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Characterisation and maturation process of Edam type cheese
Dostálková, Andrea ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the assessment of aroma compounds and free/bound fatty acids in model samples of Edam type cheeses. Various combinations of microbial cultures, basic mesophilic and four selected strains of thermophilic Lactobacillus casei and Lactobacillus plantarum, were used for cheese production. The main aim was to judge the influence of microbial cultures on content of measured parameters, the changes during ripening were also followed. The HS-SPME-GC-MS method was used for identification and semiquantification of aroma compounds. The lipids from cheese were extracted based on ISO 1735:2004, fatty acids were identified and quantified using GC-FID method after conversion to methyl esters by acid esterification with boron trifluoride in methanol. In total 50 volatile compounds were identified in samples, 11 alcohols, 5 aldehydes, 7 ketones, 6 acids, 10 esters, 3 lactones, 2 sulphur compounds and 6 „others“; all of them are considered as aroma active. About 30–40 compounds were identified in single samples, alcohols, acids and ketones were the predominant. The number as well as the content of compounds identified decreased slightly during ripening. In total 17 free/bound fatty acids were identified in samples, their content also decreased during ripening. Myristic, palmitic, stearic and oleic acids were the predominant. The significant differences (p
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The selection and optimization of the method for assessment of free fatty acids
Koval, Dominik ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This master´s thesis deals with optimization and validation of method for determination of free fatty acids. The theoretical part is focused on possibilities of extraction, extract separation, esterification, gas chromatography determination and brief description of the most important validation parameters. All with main emphasis on applying on free fatty acids. The experimental part describes the selection and procedure of optimizing individual steps of the method. Extraction of lipids was performed by solvent mixture (diethylether/petroleumether), based on the standard ČSN EN ISO 1735, for the extraction of free fatty acid solid phase extraction was tested. The acid catalyzed esterification based on ČSN EN ISO 5509 using methanolic solution BF3 was used for derivatization of free fatty acids and a gas chromatograph with a flame ionization detector was used for their determination. Subsequently, selected validation parameters of the method were verified: repeatability, reproducibility, linearity, limits of detection and quantitation. Sunflower oil and emmental type cheese, bought in common food market, were used as model samples for selection and optimatization of the method.
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RECONSTRUCTION AND REBUILDING OF CITY BREWERY IN VYŠKOV
Vršanová, Dominika ; Zemánek, Václav (referee) ; Boháč, Ivo (advisor)
The bachelor thesis will solve the design of the transformation of the existing premises of the original bishop's brewery with a three-hundred-year tradition into a multifunctional complex fulfilling the following tasks. Renewal of production in the form of a small city brewery, adding new functions for the presentation of the brewery and cultural and social events. Reconstruction and completion of architecturally valuable objects, adding new objects for new functions.
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Characterization of cheese analogues produced with addition of nut oil
Mitra, Michal ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This thesis deals with the production and characterization of cheese analogues, i.e. products where some of the dairy components are partially or completely replaced by a non-dairy component. Model samples – Eidam type cheese and analogue with the addition of pistachio oil, were produced by a conventional technological process at MENDELU in Brno. Free and bound fatty acids, volatile substances and sensory quality were selected and monitored as the main characterizing parameters of the sample quality. The aim was to characterize the differences between the samples caused by the addition of nut oil in the monitored parameters. The HS-SPME-GC-MS method was used for the identification and semi-quantification of volatiles. The extraction of fats from the samples was performed with a mixture of solvents (diethyl ether, petroleum ether), fatty acids were converted to methyl esters by acid esterification with methanolic solution of boron trifluoride as a catalyst and subsequently identified and quantified by GC-FID. Descriptive scales and comparisons with standard were used to sensory evaluate the appearance, color, texture, odor, taste, and overall acceptability of the samples. The structure was monitored by electron microscopy. The results show that the addition of pistachio oil affects the sensory properties, the maturation process (higher content of volatile substances), the nutritional value (increased content of unsaturated fatty acids) and the stability of the product.
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The repeatability of the method for assessment of free fatty acids
Buldra, Martin ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the assessment of free fatty acids in sunflower oil. Theoretical part focuses on the general characteristics of fatty acids and lipids. The experimental methods suitable for assessment of fatty acids are described, with the emphasis on gas chromatography, the basic method of their assessment. In experimental part two methods for free fatty acids assessment: with/without previous fractionation, were compared and then the repeatability and reproducibility of selected method – the direct esterification of free fatty acids using BF3 as a catalyst, were verified. The assessment of fatty acids methyl esters was done using gas chromatograph with flame-ionization detector.
