|
|
Preparation and characterization of plant extracts for application to syrups
Šandová, Lucie ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
The aim of the diploma thesis was to produce herbal syrups from three selected herbs of the Lamiaceae family - Salvia officinalis, Melissa officinalis and Mentha piperita. First, extracts were prepared from these herbs by maceration in 25% of ethanol (60°C, 90 min). From the prepared herbal extracts, herbal syrups were made by mixing with syrup base (65% sucrose solution + lactic acid 2 g.l-1) in different ratios (2:1, 1:1, 1:2 - extract: base of the syrup). On the basis of sensory evaluation, a ratio of 1:1 was selected as optimal. The extracts and syrups produced were characterized in terms of volatile profile, phenolic content, antioxidant activity and antimicrobial activity. The produced syrups were also evaluated sensorially using scales, profile, and order test, and compared with similar commercial samples (Baťkovy sirupy s.r.o.). The HS-SPME-GC-MS method was used for the determination of volatile substances, the Folin-Cicalteu method for total phenolics, the TEAC method for antioxidant activity and the well and disc diffusion method for antimicrobial activity. 36 volatiles were found in model sage syrup, 29 in commercial syrup; 20 volatiles were found in model lemon balm syrup, 32 in commercial syrup; 25 volatiles were found in model mint syrup, 41 in commercial syrup. The quantitative distribution of the most important compounds in the commercial and manufactured syrups differed, with terpenes predominating in all samples. The content of phenolic compounds in syrups decreased in the order sage (570.1 mg.l-1) > lemon balm (378.9 mg.l-1) > mint (96.5 mg.l-1), antioxidant activity in the order lemon balm (332.0 µg.ml-1) > sage (185.6 µg.ml-1) > mint (115.8 µg.ml-1). Commercial syrups showed significantly higher phenolic compound content and antioxidant activity than manufactured syrups for all three herbs. In terms of sensory quality, mint syrup was considered the most palatable and sage syrup the least palatable (mint > lemon balm > sage); only in the case of lemon balm was the manufactured syrup considered better, more palatable than the commercial sample. It was reasonably liquid, clear of a pleasant colour, with a distinctly sweet, slightly herbaceous taste and a pleasant aroma.
|
|
|
Influence of aroma compounds on sensory quality of sweets
Motúzová, Eliška ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This master´s thesis is focused on determination of aroma active compounds in non-chocolate sweets and their influence on sensory quality/flavour. The theoretical part describes production of non-chocolate sweets, characterizes aroma active compounds including allergenic ones, method for their determination by solid-phase microextraction and gas chromatography with mass detection. For experimental part were used as model samples gummy candies purchrased in regular market. Four flavors were used, specifically yellow (lemon), green (apple), red (strawberry) and orange (orange). The HS-SPME-GC-MS method was used to identify volatile aroma active compounds. To evalutate the sensory quality were used scales, a profile test, and a time course evaluation. Owerall 120 volatille compounds were identified including 8 allergens.
|
|
|
Production and characterization of non-chocolate sweets with the addition of plant extracts
Knapovská, Pavlína ; Nábělek, Jakub (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the production and characterization of plant extracts of green tea (Camellia sinensis) and sea buckthorn (Hippophae rhamnoides) and non-chocolate sweets – hard candies with the addition of plant extracts. These plants are characterized by a high content of bioactive substances, upon which the prepared extracts and candies were characterised. Determination of volatile substances by HSSPME-GC-MS, antioxidant activity by method with ABTS, determination of total phenols by Folin-Ciocalteu method and sensory analysis were performed. The produced sweets were then compared with similar commercial products. A total of 6 volatile substances were identified in the sample of hard candy with the addition of green tea extract, the antioxidant activity of the sample was determined to be 253,3 ± 0,9 µgml–1 and the total phenolic content was determined to be 0,49 ± 0,02 mgGAEg–1 per 1 g of candy. A total of 8 volatile substances were identified in the hard candy with the addition of sea buckthorn extract, the antioxidant activity of the sample was determined to be 206 ± 3 µgml–1, the total phenolic content was determined to be 0,51 ± 0,04 mgGAEg–1 per 1 g of candy. The obtained results show that the addition of extracts increases the nutritional value (higher antioxidant activity, higher content of phenolic compounds) of produced candy; from a sensory point of view, however, only samples with green tea were evaluated positively, the addition of sea buckthorn extract was not very attractive for consumers, they considered sweets with sea buckthorn to be too bitter.
