|
|
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.
|
|
|
Monitoring of mercury and methylmercury content in fish meat and evaluation of risks associated with the consumption of this meat
Křížová, Lucie ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
Mercury and its compounds are one of the most toxic global pollutants in the environment. It occurs in all segments of the environment, and it attains the food chain ang human body by people consuming fish. The theoretical part of this thesis examines the characteristics of mercury, its occurrence, the roots of its pollution, and the toxicity of various forms of mercury. Consequently, the thesis delineates analytical methodologies applied to determine the overall level of mercury and chemical forms of mercury. The practical part focuses on monitoring the level of mercury and methylmercury in 12 extracts of fish meat. The analyzer AMA 254 has been used to determine the level of mercury and methylmercury in these extracts. Based on the level that resulted from the measurements, the thesis concludes a risk that correlates with consuming this type of meat.
|
|
|
Detoxification of coffee sediments by oxidation processes
Maňáková, Helena ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with the detoxification of used coffee grounds by the oxidation processes. The theoretical section describes the characterization of coffee beans and used coffee grounds. Furthermore, this section describes the valorisation of coffee grounds, especially its application as a fertilizer. The final part of the theoretical section focuses on the characterization of phenolic compounds, which are responsible for toxic properties of used coffee grounds, and analytical methods are described, which include UV–VIS spectrophotometry and high–performance liquid chromatography. The aim of the experimental part is the sample preparation, the application of the effective detoxification process and the analysis of the detoxificated used coffee grounds, focusing on the content of phenolic compounds. At the end of the experimental part, data processing is described. Three types of coffee grounds were used for determination of phenolic compounds: raw, defatted and the third type was defatted and simultaneously hydrolysed. High amounts of phenolic acids were identified in every sample, especially the gallic, ferulic, chlorogenic and caffeic acid. After an oxidizing agent was applied, positive detoxification of every sample of used coffee grounds was confirmed. For the most effective and most economical oxidation, a 1% oxidizing agent was chosen, which after a 10–minute oxidization efficiently reduced the content of the phenolic compound.
|
|
|
Preparation and characterization of protein concentrates from wheat bran
Hubačová, Klára ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
The diploma thesis deals with usage of wheat bran as a source of high-quality proteins. Every year mill industry produces large amounts of by-products. These by-products are constituted by wheat bran. There is a big effort to use these type of materials within a circular economy. Wheat bran contains about 14–18 % proteins which appears to be a good component for valorisation. It is possible to extract proteins from bran according to their behaviour in the range of pH. Proteins are soluble in alkaline pH and can be precipitated around their isoelectric point. The final treatment of precipitated proteins is lyophilisation. The next step is characterisation of the product. There are a few parameters to analyse: purity of the isolate, amino acid profile, composition of minerals, water contain etc. Interest in nutrition is on the rise not only by professional sportsman. This isolated product could serve as a potential protein supplement.
|
|
|
Developement and optimalization of methods for extraction of selected compounds from Hypericum perforatum
Chytil, Dalibor ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
Bachelor's thesis deals with the optimization of processes for extraction of phenolic compounds from St. John´s Wort (Hypericum perforatum). The theoretical part of the work focuses on characterization of this herb, its botanical classification, traditional use, chemical composition and curative effects. Increased attention is further devoted to a theory of preparation of samples for extraction of phenolic compounds and suitable techniques for extraction and characterization of phenolic compounds from extracts of St. John´s Wort. The experimental part of the thesis deals with application of theoretical knowledge. When optimizing the emphasis was on influence of solvent (water acified to pH 4, pH 5, pH 6), influence of extraction technique (ultrasound extraction, subcritical water extraction, maceration) and influence of extraction period (10, 20, 30 min). Extracts were subjected to determination of selected parameters (total phenolic content, total flavonoid content, antioxidant activity) in leaves of St John´s Wort harvested in June 2016 using UV-VIS spectroscopy. The used extraction techniques are significantly different from each other.
|
|
|
Quantification of food waste in municipal waste and the possibility of processing this waste
Orságová, Marie ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
The theoretical study of anaerobic digestion is designed to predict the amount of biogas in food waste. The theoretical part characterizes the processing of biodegradable waste as well as the use of biogas and the calculation method for determining biogas production. In the experimental part, the analytical technique of inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine minerals (K, Ca, P, Mg, Na, Zn, Cu, Fe and Mn) in food waste, as well as elemental analysis for carbon, oxygen, hydrogen and nitrogen determination. This thesis provides a simplified model that predicts the amount of produced biogas and could be used for further feasibility studies, such as bioreactors dimensioning. The method can be used for different starting materials and repeated for other similar applications in an effort to extend anaerobic digestion systems as a source of clean energy.
