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"Změny mikrobiologické jakosti ""čerstvých"" těstovin v průběhu skladování"
Vyhňáková, Michaela
The master‘s thesis is focused on changes in the microbiological quality of "fresh" pasta during storage. Fresh pasta is characterized by a high moisture content (minimum 24 weight percent), which allows microbiological growth and considerably limits the shelf life, which is set at a maximum of 14 days from the date of production. The following parameters were monitored for each type of fresh pasta: total number of microorganisms, fungi and yeasts, Escherichia coli, Staphylococcus aureus and Bacillus cereus. Samples of fresh pasta were always taken immediately after production, during storage and at the end of the shelf life, ie on the 1st, 9th and 13th day of storage. The pasta was divided into five groups: non-flavored pasta, flavored pasta, potato pasta, meat stuffed pasta and cheese stuffed pasta. During the storage of fresh pasta, the values of individual monitored microbiological indicators changed depending on the type of pasta. In some cases, there has been an increase in the number of microorganisms monitored, for example in non-flavored pasta there has been an increase in the number of molds and yeasts between the 1st and 9th day of storage. In other cases, on the other hand, a decrease was recorded, as in the case of non-flavored pasta, when the content of Staphylococcus aureus was reduced. In some cases, the numbers of microorganisms monitored did not change, for example, in the non-flavored pasta, the total number of microorganisms and the number of E. coli did not change during storage. Furthermore, the microbiological quality of flavored and non-flavored pasta was compared, and a higher (p <0.05) incidence of the total number of microorganisms in flavored pasta was found. When comparing pasta stuffed with meat and pasta stuffed with cheese, no statistically significant differences (p> 0.05) were recorded in the numbers of monitored microorganisms.
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Vliv fermentace a skladování na jakostní parametry fermentovaných mléčných výrobků
Šín, Kamil
This diploma thesis deals with fermented dairy products. The theoretical part of the work deals with the legislative division of fermented dairy products, describes the raw materials needed for their production, focuses on microorganisms enabling fermentation and production technologies of various types of fermented dairy products. In the experimental part, an experimental production of yoghurts with different fat content was performed using different heat treatments. Analyzes were performed to determine the chemical composition of the products and the presence of microorganisms in the products during the three weeks of storage. After obtaining the data, a statistical evaluation of the influence of different temperatures and storage on the quality parameters of experimental products was performed. The values of the total count of microorganisms did not change significantly during storage, as well as the numbers of lactic acid bacteria were balanced, with a slight decrease in the numbers in the second week. Psychrotrophic microorganisms were recorded at a stable value, with the exception of two samples at week 3. Yeast also recorded the highest increase in the second week and fungi in the third week. No enterococci or coliform bacteria were detected in the samples at all times. The measured pH of the samples showed a stable decreasing tendency together with an increase in the titratable acidity values due to the post-acidification ability of the bacteria. The parameters fat content, protein content and total solids content did not change during the storage period, differences can be observed in protein content and total solids content depending on heat treatment
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Využití bylinných silic při konzervaci potravin
Vlčková, Jana
The diploma thesis „The use of herbal essential oils in food preservation“ deals with natural substances that arise as secondary metabolites of plants – essential oils. Essential oils have various biological properties that can be used in food preservation. The first part summarizes the theoretical knowledge about the importance of food preservation and also describes the factors and methods of preservation that can affect or prevent the occurrence of microorganisms in food. Further informations describe the importance of essential oils in the plants and methods of obtaining them. The chemical composition of essential oils and their biological activity are also described here. The second part deals with the practical analysis of zucchini chutney with added essential oils, including microbiological and sensory analysis and also measuring pH of the product. Essential oils have been shown to have preservative effects. According to sensory analysis, respondents preferred samples with added lemon essential oil at lower and higher concentration and also samples with added dill essential oil at lower concentration the most.
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Změny v množství významných skupin mikroorganismů v průběhu skladování sýrů
Bažantová, Bára
The diploma thesis charakterizes cheeses, describes the requirements for the milk used for cheese production, describes technological operations of their production and is focused mainly on the microbiological composition of fresh cheeses. Cheese is a dairy product made by fementing lactose by lactic acid bacteria. Therefore, it is common for cheeses to contain a high number of total count of microorganisms and lactic acid bacteria. The practival part is focused on determining and evaluating the occurrence of selected groups of microorganisms and their change during storage in fresh cheeses produced in the dairy pilot plant of the Institute of Food Technology and cheeses purchased in the sales network. The influence of storage time, producer and type of milk used for cheese production was statistically evaluated. Overall, the number of microorganisms did not differ during the storage, with the exception of micromycetes. Samples purchased from the retail network were more contaminated. The cheeses from the milk of small ruminants had a higher number of lactic acid bacteria and of contaminating psychrotrophic microorganisms.
