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Analysis of reaction products of selected beer components with nitrite.
Havránková, Lucie ; Vrzal, Tomáš (advisor) ; Olšovská, Jana (referee)
In this work, reactions of selected beer components (especially amino acids and phenolic compounds) with nitrite ions in an acidic environment and analysis of the resulting reaction products were performed using gas chromatography with mass spectrometric detection. Analysis of reaction products revealed 127 products containing one or more nitrogen atoms derived from nitrite in the molecule. Most of the products were found in ferulic acid, coumaric acid, 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone and 2-methoxy-4-vinylphenol, no products were found in the case of isoleucine, glutamic acid, phenylethanol and maltol.
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Verification of the authenticity of remains of 18th century medicinal products containing juniper or liquorice
Lener, Tomáš ; Nesměrák, Karel (advisor) ; Kubíčková, Anna (referee)
Three remains of historical pharmaceuticals from 18th century containing juniper (Rob juniperi, Lignum juniperi) or liquorice (Pulvis radicis liquiritiae) were analyzed by HPLC-MS method and their authenticity was verified using a chemotaxonomic approach. Current reference material was the source of chemotaxonomic markers and also a raw material for replication of Rob juniperi according to two period recepies. HPLC-MS method provided good results but wasinsufficienttoanalyzeLignumjuniperi.Therefore,GC-MSmethod wasalsousedto analyzethejunipersamplesand it provided sufficient results to prove the authenticity of both juniper samples. HPLC-MS method identified viridiflorin heptoside for the first time in juniper material, for which as well as for five liquorice markers ESI fragmentation spectra weremeasured and theirpossiblefragmentation mechanismwasproposed.Based on theobtained results, thepreparation ofhistorical samplesfrom the mentioned plants can beconfirmed. Key words: HPLC-MS, GC-MS,Chemotaxonomy, Juniper,Liquorice, Tandemmass spectrometry,Viridiflorin
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Production of agar candy with the addition of plant extract
Kameníková, Magda ; Gross, Michal (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the optimization of the production of jelly confectionery with agar as gelling agent, application of herbal extract to the prepared confectionery and subsequent identification of the content of aromatic active substances, characterization of phenolic content, antioxidant and antimicrobial activity and sensory quality. Calendula officinalis was selected as the source of the herbal extract, which is known for its high content of bioactive compounds. Determination of aromatic compounds was carried out by gas chromatography with mass detection, antioxidant activity by DPPH method, antimicrobial activity by diffusion method, determination of total phenolics by Folin-Ciocalteu method and sensory analysis was also carried out. Based on the sensory analysis, the optimum added amount of agar, extract and citric acid was determined. The additions of 1,25 % agar and 1 % acid were found to be optimal. The most sensory acceptable sample was the one without extract, while the sample with extract was the one with 4 % extract. The sample with Calendula extract of the above-mentioned optimal composition contained 14 identified aromatic compounds, of which guaiol, -cadinol and -muurolol were the most abundant; the total phenolic content was 464.30 ± 14.99 µgGAEg-1, and the antioxidant activity was determined to be 1.73 ± 0.01 mgTEACg-1 (or a radical quenching of 74.36 %). The antimicrobial effects of the above extract were tested against Gram-negative Escherichia coli and Gram-positive Bacillus cereus. The highest antimicrobial activity was exhibited by the extract alone and among the samples, it was the sample containing 4 % of the extract. The extract appeared to be more effective against B. cereus than E. coli. The results show that the content of extract in the samples increases their nutritional value and antimicrobial efficacy (increases the content of antioxidant and phenolic compounds).
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Possibilities of using fungal mycelium as a carrier of selected aromatic substances
Petržalová, Karolína ; Obračaj, Jan (referee) ; Hudečková, Helena (advisor)
This bachelor thesis focuses on the possibility of using fungal pellets made from the mycelium of Hericium erinaceus as carriers of aromatic substances. The chosen aromatic substance was wildlife repellent used in the application of scent detergents. The aim of the work was to determine the effectiveness of fungal pellets as a carrier for the active substance in wildlife repellent, the duration of the effect of the aromatic substance and the impact of the environment on the volatility of the aromatic substance. The chosen method for the determination of volatility was gas chromatography with mass detection. To determine the time of effectiveness, samples of fungal pellets were tested at given time intervals. From the results, it is evident that the fungal pellets are a suitable carrier for aromatic substances.