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Characterization of nut oils
Coufalová, Dominika ; Sýkora, Michal (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the characterization of selected nut oils, almond and pistachio virgin oils. The teoretical part concentrates on the description of nut fruits, the characterization of aroma-active compounds, fatty acids and their content in the nut oils. After that, the fatty characteristics, which determines the oil quality, and instrumental methods selected for individual assignment are described. In the experimental part there were 42 volatile compounds identified in the nut oils by the headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry, 35 were found in almond oil and 24 were found in pistachio oil. Free and bound fatty acids were converted into methyl esters using acid-catalysed esterification with boron trifluoride-methanol solution as a catalyst and then they were determined by gas chromatography with flame ionization detection. There were 12 fatty acids identified in almond oil and 14 fatty acids in pistachio oil. Oleic acid and linoleic acid predominated in both samples. The quality and properties of nut oils were valued by determining the fatty characteristics (acid value, saponification value, ester value, iodine value by Hanus method and peroxid value). The increased value of peroxide value was found in both oils which correlates with the trait and storage time of samples.
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Teaching-space paradigm
Vašička, Pavel ; Müller, Rudolf (referee) ; Rozwalka, Szymon (advisor)
The aim of the bachelor's thesis is to create a new Faculty of Architecture in close proximity to the Faculty of Fine Arts on the BUT campus. The aim was to achieve a dignified environment for teaching future architects. In the complex there is a building designed for the Faculty of Architecture. However, it does not have sufficient capacity to cover teaching needs. Therefore, both the existing building and the extension and their interconnection were solved within the project. The main goal of the project was to create an environment that reflects today. The architect in particular should have a more general overview. The premises are as open and shared as possible, so that the students themselves enrich each other as much as possible. Emphasis is placed on the open layout of the interior, into which the exterior blends in selected places, the floors are enriched with atriums and elevated floors, which allow greater social contact.
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The use of solid phase extraction for fractionation of lipids in cheese matrix
Scholzová, Kristýna ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with Solid Phase Extraction, as a method for isolation of free fatty acids from cheese matrix to be subsequently determined using gas chromatography with FID detection. The theoretical part provides information about milk fat composition and related reactions being a source of flavour compounds, free fatty acids including. The main objective of the theoretical research is to summarize alternatives to determining fatty acids in cheese, focusing on current advancement and use of Solid Phase Extraction for this purpose. The practical part discovers proper technique and conditions for fractionation of lipids by Solid Phase Extraction, using aminopropyl bonded phase columns. Agilent SampliQ Amino columns were utilized to separate lipid mixture and different lipid classes were eluted using suitable organic solvents. Composition and purity of lipid extracts were verified combining thin layer chromatography and gas chromatography. Before being determined by gas chromatography, free fatty acids were converted into methylesters, based on ČSN EN ISO 12966-2. Besides discussing proper experimental conditions, the assesment also comes with solving optimal volumes of sample and eluting solvents to apply. The results of this thesis are considered to be useful base for subsequent experimental optimization and following integration of validated method into process of determining free fatty acids.
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Production and characterization of fresh cheese analogues with the addition of nut oils
Lovásová, Kristína ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
Diploma thesis deals with the production and characterization of fresh cheese analogues with added nut oils (walnut, hazelnut, and almond oil). The purpose of the thesis was to prepare cheese samples with an improved nutritional value and better sensory quality. The experimental part deals with the characterization of the prepared samples in terms of fatty acids, volatile substances, content of fat in dry matter, antioxidant activity and sensory quality. Fatty acids were determined using the gas chromatography with a flame-ionization detector after the conversion to methyl esters by the acid esterification with boron trifluoride. The determination of the volatile compounds was performed through the solid-phase microextraction with the gas chromatography separation and the mass spectrometry detection. After the extraction and drying the samples, the dry matter and fat content in the dry matter was determined. Antioxidant activity was determined by the Trolox equivalent antioxidant capacity method and the sensory quality was assessed by the evaluators. In the comparison of fat in the dry matter there was a difference between the standard sample and the analogues. The samples with the added oil were higher in fat content that the standard sample without oil. All samples can be classified into the category of half-fat cheese. A total of 17 fatty acids were identified. The total content of fatty acids did not differ significantly. With the addition of nut oils, the amount of saturated fatty acids decreased and the amount of mono- and polyunsaturated fatty acids increased. A total of 40 volatile (aroma) compounds were identified in all samples. 22 compounds were identified in the standard sample; 25 compounds in the sample with walnut oil; 26 with hazelnut oil and 27 with almond oil. Alcohols, acids, and ketones were present in the largest amounts. The measured antioxidant activity of the analogues was higher that the activity of the standard sample. The highest activity was measured in the sample with walnut oil. From the sensory perspective the sample with hazelnut oil was evaluated as the best. The sample with walnut oil was evaluated as the worst. Added oils influenced the taste and the odour of the analogues but they also had an impact on the texture and the hardness of the samples. The obtained results indicate that the addition of nut oils influences the properties of cheese. It increases the nutritional value (lower amount of saturated fatty acids and higher amount of unsaturated fatty acids, higher antioxidant activity) and, except for the sample with walnut oil, even the sensory quality and the acceptability were evaluated as better.
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