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Study of the possibilities of using superabsorbent additives in concrete
Kubíček, Matyáš ; Jančář,, Josef (referee) ; Hela, Rudolf (advisor)
This bachelor's thesis deals with the study of self-healing of cracks in cement composites. In the theoretical part, four chapters describe the mechanisms that influence the durability of concrete or can extend it. In the first chapter, I deal with concrete additives that affect the water consumption in concrete. This chapter is focused on plasticizers. In the second chapter, I deal with the treatment of concrete, how long to treat it and what are the ways of treating it. In the third chapter, I write about rehabilitation, about the additional life extension of building structures using various technologies and mechanisms. The fourth and last chapter of the theoretical part is the most comprehensive and discusses the self-healing mechanisms of concrete with the help of several types of microorganisms that heal cracks with their products. Then about calcium lactates, which are often combined with microorganisms to improve the effects of self-healing. About non-metallic polymer fibers, both natural and synthetically produced, added to concrete to improve properties. In the last subsections, I mention the use of colloidal SiO2 solutions and especially superabsorbent polymers, the investigation of which plays a significant role in this thesis. In the experimental part, the influence of the amount of superabsorbent additive in concrete on the ability of self-healing is investigated. The ability to heal cracks, which will be artificially created after mixing the concrete mixture, when placing the concrete in the forms, is investigated. Furthermore, the influence of the effect of the superabsorbent additive in different deposits will be investigated. Subsequently, the samples will be tested for tensile strength after bending and compressive strength.
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Environmental monitoring for production quality assurance
Minářová, Klára ; Köbölová, Klaudia (referee) ; Řezáčová, Veronika (advisor)
This bachelor's thesis deals with the topic of environmental monitoring to ensure production quality. Specifically, the attention was paid to the monitoring of the presence and development of the number of microorganisms in the air and on work surfaces in specific production areas at regular intervals. The number of microorganisms in the air was determined by the method for determining the microbiological burden of the air, and the concentration of microorganisms on the surface was determined by the method of imprinting the tested area on an agar plate with subsequent cultivation and counting the bacterial colonies according to the internal regulations. Monitoring is carried out by the control microbiological laboratory, which falls under the quality department of the given manufacturing company. The basis for the preparation of this bachelor's thesis was obtained during my intership in the control microbiology laboratory.
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Microbial bioremediation of persistent organic pollutants
ŽÁČKOVÁ, Jana
Persistent Organic Pollutants (POPs) are one of the most significant environmental contaminants. Their common characteristics represent high toxicity and the ability to accumulate and persist in living organisms, causing serious health risks. Microbial bioremediation is an effective solution in environmental decontamination via microorganisms, which can use some pollutants as a source of carbon and energy. The bachelor's thesis aimed to (a) provide comprehensive information on POPs; (b) describe the potential for degradation or transformation of POPs via bioremediation technology; (c) characterize the most used types and specific microorganisms used for microbial bioremediation and describe the practical cases of applications of these microorganisms in the context of POPs bioremediation. The last part of the thesis discussed the negative effects of environmental pollution and the related possibilities of bioremediation applications to suppress the impacts of pollution.
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Heat effects of microbial life in soil
Drápalová, Karolína ; Kalina, Michal (referee) ; Krouská, Jitka (advisor)
This research is intended to be an application of calorimetry to the study of thermal manifestations of microbial life in soil. Although this research has slowly but steadily expanded over the past half century, many unanswered questions still remain. Calorimetry is a suitable tool for determining several parameters of soil quality. Therefore, it is a very important indicator for agriculture. Very well-known indicators used in soil research can be measured by various calorimetric methods such as differential compensation calorimetry (DSC) and thermogravimetry (TG), which are temperature scanning methods used to estimate certain properties of soil material. Calorimetry can be used to determine the activity of microbial life in the soil, which is an essential parameter for the proper functioning of the soil, i.e. for its health. Microorganisms will release a certain amount of heat, based on their metabolism, which can be boosted by adding certain nutrients. We can therefore say that the presence of microorganisms in the soil can be detected thanks to calorimetry.
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Preservative systems for natural cosmetics
Koblasová, Dana ; Veselá, Mária (referee) ; Zemanová, Jana (advisor)
The aim of this bachelor thesis is to evaluate the antimicrobial activity of naturally derived preservatives against selected microorganisms. Theoretical part is focused on description of the most used natural, naturally derived and synthetic preservatives, on the safety of preservatives and finally, the issue of contamination of cosmetic products by microorganisms. In experimental part, antimicrobial activity of 4 naturally derived preservatives was evaluated against selected microorganisms, which were bacteria Micrococcus luteus, Kocuria rosea, Bacillus cereus, Bacillus subtilis, Serratia marcescens and one yeast Candida vini. The tested preservatives were from MinaSolve company - E-LEEN Green A, which contains pentylene glycol and phenylpropanol, E-LEEN Green OR, which is composed of citrus extracts, citric acid, ascorbic acid and pentylene glycol, Green B, which contains benzoic acid, sodium benzoate and pentylene glycol and Hexam+, which is a mixture of pentylene glycol and hexamidin diisethionate. Antimicrobial activity was evaluated by agar diffusion method. The highest antimicrobial activity showed Hexam+, the lowest E-LEEN Green OR. E-LEEN Green A and Green B did not show any antimicrobial activity against any microorganism in the 1% tested concentration. The measured values of the inhibition zones show that the most resistant microorganisms from all the tested in this thesis are Bacillus cereus and Bacillus subtilis and the least resistant are Micrococcus luteus and Kocuria rosea.
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Microbiology of raw milk and milk after treatment
Pláničková, Jana ; Vítová, Eva (referee) ; Omelková, Jiřina (advisor)
The aim of this bachelor thesis is microbiology of raw milk and heat treatment milk, pasteurized and UHT treatment. There are described the most important and the most common microorganisms that contaminate milk, spoilage and pathogenic in the theoretical part. Practical part was provided in laboratory of diary factory. There were determined counts of microorganisms in raw, pasteurized and UHT milk by microbiological analysis.
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