|
|
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
|
|
|
Study of volatile hydrocarbon decomposition in non-thermal plasma of gliding arc at atmospheric pressure
Töröková, Lucie ; Rašková, Zuzana (referee) ; Kozáková, Zdenka (advisor)
Diploma thesis deals with gliding arc discharge in non-equilibrium plasma, its properties and usage for dissociation of volatile organic compounds. Plasma techniques create a perspective alternative to classical methods such as adsorption, biofilters, thermal processes, freezing and condensation. The method used for analysis of dissociation products is described in the theoretical part as well. Method is gas chromatography and it is combined with mass spectroscopy. The experimental part contains the overall description of GlidArc reactor where volatile organic compounds were dissociated. The volatile organic compound is brought into the reactor from the reservoir by carrier gas (nitrogen); synthetic air was used as working gas. The reactor is connected to the device for sampling. This device has several openings for sampling by SPME fibre method, sorption tubes method and a special opening for probe entry from the device Testo 350 M/XL, which enables instant analysis of low-molecular compounds. GC-MS was used for determination of high-molecular products of dissociation. Products sorbed on SPME fibres were analysed directly, compounds sorbed by active carbon were extracted by carbon disulphide. Samples obtained using SPME fibres were analysed. The major products of the dissociaton were found due to this analysis, those major products are in the case of hexane: pentanal, 4 methyl-3-pentanal, 2-butoxy-ethanol, pentane a 2-hexene. Major products detected when dissociating cyclohexane were: l,3-dimethyl-butane, propanal, cyklohexanone, 5-hexenal a 2-pentyn-1-ol. Major products of xylene dissociation were methyl-benzene, benzaldehyde, 4-methyl-benzaldehyde, 1-nitroethyl-benzene a benzenmethanol. After analysis obtained using sorption tubes showed that mainly the dissociated compound was sorbed, but the products of the dissociation were presented in too low concentration for an adequate analysis. For that reason the sorption tubes were used only for quantitative determination of the compounds depending on the power supply. The dependence of the dissociation of the compounds on the power supply was observed using SPME fibres which were used for quantitative determination. The Results obtained by both obtained techniques were almost in accordance. Speaking of low-molecular compounds, dissociation of all compounds gave the same products, i.e. carbon dioxide, hydrogen, nitrogen oxide, nitrogen dioxide and water. The results show that the dissociation of VOC gives - besides many potentially dangerous dissociation products - significant amounts of nitrogen oxides which is harmful to the environment. Hence it is necessary to be concerned with problems studied in the future mainly with respect to limitation of NOx generation. It will be possible to optimalize the conditions of the VOC dissociation on the basis of future kinetic analysis.
|
|
|
Characterisation of elderberry fruits
Christovová, Silvia ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This master's thesis deals with the characterization of elderberry fruit (Sambucus nigra L.) with emphasis on the aroma active compounds (AAC) and vitamin C (ascorbic acid (AA), dehydroascorbic acid (DHA)). The theoretical part gives a brief outlook on the chemical composition and attributes of Sambucus berries, its healing properties and the means of processing. The rest of the theoretical part thoroughly examines the AAC and vitamin C. The suitable assessment methods are also discussed. The experimental part of the work consists of two main tasks. The first one was to assess the aroma profile of Sambucus berries using the HS-SPME-GC-FID. 18 samples were examined (the wild elderberry and 17 cultivated varieties). In total, 24 different volatile aroma active compounds were identified and quantified, 12 of which belonged to alcohols, 5 to aldehydes, 4 to esters, 1 to acids and 2 “other” compounds (linalool and -damascenone). The chemical composition of the individual samples was not uniform; no single sample contained all of the identified compounds. The second task was to assess the total vitamin C content (the sum of DHA and AA) using the HPLC. For the purpose of reducing DHA to AA three reducing agents were examined (DTT, TCEP and L-cysteine) at two different pH levels (7 and 4). TCEP at pH 4 turned out to be most efficient and was subsequently applied on the samples of 5 selected elderberry varieties. The measured vitamin C content was within the range of 5,1 – 13,0 mg per 100 g of fruit.