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Comparison of the microbial composition of English Blue Stilton cheese with related cheeses
Druláková, Tereza ; Vodička, Juraj (referee) ; Brázda, Václav (advisor)
This bachelor’s thesis focuses on the comparison of English blue-veined cheese Blue Stilton with commonly available cheeses of the same type, Roquefort and Niva, in terms of microbial composition, aromatic volatile content and also by sensory analysis. These methods distinguish the expensive Blue Stilton cheese from common and cheaper cheeses of the same type in the Czech Republic. The presence of 15 selected species of microorganisms was determined by RT-PCR. Three of them proved to be specific for Blue Stilton, specifically bacteria Brevibacterium linens and the yeasts Geotrichum candidum and Kluyveromyces lactis. Aromatic volatile compounds were determined by HS-SPME-GC-MS. Heptan-2-one, nonan-2-one, non-8-en-2-one and hexanoic and octanoic acids were the most important substances contributing to the aromatic profile of all cheeses. The cheeses can be distinguished according to the content of these substances in their aromatic profile or according to the amount of these substances in the individual samples. The sensory evaluation revealed that in most parameters like appearance, consistency and taste, Niva cheese was the most acceptable for Czech consumers while Blue Stilton was the most popular in the aroma category. On the basis of the obtained data, we are able to distinguish English Blue Stilton from other blue-veined cheeses according to specific microorganisms and the unique aromatic profile.
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Changes in the sensory quality and volatile compounds profile of smear ripened cheese during storage
Šebestová, Adéla ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the changes in sensory quality, volatile compounds profile and microbial profile of two smear ripened cheese, Olomoucké tvarůžky and Romadur, during their storage for four weeks. The sensory analysis, specifically the assessment of appearance, colour, texture, aroma and taste, showed differences between the two cheeses, which increased during storage (ripening). The greatest differences were observed in the assessment of taste, which improved during ageing for Olomoucké tvarůžky and deteriorated for Romadur. Analysis of volatile compounds by headspace solid-phase microextraction coupled with gas chromatography and mass detection revealed the presence of 57 substances belonging to 9 chemical groups. The composition of the cheese varied in terms of number and content of compounds, with alcohols, ketones and acids being the most abundant. In Romadur, esters predominated quantitatively, and in Olomoucké tvarůžky, sulphur compounds. The total amount of volatile substances in tvarůžky increased during maturation, whereas the opposite was true for Romadur. Microbial analysis showed the presence of a diverse microbiome on the surface of the cheese. There were slight differences between the microbial composition of the cheeses. There was no evidence of change in the microbiome during ripening. The qPCR method was used to identify the microorganisms present.
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Volatile substances in wines of minor varieties
Riedlová, Eliška ; Rychetský, Matěj (referee) ; Vítová, Eva (advisor)
The thesis focuses on the analysis and comparison of the aromatic profile of selected samples of white wines of minority varieties. For the experimental part, the varieties Neuburger and Kerner, originating from four wine regions: Slovácko, Znojmo, Velké Pavlovice, and Mikulov, were selected and analyzed. For the identification and quantification of volatile compounds, headspace solid-phase microextraction combined with gas chromatography and mass spektrometry detection was used. The linearity of the applied method was verified using 16 standards, which were subsequently used for quantification; the reliability coefficients R2 ranged from 0,9816 to 0,9995. A total of 62 volatile compounds were identified in the samples. Of all the identified compounds, 21 substances were selected as being present in the majority of the samples and constitued the largest contribution to the aroma of both varieties. In all samples, esters were predominant, but the composition of samples from different areas varied slightly.
