National Repository of Grey Literature 229 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Characterization of minor fruit varieties in terms of use in the food industry
Jurečková, Zuzana ; Vítová, Eva (referee) ; Golian, Jozef (referee) ; Diviš, Pavel (advisor)
The thesis deals with one group of small fruits, the genus Ribes, ie currants, and gooseberries. It assesses their physical and chemical parameters with respect to the possibility of use in these properties for the design of a new type of product – beverages. Titration, spectrometric and other methods were used for the evaluation of these properties. A total of fifteen of these methods were available (total juice yield, juice pH, total dry matter, soluble fruit dry matter, titratable acidity, formolic number, reducing carbohydrate content, D-glucose, D-fructose and sucrose content, total polyphenolic substance content, anthocyanins, vitamin C and total antioxidant capacity) and a total of nine analytes (copper, iron, magnesium, phosphorus, zinc, manganese, potassium, calcium and sodium) were selected for the determination of mineral elements. For two years (harvest 2014 and 2015), these parameters were monitored for color variants of currants (white, red and black) and gooseberries (green-fruited, yellow-fruited and red-fruited). A total of six white varieties were tested in the group of currants - Olin, Jantar, Primus, Blanka, Viktoria and Orion, eleven varieties of red currants - Junnifer, Jesan, Detvan, Rovada, Rubigo, J.V.Tets, Tatran, Losan, Kozolupský raný, Stanca, NŠLS 11/6 and eleven varieties of black currant varieties - Ometa, Démon, Triton, Ben Hope, Ruben, Ben Gairm, Ben Lomond, Moravia, Ben Conan, Fokus and Ceres. A total of five varieties of green-fruited gooseberries were tested - Zebín, Mucurines, Rixanta, Rodnik and Prima. Yellow-fruited gooseberries were available in four varieties - Lemon Giant, Invicta, Golden Fig and Darek. The red-fruited gooseberries included varieties - Rolonda, Alan, Karat, Karmen, Krasnoslawjanskij, Himnomacki Rot, Remarka, Tamara and Black Neguš. Using Tukey's test, an analysis was performed and by scoring individual varieties based on the results of individual analyzes, a list of recommended varieties was compiled for further work on the development of a new beverage. Unfortunately, in 2015 there were very few fruits of green-fruited and yellow-fruited gooseberries, so it was decided that the volume of fruit will fall on the testing of bioactive substances. Therefore, at the end of the work, it is not possible to objectively evaluate these varieties of gooseberries in the whole range of analyzes. Therefore, the point evaluation of varieties was based on the averages of individual varieties. The red-fruited varieties were available in full, and therefore a full evaluation could take place. The most significant differences between red gooseberry varieties were in the content of bioactive substances (the content of polyphenolic substances, anthocyanin dyes, and vitamin C) and antioxidant capacity. These results were provided to the food subject, which continued to work with these values. Based on this project, utility model No. PUV 2016-33171 and the resulting combined drink based on wine and fruit juice were developed.
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.
Monitoring of chemical changes in ground coffee stored in different ways
Lajtman, Roman ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
This diploma thesis deals with the monitoring of chemical changes in ground coffee stored in various containers and then it deals with the determination of water, moisture and aromatic profile of coffee in individual containers, namely a can, a paper bag, a bag with a polyethylene liner, a bag from low density polyethylene with aluminium liner (LDPE + Al) and a glass container. At the beginning of the experiment it was found that the water content in the coffee was 4.72 ± 0.10 % and the moisture content was 9.47 ± 0.01 %. After the original sample was measured, the coffee was poured into 5 packages. At the end of the experiment, a can was chosen as the most suitable package where the lowest water content was measured. The water content was determined to be 6.51 ± 0.11 % and the moisture content was 9.93 ± 0.01 %. However, the differences between the other packages, apart from the paper bag, were very small, and thus in general it can be said that the can, the LDPE + Al package, the bag with the PE liner and the glass container are suitable for storing ground coffee. A total of 44 aromatics were identified when determining the aromatic profile in coffee by HS-SPME-GC-MS. The most represented groups of substances were furans and pyrazines. During storage, there was some loss of substances due to 2 mechanisms. The first of them is evaporation and the second one is the oxidation reactions themselves. Most aromatic substances have evaporated / degraded in paper packaging, where this large decrease is related to its barrier properties. A glass container was chosen as the most suitable packaging with the least loss of aromatic substances.
