms in the sample of red grape juice and on the interactions between yeasts, bacteria and filamentous fungi. Three different media were applied for the cultivation of microorganisms; firstly for monitoring of total volume of microorganisms, secondly for yeasts and third time for lactic acid bacteria. The indirect method was used for the determination of the amount of viable cells. This method consists in enumerating of visible macroscopic colonies grown up on agar plates. When the cells grew up, the forms of colonies were analyzed visually and the morphology of microorganisms was detected microscopically. The operating time of enzymes in grape juice in the production of red wine was monitored after application of commercial enzymatic preparation. The enzym action in grape juice was observed on the basis of the process of degradation of high – molecular substrate by enzymes through the use of Ubbelohd´s viscometer. The research findings provided a lot of knowledge about the occurance of microflora in the process of production of red wine. The commercial preparations added to grape juice played a significant role.
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Microbial quality of cow´s raw milk
HAVRÁNKOVÁ, Iveta
The microbiological quality of raw milk from the perspective of the health of dairy products is one of the most important features. The amount of microorganisms is influenced by storage temperature and time of milk. In the thesis was observed dynamics of total bacteria count (TBC) in raw milk depending on the selected factors (months, seasons, point of collection, the length of storage). To life of microorganisms contributes warm weather. The largest increase in TBC was observed in the months of April and May to 108 thousand /1 Ml. It is necessary to place great emphasis on rapid cooling of milk (max 150 min.) to the desired temperature (8 °C). Increase TBC could be caused by long transportation time of sampling raw milk from a milk vending machine to evaluate the quality and microbiological indicators. In the second part of the thesis are compares the quality and microbiological characteristics of raw milk from selected milk vending machines. When evaluating the samples taken from the farm, average values of TBC were higher (43 thousand/ml) compared to samples collected from the milk vending machines (6 thousand/ml). Reason of higher values from farms could be caused by poor hygiene of the milk and his secondary contaminations. In contrast, the average results from samples taken from the milk vending machines were more than excellent. That´s shows tight control of cooling milk during transportation from the farm to the milk vending machine. Next reason better results is right cooling and to maintain a constant temperature in the grades (from 0.5 to 1 °C). That´s temperature, which prevents the growth of microorganisms.
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