|
|
|
Optimization of HPLC-ELSD method for determination of sugars in foods
Laba, Marija ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This master's thesis deals with the optimalization of HPLC-ELSD method for the determination of carbohydrates in food. The theoretical part focuses on the classification and characterization of carbohydrates, the occurrence of carbohydrates in food and their physiological importance. There was targeted mainly glucose, fructose, sucrose and maltose. There is a brief summary of the analytical methods that can be used to determine carbohydrates. Experimental part is based on a literary review. It also deals with high performance liquid chromatography with evaporative light scattering detector. The main content in this part is the optimalization of condition for reliable and rapid separation of the most frequently occurring carbohydrates in foods. The carbohydrates were identified and quantified under optimum condition in real samples specifically in fruit juice, beer, ketchup and red pepper powder. The result is commented in conclusion.
|
|
|
Characterization of new czech hop varieties
Faruzel, Vojtěch ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
In this thesis the problem of characterization of new Czech hop varieties was investigated. The selected new varieties were Mimosa, Jazz and Blues. Their composition was compared with the widely used varieties Žatecký poloraný červeňák and Kazbek. The content of -bitter acids and -bitter acids, total phenolic content, flavonoid content and antioxidant activity were determined by UV-VIS spectroscopy for all hop varieties. The composition of hop essential oils was estimated by SPME-GC-MS. The diversity of the hop varieties was confirmed from the measured data by statistical analysis. The new varieties showed statistically significant differences in all monitored parameters, especially in comparison with the varieties Žatecký poloraný červeňák and Kazbek. The quantitatively different representation of -bitter acids and -bitter acids has an influence on the character and intensity of bitterness of these hop varieties. The composition of the hop essential oils, the content of phenolic substances, flavonoids and antioxidant activity are reflected in the different organoleptic properties of the hops analysed and of the beer.
|
|
|
Extraction of anthocyanin pigments from elderberries pomace
Lošková, Tereza ; Pořízka, Jaromír (referee) ; Vespalcová, Milena (advisor)
This Diploma thesis deals with the production of the concentrate from the Elderberry marc extract (Sambucus nigra L.). The basic chemical characteristics in this concentrate were determined. The theoretical part of the thesis deal with the botanic characteristic of the Elderberry and its berries. The characteristic of the phenolic compounds, mainly anhocyanins was summarized. The use of the anthocyanin pigments in the food industry, the possibilities of their extraction and the concentrate production was discussed. Thereafter the methods of the anthocyanin content and the phenolic content determination were described. In the experimental part of study, the production of the anthocyanin rich extract from Elderberry marc was optimized. The extraction of the marc by the 1:1 ethanol/water (V/V) solvent with the ratio marc/solvent 1:2 (w/V) showed the most convenient. The production of the concentrate followed. During the concentration on the rotary evaporator the pigment degradation was investigated. The degradation decreased with the decrease of the temperature. The final concentrate was prepared from the extract on the rotary evaporator by 45 °C for 15 minutes. This product had the 7times lower volume compared to the initial extract. In the final concentrate come of the chemical characteristic were determined. By liquid chromatography (HPLC) the major pigments cyanidin-3-sambubiosid and cyanidin-3-glucosid were determined. Their total content was determined to 34,9 gl-1. The total anthocyanin content was determined by pH differential method to 7,1 gl-1 (expressed as cyanidin-3-glucoside equivalent). The total phenolic content was determined to 27,1 gl-1 (expressed as gallic acid equivalent) by Folin-Ciocalteu method. By electron paramagnetic resonance the increase in antioxidant activity with the increase in concentration was found. Up to 42 aromatic compounds was determined in Elderberry marc, its extract and the final concentrate.
|
|
|
Influence of the filtration and pasterurization on content of selected vitamins in beer
Šimíčková, Adéla ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
This master thesis focuses on the influence of the filtration and the pasteurization on the content of the selected vitamins in beer. Specifically, the vitamin B2, B3, B6, B9 and B12. The high performance liquid chromatography with diode array detector was used as a separation method for the vitamin content analysis. First this method was optimized and then validated. The data obtained by analyzing 28 beer samples were evaluated using a statistical method – the analysis of variance. This method provided parameters P, F and Fcrit which are important for the assessment of the statistically significant differences between the individual groups of beer . Based on these parameters, a significant effect of the filtration was observed for the vitamin B2 and B3. The filtration has reduced the amount of the vitamin B2 while it increased the concentration of the vitamin B3. The pasteurization had no significant effect on the vitamin content.
|
guest ::