|
|
|
Obtaining and complex charaterization of Aronia spp. extracts
Seidlová, Kateřina ; Zemanová, Jana (referee) ; Veselá, Mária (advisor)
Aronia (Aronia melanocarpa) is a berry fruit with distinctive sensory characteristics and health-promoting properties. Polyphenols are the main bioactive compounds found in aronia including natural pigments – anthocyanins. Bioactive compounds are usually obtained from natural materials by extraction, in this work, two methods of extraction were compared – maceration and PHWE. Based on the total phenolic content, maceration was chosen as a more suitable method and then was optimized with statistical model – Design of Experiment. Optimal conditions were set to temperature of 30 °C, extraction agent 50 % ethanol, solid-solvent ratio 10 g per 50 ml and time of extraction for 30 minutes. Extract obtained under these conditions was characterised by total phenolic content – 1441 ± 90 mg/100 g DW, total anthocyanin content 943 ± 8 mg/100 g DW and antioxidation activity by ABTS 24,78 ± 0,09 molTE/g. In total of 25 volatile compounds were indentified in the optimal extract with content > 0,5 %. Major part created aldehydes and esters, with the main compounds being benzaldehyde (32,25 %) and methyl hexanoate (21,37 %).
|
|
|
Preparation and characterization of Echinacea extracts
Pallová, Jana ; Veselá, Mária (referee) ; Vítová, Eva (advisor)
Echinacea purpurea is a rich source of biologically active compounds, which are attributed to several therapeutic effects. This thesis is focused on the optimization of the extraction process, considered these substances. Maceration was chosen as a type of extraction, due to its simplicity. The Optimal conditions were solid-solvent ratio 1: 5, 40% ethanol, 60 °C, 60 minutes. An extract from the dried flowers of Echinacea purpurea was prepared by this optimized process. The content of total phenolic compounds was set on 365.18 ± 3.51 [mg_GAEl^(-1)] and the antioxidant activity was 507.50 ± 6.89 [mg_TEACl^(-1)]. The percentage of radical scavenging activity ABTS•+ was 95.45 ± 1.30. The antimicrobial activity of the extract was tested against 3 microorganisms – Escherichia coli, Bacillus cereus and Candida glabrata. There was not detected inhibitory effect on the growth of microorganisms. In a total, 39 volatile compounds were identified, and the biggest group were represented sesquiterpenes (70.9%). The obtained results confirm that Echinacea extract has antioxidant activity and contains several interesting aromatic substances, In the future, it can be used as a natural resource of nutritionally and sensory valuable compounds, e.g., into various foods and delicacies.
|
|
|
Study of volatile compounds of chocolate depending on geographical origin of cocoa beans
Kubínová, Martina ; Kovalčík, Adriána (referee) ; Vítová, Eva (advisor)
Diploma thesis is focused on cocoa beans volatile compounds from various region (Tanzania, Haiti, Ecuador, Madagascar and Peru) and chocolate bars made of them. The main aim was to judge diferences between samples according to geographycal origin. At the same time, samples of chocolates with different content of cocoa solids (50%, 70% „organic“, 70%, 78%, 90%) and a sample of cocoa powder from the common market were analyzed. Volatiles were identified and semiquantified by HS-SPME-GC-MS. A total of 86 volatile substances were identified, they were divided into 7 groups according to the nature of the odor: fruit tones (17), nut and chocolate (16), astringent and sour (12), unspecified (14), sweet nad honey (10), earthy (9) and floral (8). The data were transformed into a 2D graph by analyzing the main component according to selected distinguishing varibles. The difference in the volatile substances of cocoa beans depending on the geographical origin were confirmed using principal component analysis.
|
|
|
Accuracy of the method for assessment of allergenic aroma compounds
Rychetský, Matěj ; Hrstka, Miroslav (referee) ; Vítová, Eva (advisor)
This bachelor thesis deals with the verification of the accurancy of the method for determination of potentially allergenic substances in confectionery. In the theoretical part the synthetic and natural fragrances, which are present in foodstuffs are described. Furthermore, the method of solid phase microextraction in connection with gas chromatography with mass spectrometry, which was used in the measurement, is briefly characterized. Finally, the basic criteria measured in the validation of the analytical method are described. In the experimental part, the repeatability and reproducibility of the HS-SPME-GC-MS method for the determination of potentially allergenic substances in candy samples was verified. It was found by the measurement that the used method is suitable for qualitative determination (based on retention times), but the method shows minor inaccurancies in quantitative determination (determination based on peaks area) and it will be improved in following experiments.
