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Metabolic activity of mezophilic milk souring in production of cheeses with white fungus
Štěpničková, Jana ; Vítová, Eva (referee) ; Babák, Libor (advisor)
The thesis was processed in cooperation with Pribina s.r.o. The aim of the thesis was the monitoring of the starters of cheeses with the white fungus on the surface. The thesis was engaged in the monitoring process of a souring curve of used starters. This monitoring was based on temperature, titrating acidity and pH measured in the time interval. The souring curve was evaluated as the indirect measurement change of acidity of the starter in the time period. Further, the activity of detached starters was measured. The measurement was based on the change of pH measured in the time period. The influence of the culture medium was monitored by changes in behaviour of the bacterial cultures. The monitored starters were compounded of mezophilic and termophilic bacterial strains.
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Rowanberry - nutritional characteristic and utilization in grocery
Andrlová, Kateřina ; Vítová, Eva (referee) ; Vespalcová, Milena (advisor)
Bachelor elaborate is focused on one the less used species of small fruits - rowanberries. It gives an overview of the particular biologically active substances in this fruit and the use of the fruits in the human diet. Introduction is focused on the botanical description of rowan - Sorbus. There are presented the best known species of genus rowan. The greatest attention is paid to the type of Sorbus aucuparia which provide sweet variety and nutritional value of the fresh fruits. The second part is devoted to the description of biologically active substances contained in food rowanberries. The most valuable of them are vitamin C, flavonoid compounds (quercetin, campferol), phenolic compounds (chlorogenic acid) and pectins. Possibility of processing rowanberries in a variety of products are presented in next part. They are made of these compotes, jams, candied fruits, jellies and juice. Can be used for production of wine, cider and liqueur. In conclusion, there are described methods for determination the content of selected substances rowanberries (vitamin C, pectins). There are mentioned here primarily manual methods.
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Yeasts in wine making process
Horká, Daniela ; Vítová, Eva (referee) ; Vránová, Dana (advisor)
This bachelor thesis deals with an observation of yeasts cell influence on the wine production process and also on its final property. Yeast cell isolation and identification from Green Veltliner wine variety of grape juice were made. Basic microbiological operations and molecular – biological methods based on PCR – RFLP were used. Monitoring of chemical changes in fermented Hibernal variety of grape juice with using spectrophotometric method was carried out. The total antioxidant activity of fermented grape juice and pH were the parameters which were measured. Autochtonous yeast which was isolated fromthe berries surface in our laboratory last year was used during production of the Hibernal varienty of grape juice. Specialized literature for the chosen topic were analysed within this thesis. Moreover, history of wine production, grapewine charakteristics, morphological structure and chemical composition of grapes were desribed. Partial stages of the wine production technology, final wine modification and principles of used methods were investigated at the end of the thesis.
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Preparation and study of selected essential oils
Chmelová, Nikola ; Vítová, Eva (referee) ; Zemanová, Jana (advisor)
The theoretical part of this bachelor thesis is focused on the characteristics, effects and use of essential oils. There are also described methods for isolating essential oils from plant materials, identification options methods suitable for assessing their quality. Within the experimental part essential oils of the Plectranthus amboinicus and Mentha piperita were prepared. Ethanol extraction and automatic hexane extraction using Gerhardt Soxtherm instrument were used for the isolation. The substances occurring in the essential oils made of Plectranthus amboinicus and Mentha piperita were analysed using a gas chromatograph with a mass detector. The aim of this thesis was to find out what potentially allergenic substances are contained in essential oils.
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Comparison of content anthocyanin pigments in selected cultivars of black elderberry and grape
Becková, Eliška ; Vítová, Eva (referee) ; Vespalcová, Milena (advisor)
The purpose of this thesis is to compare the contents anthocyans in different varieties of European elderberry (Sambucus nigra L.). It was also studied the relationship between the content anthocyans in selected samples of blue grape varieties (Vitis vinifera L.) and position of the track, where the grapes were grown. The theoretical part describes elderberries and grapes in terms of botanical, chemical, and in terms of their using in the food industry. The dominant part of this chapter is to describe anthocyans and possibilities for their determination in the elderberry and grapes. Emphasis has been placed on the pH-differential method and determination by high performance liquid chromatography. The experiments are divided into two parts. The aim of the first experimental part is comparison of the total anthocyanins content in fifteen varieties of elderberry. The performed analysis shows that in terms of anthocyanins content for cultivation of elderberry in the Czech Republic the most suitable varieties are Mammut, Samyl, Reis aus Vossloch and Haschberg. In the second part of the experiments were determined total anthocyanins content in nine varieties of blue grape grown in the Mikulov region. For determination were used HPLC and pH-differential methods, as well as in the first part. The highest content of pigments was found in varieties Alibernet and Neronet. The present study focused on the suitability of the location pointed to vineyard south to southeast orientation plantings. At the end of the experimental part is a comparison of both methods of determination. Method using high performance liquid chromatography to provide very accurate results compared to less demanding pH-differential method of determination. This is recommended only for tentative determination of anthocyanins content in real samples.