|
|
|
The assessment of aroma active compounds in cheeses
Ryglová, Hana ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This work deals with aroma active compounds of Edam cheese, i.e. natural hard cheese with low heat curd. Aroma active compounds contribute to overal aroma of cheese. They are volatile compounds, which include alcohols, aldehydes, ketones, fatty acids, esters, lactones, terpenes etc. These compounds were identified and quantified using SPME/GC/FID method in the model samples of Edam cheese, produced at Tomas Bata University in Zlin. In total 18 volatile compounds were identified, 3 aldehydes, 4 ketones, 7 alcohols, 1 ester and 3 acids. Differences in number of compounds identified, as well as in the contents of them, were found between samples. Low number of compounds and also their low total content correspond to the initial phase of cheese ripening.
|
|
|
Sensorial and analytical evaluation of cheese analoques flavour
Brabcová, Lenka ; Horváthová,, Viera (referee) ; Vítová, Eva (advisor)
The aim of the diploma thesis was to determine the influence of different kinds of fats on the content of aromatic active compounds and total flavour of processed cheese analogues. Samples of the cheese were produced by Tomas Bata University in Zlín from concentrated milk fat, butter, palm fat, coconut fat and sunflower oil. The aromatic compounds were isolated from samples of fats and processed cheese analogues via HS-SPME-GC method. A fibre with polar stationary phase CAR/PDMS was used for capturing of aromatic active compounds. In different contents, total of 32 aromatic compounds were determined. The cheese from concentrated milk fat and butter had the highest content and cheese from sunflower oil had the lowest. For determination of acceptability and flavour, the cheese analogues were sensory evaluated at the same time. Ordinal test, evaluation via scale and profile test were used. Cheese made from concentrated milk fat and coconut fat were always evaluated as the best, cheese made from sunflower oil were evaluated as the worst. Finally results between SPME-GC and sensory analysis were compared. It was stated that the kind of fat used for production of processed cheese analogues significantly influences the content of aromatic compounds and thus influences flavour of the cheese analogues.
|
|
|
Application of herbal extract to non-chocolate jelly sweets
Phi, Lan Anh ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
This master’s thesis focuses on optimization of application of herbal extracts and powder into jelly sweets and comparing them to commercial products with a same flavour. Prepared and commercial samples were then characterized in terms of volatile substances, total phenolic content, antioxidant activity and sensory quality. Volatile compounds were determined by HS-SPME-GC-MS method, a verification of validation parameters (limit of detection and quantification, repeatability, reproducibility, retention time, retention index) was part of the thesis. The total phenolic content was determined by Folin-Cicalteu’s spectrophotometric method, antioxidant activity by TEAC method and sensory quality by sensory analysis. Optimal amount of extracts and powders were selected based on the sensory analysis. For the preparation of extracts and powders were used aromatic plants lemon balm (Melissa officinalis) and ginger (Zingiber officinale). Optimal amount of extract addition was the concentration 15 %, by the next sensory analysis was determined 1 % addition of the powder for both herbs. There were 32 volatile compounds identified in a model lemon balm jelly, which of 4 were allergens (linalool, Z and E isomer of citral, citronellol, Z and E isomer of geraniol). Total phenolic content in the sample was 755,5 ± 14,3 gGAE g–1 and antioxidant activity was determined on a value 2,73 ± 0,13 10–3 mmolTE g–1. Commercial lemon balm sample contained 54 aromatic compounds from which were 5 allergens – limonene, linalool, Z and E isomer of citral, citronellol, Z and E isomer of geraniol. Total phenolic content was 695,5 ± 9,8 gGAE g–1 and antioxidant activity was 2,67 ± 0,05 10–3 mmolTE g–1. There were 26 volatile compounds identified in the model ginger jelly, which of 4 were allergens (linalool, Z and E isomer of citral, citronellol, (Z)-geraniol). Total phenolic content in the sample was 511,0 ± 12,3 gGAE g–1 and antioxidant activity was determined on a value 1,87 ± 0,16 10–3 mmolTE g–1. The first commercial ginger sample contained 55 aromatic compounds and 4 of them were allergens (limonene, linalool, citronellol, (E)-geraniol). Total phenolic content in the sample was 224,3 ± 20,2 gGAE g–1 and antioxidant activity was determined on a value 0,95 ± 0,24 10–3 mmolTE g–1. The second commercial sample contained 32 volatile compounds, which of were 4 allergens – limonene, linalool, Z and E isomer of citral and (E)-geraniol. Total phenolic content was 569,9 ± 23,2 gGAE g–1 and antioxidant activity of the sample was 3,48 ± 0,08 10–3 mmolTE g–1. In terms of sensory properties, the prepared samples which had balanced sweet and sour taste with pleasurable optimal herbal taste, were preferred by evaluators.