Confirmation of identification of volatile substances by calculation of retention indexes
Cviková, Sára ; Šimíčková, Adéla (referee) ; Vítová, Eva (advisor)
This bachelor thesis is focused on verifying the identification of volatile compounds using retention indices. The HS-SPME-GC-MS was used for determination. First part is theoretical and is focused especially on the brief definition of terms such as gas chromatography, retention time, retention index, mass spectrometry, however, the chemical and physical description of the CBD oil sample, which was used to prove the function of retention indices, is also mentioned. The standard homologous set of n-alkanes (C8 - C20) was used to determinate the retention indices, which was analyzed under the same conditions as the sample of CBD oil. In the CBD oil 38 volatile compounds were successfully identified. Their identification was confirmed by calculating their retention indices using the equation by H. van der Dool and D.J. Kratz, and comparing with tabulated values for the same type of chromatographic column.
Determination of acrylamide in coffee by high performance liquid chromatography
Vajdíková, Tereza ; Vítová, Eva (referee) ; Diviš, Pavel (advisor)
The bachelor's thesis aimed to optimize the method of determining acrylamide in coffee using high-efficiency liquid chromatography with a diode-array detector. In the theoretical part of the bachelor's thesis, attention was paid to the taxonomic distribution of coffee, it's processing and chemical composition. Part of the theoretical frequency of the work involved describing the formation of acrylamide in coffee and possible methods of determining it. The practical part looked at validating the method, which was used in the analysis of coffee samples. The individual samples of coffee varied in the type of coffee and the societies where the coffee was obtained. Determination of the acrylamide content has been carried out on commercial, franchised, and selective coffees of the arabica species. Finally, the determination of acrylamide was made in the coffee of various types, in robusta and arabica.
Influence of increased carbon dioxide concentration on grain protein composition in early and late wheat variety
Smrčková, Kamila ; Vítová, Eva (referee) ; Hrstka, Miroslav (advisor)
This bachelor thesis deals with the effect of increased CO2 concentration (700 ppm) on the content and composition of wheat grain proteins in early (Avenue) and late (Tobak) wheat varieties. Three methods were used to determine the proteins in wheat grain: the Kjeldahl determination of crude protein content, the determination of wet gluten, and finally the gravimetric determination of gliadins and glutenins after extraction. A different response of the varieties to the increased CO2 concentration was found. The early Avenue variety was much more sensitive to the effects of increased CO2 concentrations. The gliadin content decreased, while the glutenin content increased with increasing CO2 concentration. The total gluten protein content increased in elevated CO2 concentration, independently of nitrogen fertilization. Its content correlates in our work with the content of wet gluten.
Characterization and optimization of sensory quality of jelly sweets
Knotek, Vojtěch ; Vespalcová, Milena (referee) ; Vítová, Eva (advisor)
This bachelor thesis focuses on monitoring and optimization of moisture of starch during jelly sweets processing. The theoretical part focuses on technology of manufacturing jelly sweets and description of raw materials needed for production. The methods for measurement of starch moisture are briefly described. The experimental part focuses on stabilization of moisture of starch during jelly sweet processing, specifically when pouring gelatinous mass into starch forms. The drying scale method was used to measure starch moisture. Recommended starch moisture is up to 8 %. During the two-month measurement, this value was always 0.5 % higher. On the basis of the results of this work, slight modification in the starch drying was made. This led to a reduction in starch moisture but not yet optimal.
Application of herbal extract into suitable food product
Chmelařová, Adéla ; Saláková, Alena (referee) ; Vítová, Eva (advisor)
This master’s theses deals with a production and characterization of hard candies, a type of non-chocolate sweets. Methods of candies production were optimised with focus mainly on boiling temerature which significantly affects product consistency and stability. Production process optimisation was based on methods of sensoric analysis and Karl-Fishcher titration used to determine the water content in the product. Plant extracts Plectranthus amboinicus and Aronia melanocarpa which were applied to hard candies are rich source of bioactive compounds upon which prepared candies were characterised. Optimal conditions for candies production were – boiling temperature 155 °C, volume of citric acid 0,4 %, volume of Plectranthus extract 2 % and volume of Aronia extract 3 %. There were 42 volatile compounds identified in a sample containing 2 % of Plectranthus extract. Based on their content , the most significant compounds were carvacrol (8,44 %), carotol (1,47 %) and levomenthol (0,99 %). Total content of polyfenols was measured to be 7,10 ± 0,55 mgg-1 per 1 g of hard candy sample, antioxidant activity of a sample was 66,19 ± 1,80 gml-1. It was identified that 42 of volatile compounds were present inside the sample with 3 % of Aronia extract. The most significant being carotol (30,67 %), menthol (1,52 %) and thymol (1,39 %). The overall presence of polyphenols was measured to be 13,87 ± 1,12 mgg-1 per 1 g of the candy sample, the antioxidant activity of the sample was 115,00 ± 2,86 gml-1.