|
|
|
Volatile profile of unusual type of fruit (Asimina triloba)
Pallová, Jana ; Šimíčková, Adéla (referee) ; Vítová, Eva (advisor)
The purpose of this bachelor thesis is to determine aroma active substances in an unusual fruit - pawpaw (Asimina triloba). The theoretical part consists of a general description of the plant and characterization of its characteristics, composition and use. Furthermore, the issue of aroma active substances are processed as well as the method of their determination by solid-phase microextraction in connection with gas chromatography and mass spectrometry. The experimental part deals with the identification and quantification of aroma active substances using the selected method HS-SPME-GC-MS in three varieties - PA-Golden, Rebecca's Gold and NC-1. Differences in the number and content of volatile substances were found among the varieties. The lowest values were PA-Golden. In total, 105 compounds have been identified, including 7 aldehydes, 15 alcohols, 58 esters, 6 ketones, 4 lactones, 1 nitrogen compound, 1 alkane, 4 acids, 2 phenols, 1 alkenes, 4 terpenoids, and 2 other compounds.
|
|
|
Study of volatile hydrocarbon decomposition in non-thermal plasma of surface discharge at atmoapheric pressure
Věrná, Jana ; Rašková, Zuzana (referee) ; Kozáková, Zdenka (advisor)
The main goal of this thesis was to study plasma generated by surface discharge and its application in volatile organic compound destruction. Introduction of this thesis deals with the issue of volatile organic compound. The term of volatile organic compound was defined and explained. Summary of the most important sources of volatile organic compound emissions and possible technics for their elimination was presented. This thesis drew attention on negative aspects of volatile organic compounds on human organism and on the whole environment. The problems of surface discharge and its possible application in various branches are known only few years therefore construction of plasma reactor itself was the first independent step of this work. The plasma reactor was consisted of electrode, which was created from the series of metal stripes each other separated by dielectric barrier. On the surface of the electrode, discharge was regulated and distributed. For the reason of technical limits experiment time was limited up to one minute. The experimental part describes reactor for surface discharge and other parts of apparatus in which degradation volatile organic compound was carried out. Nitrogen was used as carrier gas and it was mixed with air before entering into the reactor. Samples of compounds after degradation process were taken from reactor for the subsequent analysis. Analysis of the products proceeded in a gas chromatogram linked to mass spectrometer. The decomposition products were adsorbed in the SPME filaments or in sorption tubes. The decomposition products were analysed also through the mean of Testo 350 M/XL. This apparatus provided the information on the concentration of small molecules such as CO, H2, NO, NO2 and CxHy Hexane, cyclohexane and xylene were used as VOC examples. Analysis of GC-MS showed decomposition products of hexane, cyclohexane and xylene. The decomposition products were especially various alcohols, ketones, aldehydes and benzene compounds. The apparatus Testo 350 M/XL was unable to detect any CxHy, only large quantity of NO2. This thesis was further focused on possible factors which could have an influence on degradation of compounds, for example input power or different flow of oxygen. It was found that increasing power declined the removal efficiency. The maximum removal efficiency was 87 % for degradation of hexane at the lowest input power. Next part of this thesis was focused on diagnostics of plasma generated in the surface discharge form. The optical emission spectroscopy has been chosen as the best method for plasma characterisation. By this method, various important discharge parameters can be determined, e.g. vibration and rotation temperature. The obtained numeric value of rotation temperature was 840±80 K and vibration temperature was 1880±140 K. The obtained results may be used as a fundament for further study of VOC decomposition in surface discharge.
|
|
|
Obtaining and complex charaterization of Plectranthus spp. extracts
Boboková, Alexandra ; Saláková, Alena (referee) ; Vítová, Eva (advisor)
Plectranthus amboinicus is a herb that was found to have a lot of bioactive compounds, most of them are polyfenolic compounds. Extraction is neccesary to obtain bioactive compounds and to use them subsequently in food or cosmetic industry. Three methods of extraxtion – maceraction, PHWE and PFE, were used in this study. The best yield of extracted polyfenols was observed by maceration. Maceration was, in the next step, optimized using mathematical statistical method of planned experiment (DOE). The optimal conditions found for extraction were: temperature 60 °C, solvent 40% ethanol, time 90 minutes, solid-solvent ratio 1:10. Total phenolic compunds content in this extract was 0,18 ± 0,05 mgGAE·ml-1, which means 1,83 ± 0,53 mgGAE·g-1 of plant. The antioxidant activity was 148,69 ± 26,92 gTEACml-1. Percentage of radical scavenging activity ABTS•+ was 30,03 ± 5,44 %. Further, 27 of volatile aroma compounds were identified in optimal extract, the most important were: -selinene (16,67 %), trans--bergamotene (14,22 %), caryophyllene (14,11 %), 3-carene (8,22 %), -copaene (7,55 %), -terpinene (6,28 %), humulene (5,87 %), cadina-1(10)-4-diene (5,19 %).
|
guest ::
