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Vliv receptury a délky zrání na obsah biogenních aminů ve zrajících sýrech
Trusinová, Adéla
The diploma thesis is focused on the content of biogenic amines (cadaverine, histamine, 2-phenylethylamine, tyramine and tryptamine) depending on the ripening time in 3 varieties of maturing cheeses (control sample, sample with laccase in the cheese dough, sample with laccase on the surface of the cheese). Furthermore, the work focuses on the effect of adding laccase to the dough and on the surface of the cheeses. The theoretical part is focused on the importance and occurrence of biogenic amines in food, including possible toxic effects on the organism. The practical part monitored the effect of ripening time on the content of biogenic amines in 3 variants of the same type of cheese in the ripening process. Biogenic amines were determined after derivatization with dansyl chloride by HPLC. The most quantitatively represented biogenic amine was cadaverine, which reached the highest concentration values after 14 days of ripening in cheese with laccase on the surface. The value of the concentration was 336 μg/100 g. The amount of laccase on the surface showed an opposite trend (p ˂0.05) when evaluating the storage time on the content of the concentration of biogenic amines, an opposite trend against cheeses with laccase in the dough. The concentration of the sum of biogenic amines in all cheese samples with laccase in the dough first decreased, then increased according to the equation y = 556.03–165.51x + 22.593x2 (R² = 0.4904; p = 0.14). The concentration of the sum of biogenic amines in cheeses with laccase on the surface, depending on the ripening time, first increased and then decreased according to the equation y = 150.42 + 631.63x - 97.921x2 (R² = 0.1999; p = 0.57). Most of the values measured in this work do not correspond to the normal content of individual biogenic amines in the literature, this fact may be caused by an inappropriate selection of the type of cheese for the determination of biogenic amines, an incorrect technological procedure during production or the fact that the filtration of the supernatants was very difficult and lengthy and with large losses. The influence of laccases on the formation of biogenic amines could not be unequivocally demonstrated due to the great variability of the data and few reference values with which the measured values can be compared. Laccases in food are a relatively new issue that is not sufficiently supported by literature sources and requires further investigation.
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Study of culturable anaerobic bacterial communities living in symbiosis with bark beetles; its isolation, taxonomy and biotechnical potential.
Fabryová, Anna ; Garcia-Fraile, Paula (advisor) ; Mrázek, Jakub (referee)
Microbial enzymes implicated in plant cell hydrolysis may have several potential aplications such as biomass degradation biocatalysts or with biofuel production. Bark beetles establish symbiosis with several microbial strains which play different roles benifitting the beetle, as the production of hydrolytic enzymes to degrade the ingested wood, the protection against mirobial antagonist or the detoxification of the environment. Fungal symbionts have been traditionally the best studied, but several recent research with bacterial symbionts of several bark beetle species show that bacterial also display important functions for the host. In this study, the bacterial communities of the bark beetle species Cryphalus piceae and Pithophtorus pithophtorus, collected in the Czech Republic from pine and fir trees, respectively, were isolated and 55 out of 89 samples were identified by 16S rRNA gene amplification and sequencing. Members of the genera Erwinia, Pantoea, Curtobacterium, Yersinia, Pseudomonas and Staphylococcus were detected. The isolates were object of study for their possible biotechnological potential in (ligno)cellulose materials degradation by screening several enzymes implicated in plant cell hydrolysis, as cellulases, xylanases, amylases, laccases, as well as their capability for colorant...
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