National Repository of Grey Literature 13 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Study of the authenticity of spices and condiments
Štursa, Václav ; Golian, Jozef (referee) ; Urík, Martin (referee) ; Diviš, Pavel (advisor)
This disertation deals with geographical authentification of different types of spices and spice preparations. Investigated spice species were garlic (Allium sativum), ground pepper (Capsicum anuum), and dried carrot (Daucus carota). Theoretical part of the disertation describes main qualitative parameters of the examined species and production technology, means of food adulteration and statistic methods used in chemometrics. The aim of this dissertation was to verify the hypothesis whether it is possible to use targeted analytical techniques commonly used in quality control of spices and condiments, and statistical processing of measured data to distinguish samples of spices and condiments of different geographical origin. The use of non-targeted analysis was also investigated. Samples of garlic and ground pepper were used for targeted analysis. The examined parameters were dry matter and moisture of the sample, ash content, total phenolic content according to Folin-Ciocaulteu, carbohydrate content, alliin concentration, total nitrogen content, total color pigment (ASTA), pH of aqueous extract, total fat content, and concentration of selected elements (Ca, Cu, Fe, K, Mn, Mg, Na, P, Zn). The instrumental techniques used were molecular absorption spectrometry, inductively coupled plasma optical emission spectrometry and high performance liquid chromatography. The obtained data were statistically processed by analysis of variance (ANOVA) and principal component analysis (PCA). Using statistical analysis significant differences between samples that came from more distant areas were found. However, samples from closer areas could not be distinguished. The researched hypothesis could not be unequivocally confirmed or refuted. Metabolic fingerprint of carrot samples was determined using non-targeted analysis. Metabolic analysis was performed using the tandem LC-TOF-MS technique. The data were processed by recursive peak extraction (BRE) and subsequently uvaluated with PCA. The samples were divided into clusters according to their origin. Targeted and non-targeted techniques have great potential in verifying the geographical authenticity of different types of spices. However, the main condition is consistent and sufficient sampling, guaranteed information on the origin of the sample and obtaining a sufficient amount of input data for statistical analysis.
Monitoring the stability of the beer brewing process
Tichá, Anna ; Štursa, Václav (referee) ; Diviš, Pavel (advisor)
The bachelor thesis deals with the analysis of 3 samples of the same beer, brewed in different batches of the brewing process. The analyzed sample is Dalešická jedenáctka - light lager of 11% of the Stock Brewery Dalešice, a.s., which was taken directly from the lager tanks in the brewery. The aspect we have examined were total protein content, total carbohydrate content, maltose content, total polyphenol content and ethanol content. The Hartree-lowry method was used to analyzed the total protein content. Total carbohydrates were measured spectrophotometrically using anthrone reagent. The maltose content was analysed by HPLC with an ELSD detector. The total polyphenol content was analyzed by the Folin-Ciocaltau reagent method and measured spectrophotometrically. The ethanol content was analyzed on a HPLC using a refractometric detector. The aim of the work was to compare to what extent the process of beer production is stable and what parameters may change in the final product
Influence of beer protein on foam stability
Benda, David ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the influence of beer proteins, phenolic compounds, bitterness and selected metal ions on beer foam stability. The theoretical part describes beer foam from the physical aspect, beer foam stability and its measurement and the factors that positively or negatively influences the stability and quality of the beer foam. In the theoretical part are described selected proteins that influence beer foam. In theoretical part is described the origin and technological significance of proteins. The experimental part is dedicated to the measurement of beer foam stability with the NIBEM method, the analysis of total protein content, the analysis of total phenolic content, bitternes and element analysis of beer samples. Measured data indicated correlations between protein content, phenolic compounds content, bitterness and metal ions with the beer foam stability. The results show that proteins and phenolic compounds as isolated parameters don’t essentialy affect the beer foam stability. It was found out, that bitterness as isolated parameter influences the beer foam stability the most.
Determination of nitrate in root vegetables
Fiala, Petr ; Štursa, Václav (referee) ; Diviš, Pavel (advisor)
The Bachelor thesis deals with the study of nitrates occuring in different species of root vegetables. The aim is to compare the amount of nitrates in common type of vegetables to bio vegetables. The theoretical part of the Bachelor thesis is devoted to root vegetable in general and also to nitrates and their influence to human health and nature. Fertilizers and organic agriculture are also mentioned. The last chapter focuses on the analytical method. The measurrement is carried out by the ion chromatography and the outcome of nitrate concentrations in both types of vegetables is compared and discussed. The results point out higher concentration of nitrates in bio-quality vegetables.
