National Repository of Grey Literature 247 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Determination of physico-chemical stability of toothpastes
Posztósová, Gyöngyi ; Vítová, Eva (referee) ; Němcová, Andrea (advisor)
This diploma thesis is focused on determining the physico-chemical stability of toothpastes. It is divided into theoretical and practical part. The theoretical part of the work deals with toothpastes, their short history and composition. Stability studies and methods of stability analysis are described below. In the practical part were performed long-term and accelerated stability studies on anhydrous toothpastes, on water-based toothpastes and on toothpastes based on sodium bicarbonate. The physical stability of the products was evaluated by monitoring the appearance and color visually and odor sensory, the pH value using a pH meter and the viscosity with a rotational viscometer. Chemical stability was monitored by determining the free fluorine content by ion chromatography and by ion-selective electrode, total phosphates and potassium also by ion chromatography, sodium bicarbonate by titration, soluble zinc by atomic absorption spectrometry and water activity was also monitored.
Biologically active substances of chokeberry (Aronia spp.)
Palkovská, Kateřina ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
This master thesis deals with preparation of extracts from fruits of aronia, optimization of conditions for extraction and subsequent characteristics of the obtained optimal extract. In the theoretical part information about the botanical characteristics of Aronia melanocarpa and about its utilization are mentioned. Furthermore, the chemical composition of aronia fruits is described and the main biologically active substances contained in the plant are described. At the end of the theoretical part extraction and separation techniques, determination methods of antioxidant, antimicrobial activity and determination of aromatic active compounds are described. The experimental part describes the optimization of maceration so that the macerate contains as much polyphenolic substances as possible, as well as aromatic active substances. 40% ethanol, at a temperature of 60 ° C, with a weight solvent ratio of 1: 5, for 40 minutes proved to be optimal for the maceration of aronia fruits. The total polyphenol content of the optimal extract was determined to be 5237.2 ± 40.7 mgGAEkg-1 and the antioxidant activity by TEAC to be 512.5 ± 5.04 gml-1. 24 aromatic active compounds were identified in the extract, with the largest percentage being monoterpenes and aldehydes. Furthermore, it was found that the extract did not show antimicrobial activity against the microorganisms used (Bacillus cereus, Escherichia coli and Candida glabrata). The obtained results confirm that aronia extracts are an important source of many biologically active compounds and can be used in food as a natural source of nutritionally and sensory valuable substances.
Application of plant extract into non-chocolate sweets
Rychetský, Matěj ; Saláková, Alena (referee) ; Vítová, Eva (advisor)
This diploma thesis deals with the optimization of jelly candies production, application of herbal extract to produced candies, and subsequent characterization of produced samples in terms of volatile (aromatic) substances, total phenolic substances, antioxidant aktivity, and sensory quality. Optimization parameters – the amount of gelatin and the addition of citric acid, were selected based on the sensory analysis. Additions of 7,5 % gelatin and 2 % acid were proven to be optimal. The sources for the production of herbal extracts were the plants Aronia melanocarpa and Echinacea purpurea, which are known for their high content of bioactive substances. The further sensory analysis determined the optimal amount of extract added to jelly candies samples – in the case of chokeberry it was 4 % and in the case of echinacea it was 1 % of the extract. In the sample with chokeberry extract of optimal composition, ie 7,5 % gelatin, 2 % citric acid, and 4 % extract, 46 volatile substances were determined, of which nonanal (12,17 %) and thymol (8,70 %) were the most represented, the total polyphenol content was 472.88 ± 8.02 gGAEg-1 of the sample and the antioxidant activity was determined to be 828.99 ± 17.74 gTEACg-1 of the sample. The sample with echinacea extract of optimal composition, ie 7,5 % gelatin, 2 % citric acid and, 1 % extract, contained 56 volatile substances, the most represented being nonanal (12,08 %), thymol (6,19 %), and decanal (5,52 %). The total polyphenols in this sample were determined to be 291.09 ± 10.17 gGAEg-1 of the sample and its antioxidant activity was determined to be 850.91 ± 30.29 gTEACg-1 of the sample. Samples with the addition of chokeberry extract, which gave the confectionery a fruity, slightly sour taste and a pink to dark purple color, were considered more pleasant/acceptable; samples with echinacea had an herbal aroma and taste and orange color.
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.
Production and characterization of mead produced by different technologies
Kilian, David ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis is focused on the technology of producing mead from the chosen kind of honey with a variety of sugar concentrations with the use of modern producing technological procedures with the cold and hot process. The theoretical part is focused on the history of mead and its technological development. It focuses, in detail, on modern large scale technologies – both cold and also the hot process. In the practical part of the thesis, the production of samples of mead with various sugar concentrations from three kinds of honey with the use of two technological processes (hot and cold process) was conducted firstly. Secondly, the characteristics of the samples were conducted from the view of the volume of HMF – Hydroxymethylfurfural, ethanol, glucose, fructose, the chosen organic acids and elements with sensory analysis. The prepared samples were compared and discussed concerning differences to find out the differences of the use of the two manufacturing technologies (cold and hot process), the chosen kinds of honey and the influence of sugar before the fermentation on the final product.
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.
Production and characterization of cheese with the addition of plant extract
Kučerka, Štefan ; Zemanová, Jana (referee) ; Vítová, Eva (advisor)
This master´s thesis deals with production and characterization of fresh cheese with addition of herb extracts, specifically extracts from Plectranthus amboinicus and Echinacea purpurea. The purpose of this thesis was to prepare samples with higher sensory quality and nutritional value. Produced cheeses were characterized in terms of volatile (aroma) substances, fatty acid content, total phenolic substances, antioxidant activity and sensory quality. Cheese sample with added extract from E. purpurea reached the highest value of total phenolic compounds (0,172 ± 0,019 mgGAEg-1 of cheese) and antioxidant activity (91,2 ± 2,2 gTEACg-1 of cheese). Cheese sample with added extract from P. amboinicus, compared to standard cheese sample (without added extract) also reached higher values of total phenolic compounds and antioxidant activity. 43 volatile (aroma) compounds were identified in both samples with added extracts (P. amboinicus, E. purpurea), in standard cheese sample it was 33. In sample with E. purpurea camphor was present in high amount (15,23 %) responsible for the camphor aroma, camphor was also identified in small amount in sample with P. amboinicus. Highest volatile matter content was identified in sample with P. amboinicus. Standard cheese sample was rated as the best from the sensory perspective. Addition of extracts had negative effect on color, taste, and aroma perception of cheese. Strongest herbal taste was identified in sample with E. purpurea, brownish color of this sample manifested in lower pleasantness of color. Obtained results show, that extract addition increases the nutritional value of cheese (higher content of aromatic substances and phenolic compounds, higher antioxidant activity), but lowers sensory quality and overall consumer acceptability.
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.
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.
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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