|
|
Degradation possibilities of synthetic macromolecular materials centred on biodegradations
Zichová, Miroslava ; Ondruška, Vladimír (referee) ; Babák, Libor (advisor)
This work deals with the degradation possibilities of synthetic macromolecular materials. Mechanical, chemical and chemo-physical degradation is described, but the work is focused on biodegradation. Polymer biodegradation is its decomposition by microorganisms. The aim of the work is to show the advantages of biodegradation and to arrange the knowledge acquired about the biodegradation of particular macromolecular materials. There is resumed the information about the degradation of polyurethanes as an exception among synthetic polymers, which are mostly resistant to biodegradation. Attention is also paid to biodegradable polymers.
|
|
|
The optimization and validation of the GC-MS method for assessment of volatile aroma compounds in cheese
Koubek, Miroslav ; Babák, Libor (referee) ; Vítová, Eva (advisor)
This work deals with the introducing of the method for the determination of volatile aroma active compounds in different types of natural and processed cheeses. The theoretical part describes the basic groups of aroma compounds. Than the methods used for their determination with focusing on solid phase microextraction and gas chromatography coupled with mass spectrometry are described. The experimental part deals with the optimization of the selected method parameters. For extracting volatile substances from the sample matrix the fiber DVB/CAR/PDMS 50/30 m was selected, these compounds were then determined by gas chromatography coupled with mass spectrometry. In the frame of validating proces the repeatability of the method was verified, RSDs of retention times
|
|
|
Study of fruit ripening and storage
Langová, Jiřina ; Zemanová, Jana (referee) ; Babák, Libor (advisor)
There are many changes in fruit quality during its ripening and storage. The following four apple varieties were studied: Champion, Glostr, Golden Delicious and Idaret. Amount of reducing sugars, total amount of sugars, quantities of acids, refractive solids and loss of starch were monitored. The changes of parameters, the differences between the varieties and differences in storage were compared. Parameters were monitored from mid-August 2008, when the apples ripened. After the harvest, apples were stored in a cool box at 2 - 3 ° C and at room temperature 20 - 23 ° C. Apples stored in the cool box were analyzed till the end of March 2009, and apples stored at room temperature until the beginning of January 2009. Total quantity of sugars in all varieties increases before harvest, while it decreases after picking the apples. The quantity of reducing sugars in apples rises gradually and after their picking it falls significantly in apples stored at 20 - 23 ° C. In apples stored in the cool box it continues rising until the end of November, and then it also decreases. Losses of starch are considerable and they are accelerated after the harvest. The quantity of acids also decreases throughout and amounts of refractive solids increases. For all varieties there are significant changes in storage at 20 - 23 ° C. Temperature, therefore, significantly affects processing of sugars and acids in fruit respiration.
|
|
|
The content of chosen mycotoxins in feeds
Zelníčková, Lenka ; Babák, Libor (referee) ; Kellnerová, Dita (advisor)
This diploma thesis is focused on current problematics of monitoring of selected mycotoxins, DON and ZEA, in feeds in Czech Republic. The objective of my thesis was to elaborate a literature search from available books, electronic and periodical sources and service materials. Literature search is aimed at overall overview of mycotoxins, describes their characteristics, biological effects, methods of detection as well as summarizes recent legislation requirements concerning occurrence of these substances in feeds for animals. The aim of experimental part was a determination of selected mycotoxins in feed (DON and ZEA) by ELISA method and their evaluation according to the maximum limits. The diploma thesis was prepared in diagnostic laboratory SEVARON, s. r. o. in Brno.
|
|
|
Biosorption ability of thermophilic cultures
Zichová, Miroslava ; Vránová, Dana (referee) ; Babák, Libor (advisor)
The aim of this master's thesis is to study the biosorption of heavy metals copper, lead and zinc on thermophilic bacteria of the genus Geobacillus – G. thermodenitrificans CCM 2566 and G. thermocatenulatus CCM 2809. Biosorption was carried out in a batch stirred system for each metal separately. The influence of pH, biomass concentration and initial metal concentration on sorption capacity of bacteria was investigated. For both bacteria the optimum biosorption pH values for copper, lead and zinc were 5; 4 and 5, respectively. Sorption capacity of both bacteria was higher at lower concentrations of biomass and increased with increasing initial metal concentration. The confrontation of sorption capacities showed that the bacterium G. thermocatenulatus has greater sorption potential than G. thermodenitrificans.