Characterization of different bran species in terms of ferulic acid content
Nábělek, Jakub ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This bachelor’s thesis works with an alkaline extraction of a ferulic acid from different kinds of cereal bran. Another researched issue was extraction of nutritionally interesting elements extracted from bran and from hydrolysed waste. Those extracts has possible usage as a mineral fertilizer for plants. In the theoretical part, this thesis deals with problematice of cereals, composition and differences in a cereal grain depending on kinds of cereal and an enviromental conditions. Chemical composition of cereal materials, focused on phenolic acids are also described. Another part deals with theoretical background of methods for the extraction of phenolic acids from bran with description of advantages and disadvantages. Methods for alkaline hydrolysis and extraction of minerals from different kind of bran bran are described in experimental part of this work. Sodium hydroxide (0,5 M) was used for the hydrolysis of bran material. For the determination of the yields of ferulic acid, HPLC method with UV/VIS detection at wave-length 330 nm with usage of mobile phase mixture of methanol and 0,5 % solution of formic acid was used. Acidified deionized water was used for the extraction of nutritionally interesting elements from bran and also from the hydrolyzed material. For the determination of the elemental composition of extracts (Cu, Fe, Zn, Mn, P, Ca, K, Mg), ICP-OES method was used. It was found, that differences in wheat bran species in terms of yields of Ferulic acid are satistically important. The biggest yields of ferulic acid was obtained from the sample of spelt. The smallest yields of this acic was obtained from the sample of oat. Content of micro and macro-elements showed statistical important differences in different kinds of bran and their hydrolyzed waste. Most abundand elemets were obtained from rice bran and from spelts hydrolyzate. The smallest abundand elemens were obtaned from oat bran and hydrolyzate.
Determination of basic nutritional parameters in edible insects
Korček, Jakub ; Štursa, Václav (referee) ; Diviš, Pavel (advisor)
In this bachelor thesis is dicussed nutritional value of chosen insect species. Analysed samples consisted of worms, crickets and locusts. Analysed parameters were: total nitrogen, crude protein, total lipids and content of chosen elements. Total lipids were, after homogenization, determined by Soxhlet method, using diethyl ether as a solvent. Prior to protein and element determination, samples did undergo Kjehldal digestion process, using sulfuric acid. Weiniger catalyst was only added to samples digested for protein measurement. Element content was determined by optical emission spectrometry with inductively coupled plasma (ICP-OES). Crude protein was determined by Kjeldahl method. The highest protein content was determined in crickets. (75 ± 5) %. Locusts contained the highest lipid content (33 ± 2) %. We also found out, that samples were rich in calcium, potassium, manganese and zinc, which are all important elements for the proper functioning of our body. The results of this thesis prove, that insects can present nutritionally important food.
Developement and optimization of the method for the extraction of ferulic acid from wheat bran
Hubačová, Klára ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
Bachelor thesis is considering usage of wheat bran for an extraction of ferulic acid. Wheat bran is a large-scale by-product of milling industry which is produced during milling of cereals (wheat) into flour. This low-cost product is usually used as a livestock feed. An initiative is raised for some other potential applications, because too large quantity produced every year can not be consumed just as a feed. There is a significant amount of phenolic acids from which ferulic acid is the most abundant one. It was found out after examination of structure of the wheat bran. This acid is connected with polysaccharides of a cell wall. The alkaline hydrolysis was used to disrupt a linkage between ferulic acid and polysaccharides. Then ethanol was added to precipitate the polysaccharides and the mixture was filtered. The filtrate contains ferulic acid which has great health benefits such as anti-inflammatory, antioxidant, anti-carcinogenic, antimicrobial effect etc. It plays an important role as an agent against UV radiation in the cosmetic products.
Analytical methods for verifying the authenticity of the wine
Flegr, Šimon ; Štursa, Václav (referee) ; Diviš, Pavel (advisor)
This bachelor’s thesis deals with the authenticity of wine, focusing on the authenticity of geographic origin. The theoretical part of this work summarises the main components of wine and their changes during the production proces. Control techniques are introduced, including the ones used by the goverment’s control bureau (SZPI) and other documented methods. Areas recognised for growing wine are described, including the Morava area in Czechia and its imminent adjacent areas in Austria and Slovakia. Experimental part deals with the trace amount analysis of selected elements and phenolic compounds. The element analysis was conducted using mass spectrometry and optical emission spectrometry, whilst the phenolic compounds were separated using high-pressure liquid chromatography with spectrophotometric detection. The results were analysed using discrimination analysis to separate groups with different areas of origin, with the aid of data from former research.
Extraction of bioactive substances from black currant pomace
Sedláčková, Lucie ; Štursa, Václav (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals with extraction of bioactive substances from black currant pomace (Ribes nigrum). The theoretical part contains the botanical characteristics of the plant species Ribes nigrum. It is also devoted to the biologically active substances contained in black currant and possibilities of using black currant in the food industry. The fourth chapter deals with description of phenolic compounds, their distribution and methods of determination of phenolic substances. The fifth chapter describes selected extraction procedures. In the experimental part, there were extracted dry black currant pomace in order to optimize the extraction process and obtain the highest yields of dyes. In addition, were determined the selected chemical and physical characteristics of blackcurrant juice and extracts from blackcurrant pomace. A better solvent was a mixture of water and ethanol in a volume ratio of 1:1. After 14 hours maceration of dry pomace, were obtained 769,9 mg anthocyanins per 100 g of dry material.
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.

National Repository of Grey Literature : 13 records found   1 - 10next  jump to record:
Interested in being notified about new results for this query?
Subscribe to the RSS feed.