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Application of spectral and non-spectral analytical methods for monitoring the quality of ketchups
Havlíčková, Barbora ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
The aim of the master´s thesis was to verify the applicability of elemental analysis and molecular spectrometry for examining the authenticity of ketchup. For verify of share refractometric dry matter introduced into ketchup from tomatoes was used analysis of potassium and lycopene content. Ketchups with different tomato contents were prepared and subsequently models were created, which were used to verify the proportion of refractometric dry matter introduced into tomato ketchup in ketchups from the store. The results of the work showed that the amount of lycopene is a problematic marker for verifying the authenticity of ketchup, because during the production of ketchup, lycopene is degraded.In contrast, the amount of potassium in ketchup has been shown to be a good marker for monitoring the authenticity of ketchup. The model based on the potassium content of ketchup worked reliably, the deviations obtained from the quantity of tomatoes used for the production of ketchup indicated on the packaging were less than 10%. Higher deviations were achieved in ketchups with a minimum permitted tomato content of up to 20%. The concentration of potassium in ketchup with a lower content of used tomatoes can be significantly affected by the addition of other ingredients to the ketchup (onion, garlic, carrot, apple, etc.). In addition to the ketchup production technology used, the ripeness of tomatoes also has a significant effect on the model for verifying the authenticity of ketchup.
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Sensory quality of chosen types of beer
Lišková, Michaela ; Divišová, Radka (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the sensory guality of chosen types of beer. The teoretical part was focused on the production of malt and beer and raw materials needed and also an introduction to sensory analysis was described. The experimental part was focused on evaluation itself. Nineteen untrained assesors were invited for sensory evaluation, who evaluated five selected beer kinds using the preprepared form. Unstructured graphic scale with a verbal description of anchor points was used to evaluate the appearance and color, taste and odour, fullness, bite, foaming, bitterness and any off-taste or off-odour of each sample. Five-point category ordinal scale was used for assessment of the overal acceptability of the samples. Results of the analysis were then evaluated graphically and statistically.
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Characterization of lipids in fresh cheeses
Vaňková, Veronika ; Křikala, Jakub (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the determination of fatty acids in samples of fresh cheeses with or without the addition of plant extracts (rhyme, echinacea), produced in laboratory conditions at FCH BUT. The theoretical part of the thesis focuses on the general characterization of lipids and fatty acids. The next part discusses the characterization, division, and methods of cheese production, focusing mainly on fresh cheeses. The end of the work is devoted to gas chromatography as a method for the determination of fatty acids in cheese samples. The experimental part aimed to determine the content of fatty acids in the samples of fresh cheese. For the extraction of lipids from cheese samples, the choice of the method was according to ČSN EN ISO 1735. Acid esterification with boron trifluoride as a catalyst was used for the preparation of fatty acid methyl esters. The determination of fatty acid methyl esters was performed by gas chromatography with a flame ionization detector (FID). A total of 14 fatty acids were identified in all samples in a bound and free form. Myristric, palmitic, stearic and oleic acids predominated in all samples, which is in agreement with the knowledge of the composition of milk fat. The obtained results show, that even due to slight differences in the content of individual fatty acids, the addition of extracts does not affect the composition of fatty acids in fresh cheeses.
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Monitoring the nutritional profile of edible fats and oils after culinary treatments
Chadimová, Markéta ; Vítová, Eva (referee) ; Němcová, Andrea (advisor)
This diploma thesis studies changes in the nutritional composition (especially fat changes) of selected fats and oils after various culinary treatments and during their storage under unsuitable conditions. Fats and oils are classified as so-called triacylglycerols, ie they are composed of glycerol and three fatty acids. It is the fatty acids bound to glycerol that determine the properties of fat and its stability. Eight types of fats and oils (sunflower oil, rapeseed oil, olive oil, coconut oil, linseed oil, butter, ghee and lard) were used for the analysis. The flaxseed oil sample was stored for 3 months in unfavorable storage conditions, ie in the light and in the heat. Other fats and oils were used for frying, baking, stewing, grilling and frying meat and onions. The aim of the work was to compare changes of fatty acids, changes of fat numbers and compare the amount of vitamin E contained in individual oils before and after culinary treatments. The results of the analysis showed that fat samples did not show significant changes in fat numbers, fatty acids or vitamin E after culinary treatments or improper storage. From this I conclude that fats and oils have been exposed to high temperatures and unsuitable conditions for a short time. The largest difference in the composition of fatty acids was measured for sunflower oil, where a higher amount of trans fatty acids was measured after treatment and overall a lower proportion of PUFA was measured than before treatment. As sunflower oil has a high content of polyunsaturated MK and a low smoke point, this result was expected. The highest concentration of vitamin E was found in rapeseed oil.
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