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Characterisation of chosen types of dairy products
Musilová, Lenka ; Buňka, František (referee) ; Vítová, Eva (advisor)
The aim of this thesis was to design technology of production soft cheese with white mold on the surface in a pilot plant conditions using unpasteurized milk that comes from grazing cows. This way I wanted to be closer to the traditional cheese manufacturing technology, over which today dominates the industrial. Final cheeses were subjected to sensory analysis in order to determine their acceptability for ordinary consumers. Sensory evaluation was carried out by two committees: students and seniors. Between the two committiees were noticeable differences, however, both commissions at the conclusion assessed the cheese as „good”. This evaluation was mainly based on lower ratings of taste (flavor) of the samples, which were quite strong and unusual for Czech consumers.
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Editting system for article reviews
Buňka, Roman ; Karásek, Jan (referee) ; Burget, Radim (advisor)
The objective of the thesis is an analysis, design and implementation of a web application which could be used by authors of articles, reviewers and the system administrator for automation of reviewing scientific articles. The reviewing analysis shows requirements required for the application from the viewpoint of users´ roles. The editorial system design deals with the application architecture and a plan of classes. The application is shown together with a description of its implementation.
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Assessment of chosen aromatic compounds in foods
Ascherová, Adriana ; Buňka, František (referee) ; Vítová, Eva (advisor)
This diploma thesis is focused on aromatic substances occurring in food. The theoretical part describes their characteristics, the use of fragrances of plant origin for flavoring of food and points to their possible negative effects on the human organism. Twenty six potentially allergenic fragrances are thus identified in European legislation and an overview of their physical properties, occurrence and use is also processed in this work.The aim of the experimental part was to develop and validate a method for assessment of fragrances using headspace solid phase microextraction combined with gas chromatography (HS-SPME-GC-FID). The following parameters have been validated : repeatability, linearity, limits of detection (LOD) and limits of quantification (LOQ). The HS-SPME-GC-FID method was finally applied to selected samples of foods commonly available on the market.
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Graphics and Presentation in the TeX and LaTeX Systems
Buňka, Roman ; Sysel, Petr (referee) ; Rajmic, Pavel (advisor)
This bachelor’s thesis deals with the insertion of external graphic files into LaTeX documents and the creation of graphics using internal tools of TeX. It describes the basic properties of the PSTricks additional package and its expansion enabling the creation of 2D and 3D graphs, special mathematical functions and electrical circuits. The work deals also with the method of creating PDF presentations using the Beamer class. This work suggests a structure of a source SVG file displaying electric circuits or flow charts. It also involves the creation of an XSLT conversion template providing for the conversion of these charts from the SVG format to the PSTricks format making it possible to use these graphic files in the LaTeX system.
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Characterisation of processed cheese analogues
Studýnková, Hana ; Buňka, František (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis was to identify and quantify the content of taste and aroma active compounds and to evaluate flavour of cheese analogue samples with various vegetable fats (coconut, palm, butter and mixed oils and butter) and differently matured Edam cheese using selected sensory methods. The samples were produced at Tomas Bata University in Zlín. Aroma compounds were extracted using SPME and assessed using gas chromatography. In total 43 compounds were identified, 14 alcohols, 9 aldehydes, 7 ketones, 8 acids, 5 esters and 1 terpene. Simultaneously the analogues were sensorially evaluated using scale, profile and ranking tests. The influence of storage time, type of fat and Edam cheese used on content of aroma compounds and sensory quality of analogues were evaluated. The cheese analogues with butter were sensorially evaluated as the best, with mixed oil as the worst. From the point of view of aroma compounds content, the significant differences between samples were evident. Using more matured Edam cheese, the content of aroma compounds declined, however, these samples were sensorially evaluated as better. The content of aroma compounds decreased also with storage time, which is more obvious in less matured Edam cheese. So all above mentioned factors influence the content of aroma compounds and thus the flavour of cheese analogues.