|
|
|
Assessment of aroma active compounds in currant
Lišková, Michaela ; Babák, Libor (referee) ; Vítová, Eva (advisor)
This master thesis deals with the assessment of aroma active compounds in fruits of currant (Ribes spp.). The theoretical part was focused on basic characteristics and chemical composition of currants, as well as the basic principles of techniques used: solid phase micro extraction (SPME), gas chromatography (GC) and sensory analysis. The main aim of the experimental part was to determine aroma active compounds in currants using SPME-GC-FID method. The profile and scale tests were used for assessment of sensory quality and tastiness of fruits. In total 18 varieties, among them 6 white, 6 red and 6 black currants, were evaluated. Fifty aroma active compounds were identified including 21 alcohols, 10 aldehydes, 2 acids, 8 ketones and 9 esters. The results were statistically evaluated using principal component analysis (PCA) to investigate the influence of single compounds on sensory quality of fruits.
|
|
|
Thermophilic microorganisms
Sůkalová, Kateřina ; Vránová, Dana (referee) ; Babák, Libor (advisor)
This bachelor’s thesis is focused on distribution thermophilic species from among microorganisms, characteristic important genera, in which these microorganisms we can find and detailed description choice species. There is described origin of thermal environment and locations of habitation thermophilic microorganisms with intention on geothermal areas, where is found the biggest number of these species. In consequence of thermal stability of enzymes these microorganisms are used in food industry, in waste treatment, in medicine and for their production of thermostabile enzymes.
|
|
|
Production of polyhydroxyalkanoates from waste substrates and their isolation
Grossová, Marie ; Babák, Libor (referee) ; Márová, Ivana (advisor)
The aim of this work is to study the possibility of microbial production of polyhydroxyalkanoates (PHA). PHA can be used as biodegradable materials. Bacterial strain Cupriavidus necator was used for laboratory production of PHA. This bacterium was cultivated in medium with various precursors to produce copolymers of 3HB with 3HV or 4HB. Another part of the work was aimed at cultivation of C. necator on different waste substrates, especially oils, with the aim to achieve the highest production of polymer. Another large part of the thesis is dedicated to isolation strategies of PHA using enzymes. Commercially used proteases – alcalase and pancreatin – can be used with advantages for digestion of bacterial cells. A number of optimization experiments showed that application of proteases leads to enhancement of PHA purity to about 13%. Purity increase up to 90 % was achieved by adding a surfactant, which promotes the solubility of non-PHA forming polymer. This surfactant increases the purity of 20 % when compared to control. The last part of presented work deals with the use of enzyme solution isolated from Bacillus subtilis medium. Its application to C. necator culture led to the yield of polymer at a purity exceeding 95 %. These results could represent the basis for new isolation strategies, which can lead to more efficient yield of PHA.
|
|
|
Iodine in food
Laba, Marija ; Babák, Libor (referee) ; Vránová, Dana (advisor)
This research addresses the importance of iodine as a micronutrient for the human body. Although it seems that the required daily intake is small and it is calculated in micrograms, it is equally important for the organism. The issue deals and summarizes the occurrence of this element in food. Insufficient or excess intake causes serious illness. Based on this research, it is possible to imagine a supply of iodine in the Czech Republic and in the world. The collected information shows that iodine intake is different and it is depending on food, health status or age. The locality in which we live plays a big roli. Currently the salt iodization and wrong eating cause the growing problem of excessive intake of iodine in the body. Since the problem is solved only in theory, we can find a description of the most ideal method for determining the amount of iodine in food.
|
|
|
Study of lipase production using selected microorganisms
Rošková, Hana ; Babák, Libor (referee) ; Omelková, Jiřina (advisor)
Diploma thesis was aimed at studying of lipolytic activity of seven microorganisms, at which this activity was previously assumed or already confirmed. Theoretical part deals with the general characteristics of lipoyltic enzymes, specifics of microbial lipases and their industrial application, with an emphasis on food industry. Experimental part deals with the study of seven microorganisms and their lipolytic activity at the presence of a carbohydrate (glucose) or a lipid (canola oil) or both, as a source of carbon. For further testing were singled out Rhodotorula minuta nad Yarrowia lipolytica. This yeasts were subsequently tested for lipolytic aktivity at the presence of different vegetable oils (olive, sunflower, canola oil and waste cooking oil), nitrogen sources of organic and inorganic origin (urea, yeast extract, amonnium chloride, amonnium sulfate) and also a addition of detergent, which is commonly used in food industry or other food facilities.
|
guest ::