|
|
|
Comparison of aroma profile of fruit distillates
Koubek, Miroslav ; Veselá, Mária (referee) ; Vítová, Eva (advisor)
This master thesis deals with the assessment of aroma active compounds in fruit spirits. In the theoretical part the production technology of fruit spirits from raw materials to final product is described. Furthermore, aroma active substances are characterized, and the method for their determination by solid phase microextraction and gas chromatography with mass spectrometry is described. The aim of the experimental part was the identification of volatile substances in different kinds of fruit spirits. Aromatic compounds were identified by the SPME-GC-MS. Domestic fruit spirits obtained from private growers were used as model samples. The differences in the number and type of volatile compounds were found between the samples. Overall 53 volatile compounds were identified. These were composed of 25 esters, 9 alcohols, 5 aldehydes, 4 alkenes, 2 ketones, 1 carboxylic acid and 7 other compounds.
|
|
|
Determination of selected musk compounds in biotic samples
Blahová, Eliška ; Čáslavský, Josef (referee) ; Vávrová, Milada (advisor)
Musk compounds (MUSK) or synthetic fragrances are organic substances commonly used as fragrant constituents of detergents, soaps, cosmetics, personal care products, industrial and in-house cleaning agents, industrial plasticizers, chewing tobacco and fresheners. The big attention is pushed ahead studying these compounds, their fate in different parts of ecosystems and studying their characteristics at present, because musks infiltrate many environmental components, particularly aquatic and marine ecosystems, through their large application and their ability to be perzistant. This diploma thesis was focused on four synthetic “classical” fragrances used over the world. The aim of this study was to perform a method optimisation for the determination of selected fragrances in biotic matrix. There was made an evalution of ability of selected water treatment plant to clear away musks from water, these results were used for evaluating contamination measurement of aquatic ecosystem. The identification and quantification of analytes was carried out by high resolution gas chromatography - mass spectrometry (HRGC/MS).
|
|
|
The use of biochar as a sorption material for the removal of synthetic fragrances from water
Kašparová, Jarmila ; Zlámalová Gargošová, Helena (referee) ; Mravcová, Ludmila (advisor)
Synthetic fragrances (musk) are artificially produced organic compounds. It is used as fragrance ingredient in personal care products. Substances from this group have the ability to withstand the cleaning process in wastewater treatment plants. The physico-chemical properties of musk compounds cause their accumulation in the living and non-living components of the ecosystem, where they behave as persistent pollutants. The adsorption process is considered to be one of the most widely used separation and purification processes. The adsorption processes of a solution of sixteen synthetic fragrances took place with biochar and activated carbon. Solid phase microextraction (SPME) was used as a method for extracting analytes. Gas chromatography coupled with mass spectrometry (GC-MS) was applied for final analysis, time of flight analyzer was used as detector. The data were fitted with adsorption isotherms.
|
|
|
Determination of residual substances from the preparation of colloidal systems based on biopolymers
Borůvková, Tereza ; Vávrová, Milada (referee) ; Mravec, Filip (advisor)
Volatile organic compounds could be isolated and concentrated from liquid solution using methods, which are based on analysis of equilibrium gas phase, because of their volatility. The aim of this bachelor´s thesis is determination the amount of residual tert-butanol, belonging to volatile organic compounds, in the samples after lyophilisation. Samples were prepared by mixing hydrofobic sonde and hydrofilic hyaluronan. For mixing these components it is necessary to add organic solvent tert-butanol, which ensures stable environment. Thanks to its presence mixing of probe and hyaluronan occurs. Consecutive lyopfilisation of the sample leads to the disruption of a water cover of hyaluronan and nonpolar hydrogen atoms, which are hidden in it, can interact with hydrofobic probe. Bonding the probe is important in oncology, where this fact could be used in targeted distribution of pharmaceuticals. However presence of tert-butanol is unacceptable in the final product, mainly in medical applications. The object this study is the minimization of residual tert-butanol amount in final lyophilised cake. The method of equilibrium gas phase analysis (static Head-Space) by gas chromatography with flame ionization detection (GC/FID) was used for the determination of its content.
|
guest ::