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Assessment of chosen aromatic compounds in foods
Škopová, Jitka ; Buňka, František (referee) ; Vítová, Eva (advisor)
The thesis deals with the issue of potentially allergenic aroma compounds in food. Aroma compounds suitable for food flavouring are mainly of plant origin. These aroma compounds and their mixtures have a lot of positive and negative effects on human organism. Although the aroma compounds are not among main groups of allergens, several studies indicate a potential risk of allergenic effects of some aroma compounds. The theoretic part of this thesis focuses on aroma compounds of plant origin and gives an overview of 26 the most important fragrance allergens according to the European cosmetic legislation. The aim of the experimental part was to verify the selectivity and appropriateness of the currently used methodology of headspace solid-phase microextraction and gas chromatography-flame ionization detection (HS-SPME-GC-FID) for determination of selected allergenic aromatic active compounds. Secondly, it is to use a proven method for a wide spectrum of real food products.
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Study of Formation and Elimination of Acrylamide in Food Matrix during Heat Treatment.
Marková, Lucie ; Jarošová, Alžběta (referee) ; Buňka, František (referee) ; Šimko, Peter (advisor)
Acrylamide (AA) is a probable human carcinogen and undesirable contaminant which is produced by the reaction of reducing sugars with asparagine in plant foods during their thermal treatment above 120 °C. AA is most often determined by GC-MS and LC-MS/MS in isolates from the matrix in a wide range of foods. According to our observations, AA intake from food is higher among young people (from 1.8 to 3.8 µg/kg bw/day), which is consistent with the estimations of JECFA FAO/WHO from the year 2006. Considering the health risk, it is recommended to reduce AA formation in food during its processing, in particular exploiting the available experience. The aim of this thesis was to extend the knowledge of the possibility of AA elimination in selected types of thermally processed foods. The study was focused on cereal foods that contribute significantly to AA exposure, especially bread and sweet biscuits. The whole AA content in the bread is in the crust, which represents 5-15% of the bread. Crust of home-made bread contains approximately 30-75 µg/kg, however the marketed bread contains 2 to 10 times more of AA. This is due to the composition of bread mix, preparation conditions and baking. For maintaining the quality of home-made bread during the dry mixture shelf-life, optimization of bread mixtures was designed by increasing of yeast content, which proved positive effect on the reduction of AA content at sufficiently high activity of the yeast. Monitoring of AA content in assortment of sweet bakery products showed higher levels of AA in diabetic biscuits containing fructose instead of sucrose. Three of them even exceeded the reference value (500 µg/kg) more than 1.5 times for commodity "cookies". Elimination of AA by applications of the enzyme asparaginase has been designed for minimal interference in technology of their production. The concentration of the enzyme and the appropriate method of its use in industrial environment have been tested previously in model systems. In optimized conditions of the enzyme application, AA content in diabetic biscuits was reduced by more than 40% without affecting the organoleptic properties of the final product. Effect of the antioxidants on AA formation was also part of the study. AA content in gingerbread was reduced efficiently by the use of fennel, anise, cloves, vanilla and white pepper (by about 9-21%). Conversely, coriander and cinnamon significantly increased its content (by 18-54%). Since correlations between the DPPH• radical quenching activity of the spice extracts and AA content was not observed, the final content of AA was probably influenced by the chemical composition of spices and reactivity of the individual components in the matrix. Investigated methods appear to be suitable ways of elimination AA in some foods; however their specific use must be optimized with regard to the composition of the food, processing and the technology used. Estimated impact of application of the above-mentioned methods to the overall elimination of AA exposure showed that its intake in high school students from the Czech and Slovak Republic can be reduced on average by 10%. This decrease is a success to reduce the possible risk of cancer disease by eating foods with a high AA content. It is also important piece of information for food producers for further development of relevant methods for AA elimination which would help to reduce the AA intake from foods even more.
