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Determination of antimicrobial and antioxidant activity of selected herbal extracts
Čaková, Adriana ; Němcová, Andrea (referee) ; Vítová, Eva (advisor)
Tetradenia spp. is herb naturally growing in Africa and is part of family called Lamiaceae. The herb is used in traditional medicine to cure malaria, angina or as treatment for tropical skin diseases. Maceration was chosen from number of extraction methods, to obtain bioactive compounds from this plant. Optimization was performed with aim to retrieve as much of bioactive compounds as possible. Optimal conditions chosen were: temperature 60 °C, extraction time 40 minutes, solvent 40% ethanol and solid-solvent ratio 1:5. In total 63 aromatic active compounds were found in optimal extract. Terpenes were the most abundant (88,60 %), from them oxygenated monoterpenes (55,65 %) and monoterpenes (29,52 %). Compounds with highest percentage quantity were camphor (51,76 %), cis--ocimene (8,17 %), 3-octyl acetate (7,71 %), trans--ocimene (6,76 %), -terpinene (4,93 %), o-cymene (3,81 %), terpinolene (1,33 %), limonene (1,33 %), camphene (1,19 %) and borneol (1,20 %). Further, total phenolic content was 0,31 ± 0,02 mgGAEml-1, which equals 1,52 ± 0,11 mgGAEg-1 of plant. Antioxidant activity was 417,56 ± 32,84 gTEACml-1 and percentage of radical scavenging activity ABTS•+ was 88,99 ± 7,00 %. Finally antimicrobial activity was determined against bacteria Bacillus cereus, Escherichia coli and yeast Candida glabrata. Against E. coli and C. glabrata there was no inhibition exhibited. Against B. cereus there was seen mild inhibition activity. The results confirm that Tetradenia spp. contain a number of interesting aroma active compounds, which shows antioxidant and antimicrobial activity. The herb has a good potential as natural source of nutritious and sensory active compounds to be used into various foods.
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Changes of aroma active compounds during production of model cheese
Školová, Dominika ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
The aim of the work was identification of aroma active compounds in Moravský bochník cheese type, than discuss their changes during ripening and consider influence of aplication different rates of microbial cultures on number of volatile compounds. SPME-GC-MS was used for identification of volatile compounds. In total, 148 of volatile compounds were identified and 82 of them are considered as aroma active compounds. Three microbial cultures (their combination with predominant thermophilic or mesophilic culture) were used for making samples. The influence of predominant thermophilic/mesophilic culture on number of volatile compounds was not proved. From the point of view of sensory quality, combinations with predominant mesophilic culture proved to be more successful. During ripening, the number of identified compounds was reduced in all the combinations of cultures studied. The optimal time for ripening seems to be three months.
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Beer bioflavouring by dry hopping using czech cultivars of hops
Gajdušek, Martin ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with the influence of dry hopping on selected analytical and sensory properties of beer. The effect of dry hopping was observed using Czech hop varieties Kazbek and Uran, which were added to the wort during the main fermentation phase in doses of 3 and 6 gdm-3. The contact time of hops with wort was 3, 6 and 9 days. The experimental part describes the technology of preparation of the reference beer, in which dry hopping were subsequently performed. A parallel measurement was performed on each sample. In terms of the basic parameters of beer, the effect of dry hopping, especially its length, on the ethanol content was observed. With a longer period of dry hopping, the concentration of ethanol in beer increased. The higher alcohol concentration was also associated with a decrease in the apparent extract. In terms of color and pH of beer, the effect of dry hopping has not been proven. Elemental analysis performed by optical emission spectrometry with inductively coupled plasma revealed an increase in the concentration of calcium, magnesium, and iron due to dry hopping. No statistically significant difference was observed for manganese and barium compared to the reference. In terms of bitterness, a significant increase was identified in dry hopped beers compared to the reference, the value being dependent on the dose of hops used. The effect of the hop variety has not been proved. Concentrations of organic acids determined by ion-exchange chromatography with a conductivity detector were affected by dry hopping only in the case of lactic acid and acetic acid. An increase in lactic acid was observed compared to the reference, also related to the degree of fermentation. While in the acetic acid content the hop samples showed a lower concentration than the reference sample. The concentrations of myrcene, humulene and geraniol were determined by gas chromatography with a mass detector. These are volatile components of hop essential oils. Dry hopped samples recorded significantly higher concentrations of all aromatic substances compared to the reference. In terms of hop time, the highest concentrations were shown by samples hopped for three days. The results of the sensory analysis show that the overall best rated sample is a sample hopped with the Kazbek variety with a dose of 3 gdm-3 for three days. Beer which was dry hopped for the shortest time also showed the lowest intensity of bitterness, which was perceived positively.
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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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The content of aroma active compounds in sweets
Paulišová, Sabina ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This bachelor thesis focuses on identification of aroma active compounds in selected samples of non-chocolate sweets. Based on the results obtained, the aromatic profile of the individual samples is compared. The theoretical part deals with aroma active compounds, legislation and technology of manufacturing non-chocolate sweets. Further experimental technique and the methods used in practical part, namely solid phase microextraction and gas chromatography with mass spectrometry detection are presented. In the experimental part volatile aroma active substances were identified in green colored jelly candy samples available in the common market. For this purpose, the HS-SPME-GC-MS method was used. The individual samples differed in type and number of volatile compounds, depending on the manufacturer. In total 72 different compounds, including 11 aldehydes, 14 alcohols, 27 esters, 1 heterocycle, 8 carboxylic acids, 6 ketones, 4 hydrocarbons and 1 sulfur compound were found.
