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Analysis of sweet peppers of different geographical origin
Fiala, Petr ; Mikulíková, Renata (referee) ; Diviš, Pavel (advisor)
The diploma thesis is focused on the determination of basic nutritional properties of 26 samples of ground pepper from different countries and evaluates, whether the chemical composition of ground pepper is affected by the geographical origin. The amount of 19 nutritional properties were determined by advanced analytical methodes (ICP-OES, HPLC DAD, HPLC ELSD) together with other laboratory techniques. Final results were statistically processed by the methods of analysis of variance (ANOVA), cluster analysis, principal component analysis (PCA) and discriminant analysis (DA). Statistical evaluation confirmed, that the chemical composition is affected by the geographical origin. Analysis of variance (ANOVA) determined 14 parameters to statistically differ (p
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Bioflavouring of beer using new Czech hop varieties
Ondruch, Petr ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis focuses on bioflavouring of beer using new czech hop varieties. Dry hopping is a phenomem, that contributes to the attractiveness and diversity of beer and is nowadays gaining in popularity. The aim of this work was to determine the effect of dry hopping on sensory profile and analytical parametrs of dry-hopped beers using czech hop varieties. Sensory evaluation and chemical analysis of these beers were taken. The chemical analysis included determination of the basic beer characteristics, total phenolic a flavonoid content, antioxidant activity and the concentration of selected organic acids and chemical elements. It was found out that dry-hopped beers compared to the reference beer presented higher bitterness, antioxidant activity and contained higher amount of flavonoids. Also an increase in pottasium, manganese, copper, calcium and malic acid levels was reported. The pH of beer samples was not affected by dry hopping. Sensory evaluation showed that dry hopping had a positive influence on the overall enjoyment of the beer, which was mainly determined by the higher aroma and more intense bitterness. By summaring all the data, it is obvious that dry hopping of beer using new czech hop varieties has a positive effect on the quality of the final beer and these hop varities are suitable for further use in the beer industry.
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Chemical and sensory analysis of fruit juice from selected cultivars of European elder
Ješková, Kristýna ; Vespalcová, Milena (referee) ; Hrstka, Miroslav (advisor)
The aim of this thesis is the chemical and sensory analysis of the juice from fruits of cultivated varieties of elderberry (Sambucus nigra L.). In the theoretical part botanical description of elderberry including its distribution and places of existence are given. There are also mentioned medical effects and collection of various parts of the elderberry as well as breeding certain species and methods evaluating sensory features of the juice samples prepared from the cultivated varieties of elderberry. In the experimental part some chemical parameters (yield, soluble dry matter content, relative density, pH, titratable acidity, formol number, reducing saccharides) in the juice of berries of eighteen cultivated varieties of elderberry were determined. In fifteen cultivated varieties was made sensory evaluation using profile test and scale. The aim of the evaluators in the evaluation using scale was to evaluate the taste, smell, sensory quality and preferences according to seven point cathegorical hedonic scale. In the profile test, five point scale was used to evaluate the intensity of chosen flavours: acidic, sweet, bitter and others. Overall impression of the sensory evaluation was rather not positive. In majority of the samples the taste and smell were evaluated as good or satisfactory and their general acceptability, too. The juice from the wild elderberry was estimated as worse than in other samples, its taste, smell and overall acceptability were unsatisfactory. In majority of the cultivated varieties were the taste and smell estimated as unsatisfactory as well as their general acceptability.
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Refractory Products for Aluminum Metallurgy Industry
Kupcová, Zuzana ; Lang, Karel (referee) ; Nevřivová, Lenka (advisor)
The master´s thesis focuses on high-alumina refractory materials used mainly in aluminia metallurgy. Teoretical part of this thesis is aimed at distribution of refractory materials, possibilities of its production and raw material basis. Characteristic properties are described as well as application possibilities in aluminium technology. In final part of this thesis experimental data are evaluated to obtain physical, mechanical, chemical properties of high-alumina refractory materials. Those are used for economical optimalization of raw materials.
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Hodnocení fyzikálně-chemických parametrů zrajících sýrů
Strojilová, Hana
The diploma thesis on the topic "Evaluation of Physicochemical Parameters of Ri-pened Cheeses" deals with the topic of the history of cheeses and their composition in its theoretical part. The thesis also mentions the importance of dairy products in nutri-tion. Other chapters are devoted to the technological production of cheeses with low-heated and high-heated cheese curd and their important representatives. In the last chapters of the theoretical part there is a general description of the used methods for the determination of fatty acids in the formulas. The experimental part of the thesis is focused on basic analytical methods that allow control of individual components of cheese with its packaging. At the same time, a comparison of sampling of Gouda chee-se and Edam cheese was made. Additionally, an experiment was carried out in the ex-perimental part, during which individual fatty acids were extracted. The extraction of fatty acids was carried out according to the method of Hara and Radin. The samples were derivatized and analysed by using a gas chromatograph. Individual percentage values of acids were compared in all samples together. Furthermore, the content of individual fatty acids was evaluated with samples compared by type of cheese. For the experimental part, samples of cheeses with low-heated cheese curd were used there.