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UTILIZATION OF FOOD PROCESSING WASTE FOR LACTIC ACID AND ETHANOL PRODUCTION
Hudečková, Helena ; Kráčmar, Stanislav (referee) ; Buňka, František (referee) ; Márová, Ivana (advisor)
The doctoral thesis is focused on the microbial production of lactic acid and ethanol using food processing waste as substrate. Coffee processing waste (spent coffee grounds), wine production waste (grape pomace) and orange processing waste (orange peel) were chosen as substrates for experiments. The theoretical part is dedicated to summarizing current knowledge about waste from food production and possibilities of its processing. It also deals with selected metabolites (lactic acid, ethanol) to which these wastes can be used. Part of the experiments was focused on the characterization and optimization of hydrolysis to maximize the amount of fermentable saccharides. Different combinations of chemical, physical and enzymatic hydrolysis of selected substrates have been tested. Subsequently, a suitable strain for lactic acid and ethanol production was searched for. In the case of lactic acid production, 7 bacterial strains were selected (Lactobacillus casei CCM 4798, Bacillus coagulans CCM 2013, Bacillus coagulans CCM 2658, Lactobacillus rhamnosus CCM 1825T, Lactobacillus delbruckii subsp. bulgaricus CCM 7190, Lactobacillus plantarum CCM 7039T, Streptococcus thermophilus CCM 4757). These strains were first cultivated on the synthetic media containing different kind of saccharides. Afterward, the cultivation on the waste biomass hydrolysates were tested. In the case of ethanol production, 2 yeast strains kmeny (S. cerevisiae CNCTC 6646 a S. cerevisiae CNCTC 6651) were cultivated on hydrolysates of individual waste substrates. Subsequently, the experiments focused on the production of lactic acid and ethanol on hydrolysates of waste biomass in bioreactor were done. The last part of this doctoral thesis deals with the microaerobic pretreatment of lignocellulosic biomass to increase the production of organic acids during the acetogenic phase of anaerobic digestion.
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Fragrance Allergens in Foods and Everyday Use Products
Divišová, Radka ; Buňka, František (referee) ; Hojerova,, Jarmila (referee) ; Omelková, Jiřina (advisor)
Fragrances are added to food, cosmetics and other products primarily for enhancement of their sensory quality (taste and/or aroma). However, the usage of these compounds is associated with the wide range of various adverse biological effects. Some fragrances widely used in cosmetics are proved to cause e.g. skin sensitization, rashes, dermatitis, headache, cough etc. To protect the health of consumers, European union approved the cosmetic directive (ES/1223/2009) that requires the labeling of 26 allergen fragrances on the final product label, if concentration exceeds the given level (0,01 % for rinse-off and 0,001 % for leave-on product). However, some producers hide the presence of allergens in the final product under the general term „aroma“. For this reason it is very important to monitor the content of these substances in cosmetic products. Fragrances are found not only in cosmetics, but the various types of food are also aromatized by them. Unlike cosmetics, the food producers are not obliged to label the presence of fragrance allergens on the packaging. Therefore, the monitoring of these fragrances is highly desirable because of the potential health risks they pose. The aim of this study was to develop a method for simultaneous determination of regulated fragrance allergens in food and everyday use products. The method based on extraction of analytes by solid phase microextraction coupled to gas chromatography with FID detection (HS-SPME-GC-FID) was chosen on the basis of the literature review. The fiber CAR/PDMS provided the highest extraction efficiency among the SPME fibers tested. Univariate and multivariate data analysis were used to optimize the main parameters affecting microextraction process. The final method validation was performed in terms of linearity, repeatability, reproducibility, recovery, limits of detection and quantification. The optimized and validated method was applied to a wide range of products including cosmetics, aromatized food and fragranced toys. These products were also subjected to sensory evaluation especially in terms of taste and/or aroma (i.e. flavour), which may be associated with the content of the monitored fragrances. The profile test (EN ISO 13299) and seven-point category ordinal scale (ISO 4121) were used for sensory evaluation.
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Characterisation of processed cheese analogues
Chlebcová, Lenka ; Buňka, František (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the topic of cheese analogues, their characterization and qualitative and quantitative analysis of processed cheese analogues for determination the taste and aroma active compounds. The overall character of processed cheese analogues is theoretically compiled in the introductory part. Their utilization, causes of the production, market introduction, technological production process and microstructure, including their comparison with classical processed cheese are given here. Various kinds of fats were used for production of analyzed cheese analogues, therefore commonly used ingredients for their production, their physical-chemical and sensory properties have been described. Specifically butterfat, milk fat, coconut fat, palm fat and mixed oil. Samples used for the practical part of the diploma thesis were made at Tomas Bata University in Zlín. In the experimental part the profile of aroma compounds in individual cheese analogues samples was assessed by SPME-GC analysis. In total 34 compounds were identified. The results were evaluated and compared, with emphasis put on the influence of storage, different fats, different maturity of Edam cheese on the content of aroma active compounds and on overall sensory quality of the analogues.
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