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Production and characterization of cheese analogues with the addition of vegetable oil
Babištová, Lucie ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This thesis deals with the production and characterization of cheese analogues, ie products in which some of the dairy components are mutually or completely replaced by a non-dairy component. Model samples of fresh cheese and analogues of fresh cheese (standard) with the addition of linseed and rapeseed oil were produced by a standard technological procedure in MENDELU Brno. The content of bound and free fatty acids, volatile (aroma) substances and sensory quality was monitored in the samples. The main focus was to evaluate the effect of added vegetable oil on the monitored parameters. The fats from the sample were extracted with a mixture of diethyl ether and petroleum ether. Fatty acids were converted to methyl esters by boron trifluoride-catalyzed acid esterification and subsequently identified by GC-FID. The analysis found a higher content of fatty acids in cheese analogues in comparison with the control sample, also the content of unsaturated fatty acids increased. The HS-SPME-GC-MS method was used for the identification and semi-quantification of volatile substances (aromatic substances). 56 volatile compounds were identified in the samples; The percentage of individual chemical groups differed significantly, the highest content was found in the control sample. Sensory evaluation was performed using a scale and a serial test. In all of monitored indicators (apparence, color, consistency, smell and taste) the control sample was evaluated as best. As for the analogues the taste and smell of used oils were detected, which was unpleasant for the evaluators. The obtained results show that the addition of vegetable oils increases the nutritional value of cheeses (higher content of unsaturated fatty acids), but reduces their sensory quality and overall consumer acceptability.
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Changes of sensory active substances during ripening of selected type of natural cheese
Sýkora, Michal ; Buňková, Leona (referee) ; Gregor,, Tomáš (referee) ; Buňka, František (advisor)
The presented dissertation is a study focused on the characterization of sensory quality, especially the flavour of model samples of natural cheeses. Attention is aimed to the composition and content of volatile (sensory active) substances as important markers of flavour and free/bound fatty acids as their precursors. The headspace solid phase microextraction in conjunction with gas chromatography with mass spectrometry was used to determine volatiles. For the determination of fatty acids, the lipids were isolated from the sample with a solvent mixture of diethyl ether and petroleum ether, followed by esterification using a methanolic solution of boron trifluoride as a catalyst and final analysis by gas chromatography with flame ionization detection. The experimental part was divided into two experiments; in experiment I, Moravský bochník type cheeses (45 % fat in dry matter., 60 % dry matter) were analysed, in experiment II, Edam type cheeses (45 % fat in dry matter, 50 % dry matter). Model samples of cheeses were made at Tomas Bata University in Zlín. For all samples, a classical mesophilic culture containing Lactococcus spp. and Leuconostoc spp. was used, this was always supplemented with a suitable monoculture of thermophilic bacteria; in the case of Moravský bochník cultures of Streptococcus thermophilus and Lactobacillus helveticus and in the case of Edam cheeses Lactobacillus casei and Lactobacillus plantarum. The essence of both experiments was to assess the influence of the used microbial cultures on the above-mentioned parameters, at the same time their changes during the ripening of the cheeses were monitored. The results showed that the addition of thermophilic cultures, as well as the maturation process did not affect the number of fatty acids or volatiles, but significant differences were found in their content. The content of bound fatty acids decreased during cheese ripening due to ongoing lipolytic changes while increasing the content of free fatty acids and their subsequent degradation to volatile substances, which ultimately contribute to the taste and aroma of the cheese. Ketones and acids were the most quantitatively present in all samples. During maturation, contrary to expectations, the content of identified volatiles also decreased. The addition of the thermophilic cultures didn’t have a clear effect and varied depending on the maturation phase. In the first phase, although they showed more pronounced lipolytic activity, the subsequent metabolic processes - the breakdown of free fatty acids into volatile substances, compensated for these differences. These results confirm a significant share of the basic mesophilic culture in the formation of volatile substances, in particular the flavour of cheeses.
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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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Influence of oil used on composition and sensory quality of cheese analogues
Buldra, Martin ; Mikulíková, Renata (referee) ; Vítová, Eva (advisor)
This paper deals with the manufacture and characterisation of cheese analogues, which are products, where the milk components are totally or partially replaced by non-milk components. Model samples, edam type cheese and the analogue containing hazelnut oil, were manufactured using the standard way at Brno Mendelu. The main parameters chosen to describe the quality of samples were free and bound fatty acids, volatile compounds and sensory quality. The main aim was to judge the influence of added hazelnut oil on mentioned parameters. For the identification and semiquantification of volatile compounds HS-SPME-GC-MS method was used. Fat extraction from sample was made with a mixture of two solvents (diethylether, petrolether), fatty acids were identified and quantified by GC-FID, with their former acid transesterification using methanolic solution of BF3 as a catalyst. For sensory analysis of the appearance, colour, texture, aroma, taste and overall acceptance of the sample descriptive scales and comparison with standard were used, the structure was observed by electron microscopy. The results show that addition of hazelnut oil affects the sensory properties, ripening process (higher amount of volatile compounds, faster lipolysis), nutrition value (higher amount of unsaturated fatty acids), and the stability of the product.
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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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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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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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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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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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