Study of extraction of biologically active substances into fatty base
Komárek, Šimon ; Vítová, Eva (referee) ; Zemanová, Jana (advisor)
This diploma thesis deals with macerates of comfrey (Symphytum officinale) in selected fats (food lard, cosmetic lard and almond oil). Selected fats were first characterized by dry matter content, saponification, acid, iodine number, peroxide value. At the same time, total and free fatty acids were determined using GC-FID. Macerates were prepared by extraction of comfrey roots with selected fats. In prepared macerates the change in acid and peroxide value was monitored, as well as the content of selected bioactive compounds. The content of total phytosterol and total carotenoid content was determined by UV-VIS spectrometry, phytosterols and carotenoids were also analysed using HPLC-DAD. Total phenolic content was measured using Folin-Ciocalteu reagent and antioxidant activity by ABTS assay. The measured properties were then compared with industrially produced comfrey ointment. In macerated fats the increase in acid and peroxide value was determined. Furthermore, an increase in the content of total phytosterols and total carotenoids was observed. Using HPLC-DAD the content of -sitosterol and stigmasterol was determined, but carotenoids were not detected. Of the tocopherols, only DL--tocopherol acetate was detected. During maceration, the content of total phenolic compound in fat increased, which caused a change in antioxidant activity.
Influence of capsaicin derivatives on pungency of chili peppers
Paulišová, Sabina ; Pořízka, Jaromír (referee) ; Vítová, Eva (advisor)
This diploma thesis is focused on the influence of the three most represented capsaicinoids – capsaicin, dihydrocapsaicin and nordihydrocapsaicin – on the sensory properties of five varieties of chili peppers. Aji Lemon Drop, Serrano, Jamaican Yellow, Habanero Chocolate and Bhut Jolokia were selected for this thesis. Determination of capsaicinoids content was performed using HPLC-DAD. The content of capsaicin in dried fruits ranged from 359 to 320 gg-1, the content of dihydrocapsaicin in the range of 130–7 767 gg-1 and the content of nordihydrocapsaicin in the range of 7–456 gg-1. The pungency of the samples was 8 928–601 338 SHU. The sensory evaluation of selected varieties of chili peppers was attended by 20 evaluators representing ordinary consumers. The subject of the evaluation was mainly the intensity of burning and sharpness, its pleasantness and identification of the place of manifestation of thermal sensations. Furthermore, the onset of burning and sharpness from the insertion of peppers into the mouth, the duration of thermal sensations, the intensity of sweetness and juiciness, the presence of other flavors and the texture of the fruit. Statistically significant differences were observed between the evaluation results. The low intensity of burning and sharpness of the Jamaican Yellow variety was assessed as neutral to rather pleasant, while the high intensity of thermal sensations of the Habanero Chocolate and Bhut Jolokia varieties was perceived as unpleasant. The Aji Lemon Drop and Serrano varieties were judged very similar from a sensory point of view. By combining the results of capsaicinoids content measurement and sensory analysis, significant correlation relationships were found between the evaluated parameters. With a higher content of capsaicinoids in peppers, their pungency (expressed in SHU) increased, at the same time a higher intensity of thermal sensations and their longer duration were found during consumption. On the contrary, with a high intensity of burning and sharpness, the pleasantness of these perceptions decreased. The onset of these feelings did not affect the observed properties. The higher the intensity of juiciness, the higher the sweetness of the fruit; however, these properties were not significant in terms of the content of combustibles or the intensity of thermal sensations. The effect of individual capsaicinoids on the site of thermal sensation has not been statistically proven.

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