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Bioflavouring of low alcoholic beer by dry hopping
Dušánek, Václav ; Mikulíková, Renata (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the influence of cold hopping of low-alcohol beers on analytical properties and sensory profile of beer. The effect of cold hopping was observed using the varieties Kazbek, Jazz, Mimosa and Uran. In the experimental part, the production process of low-alcohol beer using immobilized yeast is described. After the main fermentation, the low-alcohol beer was kegged into five cuvettes and after 20 days cold-hopped at a dose of 3 g/l with individual varieties. The effect of cold hopping with individual varieties on the organoleptic properties of the beer was observed. Bitterness was determined, with cold-hopped beers showing an increase between 17-24 % in bitterness. Furthermore, the ethanol content was determined by high-performance liquid chromatography at 2,14 % vol. A significant increase in all volatiles, in particular -myrcene and linalool, was found in the cold-hopped beers by gas chromatography with mass spectrometry. The sensory analysis showed that the cold hopping had a positive effect on the overall impression and masked the taste defects of the reference low-alcohol beer. The best hop evaluated for the use of the cold hopping method was the Kazbek variety. The Jazz and Mimosa varieties were also perceived relatively positively by the evaluators. On the other hand, the Uran variety achieved a worse overall impression than the reference beer.
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Hodnocení jakosti bílých jogurtů v závislosti na obsahu tuku vstupní suroviny
Šťastná, Magdaléna
The thesis aimed to evaluate the quality of plain yoghurt depending on the fat content of the input raw material. The literature part is focused on the legislative requirements and classification of fermented dairy products and plain yoghurt, the raw materials from which plain yoghurt is produced and the basic technological operations of the production process. In addition, mention is made of vegetable fats and their use in the manufacture of alternative dairy products. The practical part deals with the production of yoghurts with different fat contents and different raw materials (animal and vegetable fat). Experimentally produced samples were subjected to Physico-chemical and microbiological analysis. A sensory questionnaire was developed and the yoghurts were sensorially evaluated. Finally, it was assessed whether the use of vegetable fats as a fat additive in the manufacture yoghurts is possible. The result showed that the use of vegetable fats to produce yoghurts of lower fat content would be possible without negative effects on quality, provided that this was allowed by legislation. According to Czech legislation, only a product containing a dairy raw materiál may be called yoghurt. Therefore, this product could not be called yoghurt, but an alternative dairy product.
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Hodnocení jakostních parametrů kozích jogurtů v závislosti na vstupní surovině
Němcová, Vendula
The aim of the work was to evaluate the physico-chemical and microbiological parameters of organic goat yoghurts and milk, which was used for their production. The results were evaluated depending on the season and storage time of yoghurts. Sampling took place during spring, summer, autumn and winter. The sampling schedule during storage was chosen according to the shelf life given by the producer with the possibility of extending the shelf life of the product. The evaluated parameters included dry matter, fat, protein and lactose content, titratable and active acidity and microbiological analysis (total number of microorganisms, lactic acid bacteria, psychrotrophic microorganisms, coliform bacteria, enterococci and micromycetes). Goat's milk and, depending on it, yoghurts were subject to seasonal changes in composition with a higher dry matter content in winter and lower in summer. These differences were also reflected in the different titratable acidity and the total number of microorganisms. No coliform bacteria were present in the yoghurts. Enterococci, psychrotrophs and micromycetes (mostly yeasts) have been reported. Between the 3rd and 13th day of storage the number of psychrotrophs and micromycetes increased significantly. For yeasts and molds, another significant increase followed between the 18th and 24th day of storage. Only slight post-acidification was observed during yoghurt’s storage.
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Evaluation of the yield and quality of table potato tubers
KAŇKA, Jakub
The aim of the diploma thesis was to evaluate the differences in yield, content of nutritionally important substances and table value of tubers in the selected set of ware potatoes. For this purpose, a small plot experiment was established in Jindřichův Hradec with 3 varieties of ware potatoes: Rosara, Sunshine and Princess. The cultivation took place under the conditions of conventional technology. During the vegetation, the health of the growth, the onset of growth phases and the yield formation were monitored. Samples were taken from the harvested plots for examination and chemical analysis and then the yield was determined. The number of tubers per bunch and stem, the average weight of tubers, dry matter content, starch content, total polyphenol content and antioxidant activity were evaluated for individual varieties. Furthermore, the table value of tubers was evaluated by evaluators through a cooking test.
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