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Analysis of sensorially active substances contained herbal extracts
Koloničná, Markéta ; Vítová, Eva (referee) ; Mikulíková, Renata (advisor)
The peppermint (Mentha piperita), the salvia (Salvia officinalis), the lemon balm (Melissa oficinalis), the camomile (Matricaria chamomilla) and the valerian (Valeriana officinalis) are herbs with healing effects. Their ethanol extracts are used for food fortification or in a cosmetic industry. Substances contained in herbal extracts were analyzed in this thesis. The extracts were prepared by maceration. Next, they were analyzed by using a gas chromatography and a mass spectrometry. The aim of this thesis was an optimalization of the method used for the analysis of sensorially active substances. Then, herbal extracts were analyzed and concentration of sensorially active substances was determined.
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Substances present in cumin oils
Suchánková, Renáta ; Boško, Rastislav (referee) ; Svoboda, Zdeněk (advisor)
The bachelor thesis is devoted to important substances in caraway oil. The determination of substances was performed in the laboratories of the Brno Institute of Brewing and Malting, a.s. It is divided into theoretical and experimental part with results and their discussion. The theoretical part describes caraway (Carum carvi), its use and composition of caraway oil, including the possibility of its use. The practical part deals with the identification and determination of content substances in caraway essential oils by the method of gas chromatography and mass spectrophotometry (GC-MS). It also includes a comparison of the content of different caraway essential oils.
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Characterization of the genus Plectrantus for use in the food industry
Chmelová, Nikola ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis was to determine the optimal extraction conditions for obtaining an extract from the plant Plectranthus amboinicus. Plectranthus amboinicus is an aromatic herb of the Lamiaceae family containing a large number of bioactive compounds. Because of this, it has a number of biological effects – antimicrobial, anti-inflammatory, antioxidant, analgesic, etc. To maintain the maximum of sensory and nutritionally valuable components of P. amboinicus, a simple maceration of fresh chopped herb was chosen. Maceration was performed under the following conditions: 40 minutes at 40 ° C, solvent 40% ethanol, weight 20 g of herb per 100 ml of solvent. The extract prepared under these optimal conditions was comprehensively characterized in terms of the content of total polyphenols, their concentration was determined to 0,08 ± 0,02 mgGEA·ml-1, which corresponds to 0,40 ± 0,07 mgGEA·g-1 of the plant. The antioxidant activity of the extract was 241,24 ± 29,24 µgTEAC·ml-1 and the radical scavenging activity of ABTS•+ was determined to be 49,29 ± 5,97 %. The antimicrobial activity was verified by the agar well diffusion method. Two types of bacteria were selected for the determination – gram-positive Bacillus cereus, gram-negative Escherichia coli and yeast Candida glabrata. The results showed that the extracts have the highest antimicrobial activity against B. cereus. There were 64 volatile aromatic compounds identified in the extract, with monoterpenes and sesquiterpenes dominating. The obtained results confirm that P. amboinicus, or its prepared extract, has a good potential for use as a new and non-traditional flavor in various foods and delicacies, which can also increase their nutritional value.
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Study of the aroma profile of selected varieties of Moravian wines
Gross, Michal ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
The subject of this thesis was the determination of the profile of volatile aromatic compounds of varietal wines and the subsequent statistical analysis, aiming to find varietal markers of selected varieties – individual substances, their typical contents, mutual correlations. The HS-SPME-GC-MS technique was used to determine the aromatic profile. The main focus of this work was the analysis of the varieties Pálava, Hibernal, Johanniter and Solaris. The data obtained were statistically processed using descriptive and multivariate statistical methods. On the basis of these analyses, models were developed which, from the contents of 14 selected compounds of the aromatic profile, allow the Piwi varieties Hibernal, Johanniter and Solaris to be distinguished from each other and from the Pálava variety and, for the Pálava variety wines, to determine their origin in the Znojmo or Mikulov wine sub-region.
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Aroma active compounds of selected types of herbs
Škutová, Pavla ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the identification of aroma active compounds in medicinal herbs. The group consists of 5 types of herbs: lemon balm (Melissa officinalis), pot marigold (Calendula officinalis), clary sage (Salvia sclarea), milk thistle (Silybum marianum), goat’s rue (Galega officinalis). These plants are known for their positive effects in folk medicine. The SPME-GC-MS method was chosen to characterize the fragrances. During the identification of volatile compounds, emphasis was put on suspected fragrance allergens listed in EC Regulation 1223/2009 in Annex III. Overall 106 compounds were identified together with 8 allergens in lemon balm, pot marigold contained 104 compounds with 7 allergens included, 82 compounds including 5 allergens in clary sage, 73 compounds were identified in milk thistle including 6 allergens and 110 compounds with 9 allergens included in goat’s rue.
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