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Freeze-dried fermented dairy products
Omelková, Viktorie ; Slavíková, Zuzana (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the production of yogurt, his lyophilization and reconstitution. By comparing all three forms of yoghurt in terms of sensory quality and volatile profile. The theoretical part deals with a characterization of fermented milk products, their production technology, lyophilization process, sensory quality and possibilities of determination of volatile compounds in yoghurt samples. In the experimental part of the thesis, a model sample of white yoghurt was produced and subsequently lyophilized. Freeze-dried yoghurt was first subjected to a consumer evaluation, where the general opinion of potential consumers on this type of product was investigated. The results show that it potentially could be applied on the market as a durable product. In the next phase, the lyophilized yoghurt was reconstituted again with the addition of water, from the point of view of a texture, the addition of approximately 30 % of the originally taken amount of water turned out to be optimal. The reconstituted yoghurt was then compared with the freshly made yoghurt, which was, as expected, rated as better, which could have contributed mainly to the positively rated aroma and the flavour. In reconstituted yoghurts, some evaluators detected an overly sour, bitter taste or an aftertaste of dried milk. Finally, all three types of yoghurt (fresh vs. freeze-dried vs. reconstituted) were compared in terms of volatile profile determined using solid phase microextraction combined with gas chromatography with mass detection. In total, 51 volatile substances were identified in all samples. The composition of the samples differed mainly in terms of the content of identified compounds, the most represented compounds were alcohols, followed by acids and ketones.
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Jelly candies with the addition of bilberry (Vaccinium myrtillus) extract
Knapovská, Pavlína ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
This thesis deals with the application of bilberry fruits (Vaccinium myrtillus) and their extract to jelly candies and the subsequent characterization of these candies in terms of volatile compounds, total phenolic compounds and anthocyanins, antioxidant activity and sensory quality. The volatiles were determined by headspace solid-phase microextraction coupled to gas chromatography with mass spectrometry and standard spectrophotometric methods were used for the determination of bioactive compounds. Total phenolic content was determined by the Folin-Ciocalteu method, antioxidant activity by the TEAC method and total anthocyanin content by pH differential analysis. The sensory quality of the samples was evaluated using unstructured graphical scales. The preparation of the bilberry extract was optimized on the basis of total phenolic content and the following conditions were selected as the optimal: a weight of 1000 grams of bilberries per litre of water, a temperature of 50 °C, and an extraction time of 2 hours. The optimum additions to candies were selected, by sensory analysis, as 25 wt. % of extract and 15 wt. % of bilberries. A total of 45 volatile compounds were identified in the candy with bilberry extract, the most abundant being (E)-9-hexadecen-1-ol (22,7 %), furfural (10,9 %) and 2-ethylhexan-1-ol (10,0 %). The total phenolic content was 1141 ± 11 gGAE · g-1, the antioxidant activity was 660 ± 66 gTE · g-1 and the total anthocyanin content was 418 ± 23 gC3G · g-1. A total of 40 volatile compounds were identified in the candy with bilberry and the most abundant were linalool (22,7 %), (E)-9-hexadecene-1-ol (16,1 %) and 2-ethylhexan-1-ol (8,4 %). The total phenolic content was 1735 ± 56 gGAE · g-1, the antioxidant activity was 1109 ± 32 gTE · g-1 and the total anthocyanin content was 745 ± 23 gC3G · g-1. With the addition of both the extract and the bilberries, the candies showed a significant increase in bioactive and volatile compounds content, and the colour and flavour of the enriched samples were positively evaluated, thus improving their overall acceptability.
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Determination of selected bioactive substances in grapes
Havlíková, Markéta ; Trachtová, Štěpánka (referee) ; Vítová, Eva (advisor)
The subject of this thesis was the determination of selected bioactive substances in grapes and the subsequent comparison of differences between the samples. Two fractions of grapes (skins and pulp with seeds) of 4 grape varieties - Hibernal, Johanniter, Riesling and Aurelius - were analysed. Two methods were used for the determination: for phenolic substances, high-performance liquid chromatography with mass spectrometry and for volatile substances, headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. For each of these methods, the optimal extraction technique was first selected and then used for the analysis of all samples. The linearity of the external standard method was also verified with a reliability coefficient R2 in the range of 0.9650-0.9989 for high-performance liquid chromatography with mass spectrometry and 0.8571-0.9999 for headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. 63 volatile and 9 phenolic compounds were identified in the samples. From these, specific compounds of grapes (20 volatile compounds and 5 phenolic compounds) were selected. On the basis of the amount of observed compounds, the two grape fractions and subsequently the grape varieties were compared with each other. There were differences in the content of selected compounds between grape fractions and across varieties, which could probably be due to the geographical origin of the samples.
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