National Repository of Grey Literature 89 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
Analysis of polyphenolic compounds in selected brewery matrices by HPLC-HRMS method
Zušťáková, Veronika ; Sobotníková, Jana (advisor) ; Mikyška, Alexandr (referee)
The thesis has focused on the separation of proanthocyanidins (Pas) in beer, raw beer material and beer intermediates (wort, hopped wort, green beer) by using high performance liquid chromatography coupled to high resolution mass spectrometric detection. A chromatographic column XSELECT HSS T3 was used for separation of individual proanthocyanidins. Mobile phase was formed by a mixture of 0,1% formic acid in water (A) and 0,1% formic acid in acetonitril (B), separation was conducted in gradient mode. Calibration range for catechin and procyanidin B1 a B2 was linear in the range from 10 µg.l-1 to 200 µg.l-1 and for epicatechin from 5 µg.l-1 to 200 µg.l-1 . Limit of quantitation (LOQ) was set to the lowest point of calibration curve, hence for catechin, procyanidin B1 and B2 was LOQ = 10 µg.l-1 and for epicatechin was LOQ = µg.l-1 . Yield of method of the observed Pas was very good, where yield oscillated around 100%. The method also had excellent repeatability, where the relative standard deviation (RSD) was lower then 20%. After optimization of this method it was used for observation of profile changes during brewery process in catechin, epicatechin, procyanidin B1, B2 and B3. It was discovered, that catechin, epicatechin, procyanidin B1 and B2 originate mainly from hops and procyaniding B3 is...
Pharmacologically active compounds in hops
Pýchová, Kateřina ; Cvrčková, Fatima (advisor) ; Mašková, Petra (referee)
The hop plant (Humulus lupulus) is used not only in brewing but also in phytopharmacology and phytotherapy. Among the isolated or chemically produced substances used for healing are xanthohumol, 8-prenylnaringenine and α and β-bitter acids. Nowadays, a lot of attention is paid to their effect on humans - especially to their anticancer activity. But there is a lack of information about the importance of these substances for the hop plant itself. Most of the plant secondary metabolites originally serve for protection of the plant against pathogens and herbivores. The selected metabolites are not an exception. The purpose of this work was to summarize the published data about the biological importance of selected hop secondary metabolites and the effects they have on other organisms than plants, with an emphasis on humans.
Beer bioflavouring by dry hopping using czech cultivars of hops
Gajdušek, Martin ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with the influence of dry hopping on selected analytical and sensory properties of beer. The effect of dry hopping was observed using Czech hop varieties Kazbek and Uran, which were added to the wort during the main fermentation phase in doses of 3 and 6 gdm-3. The contact time of hops with wort was 3, 6 and 9 days. The experimental part describes the technology of preparation of the reference beer, in which dry hopping were subsequently performed. A parallel measurement was performed on each sample. In terms of the basic parameters of beer, the effect of dry hopping, especially its length, on the ethanol content was observed. With a longer period of dry hopping, the concentration of ethanol in beer increased. The higher alcohol concentration was also associated with a decrease in the apparent extract. In terms of color and pH of beer, the effect of dry hopping has not been proven. Elemental analysis performed by optical emission spectrometry with inductively coupled plasma revealed an increase in the concentration of calcium, magnesium, and iron due to dry hopping. No statistically significant difference was observed for manganese and barium compared to the reference. In terms of bitterness, a significant increase was identified in dry hopped beers compared to the reference, the value being dependent on the dose of hops used. The effect of the hop variety has not been proved. Concentrations of organic acids determined by ion-exchange chromatography with a conductivity detector were affected by dry hopping only in the case of lactic acid and acetic acid. An increase in lactic acid was observed compared to the reference, also related to the degree of fermentation. While in the acetic acid content the hop samples showed a lower concentration than the reference sample. The concentrations of myrcene, humulene and geraniol were determined by gas chromatography with a mass detector. These are volatile components of hop essential oils. Dry hopped samples recorded significantly higher concentrations of all aromatic substances compared to the reference. In terms of hop time, the highest concentrations were shown by samples hopped for three days. The results of the sensory analysis show that the overall best rated sample is a sample hopped with the Kazbek variety with a dose of 3 gdm-3 for three days. Beer which was dry hopped for the shortest time also showed the lowest intensity of bitterness, which was perceived positively.
Study of sensory-active compounds of hops in dry-hopped beers
Zlochová, Tereza ; Sobotníková, Jana (advisor) ; Jelínek, Ivan (referee)
Study of sensory-active compounds of hops in dry-hopped beers Key words: hop, hop oils, dry-hopping, beer, beer-aging, beer sensory analysis Nowadays, dry-hopping is a widely used method of beer making, with its pros and cons. The main purpose of dry-hopping is to derive specific hop aroma to beer in its very unchanged form. The essential part of this work consists of a study of hop essential oils, as the main providers of desired hop aroma. Firstly, the validation of methods for isolating essential oils from hop material and beer is carried out. Secondly, the transfer of these volatiles in process of dry-hopping is studied and the impact on beer aroma profile is discussed. Subsequently, changes of essential oils profile during beer-aging are observed and evaluated with a valuable tool, the sensory analysis. This study was realized on beer samples from Brewers' Choice program, thanks to the Research Institute of Brewing and Malting and Lenka Strakova, the Pilsner Urquell brewer.
Chmelové produkty a možnosti jejich použití při výrobě piva a dalších nápojů
Tichá, Kateřina
The bachelor thesis deals with the theme of hop products which are available on domes-tic market. The first part of the work is focused on the chemical composition of hops, where the most important part is isomerization of bitter acids. There are also mentioned hop varieties, cultivation and processing technology after harvest. The second part describes the technology of domestic production of hop products and their use in the brewing industry. There is also a comparison to technology abroad. In conclusion the work focuses on the utilization of hop products generally in the beverage industry.
Technologické možnosti chmelení piva
Polanský, Petr
This diploma thesis discusses about technology of beer hopping. The first part describes beer history, beer brewing, hops and hop products. The second part deals with the practical beer brewing using different hop technologies. Seven different beers were brewed using the same dose of the same hops and one using the hop extract. IBU values were determined by calculation and spectrophotometer. A sensory analysis of the resulting beers was also carried out. It has been proven that different beer hopping technologies have shown a positive change in the resulting bitterness of beer. The best taste was the beer brewed with shortened hoping.
Možnosti chmelení piva chmelovými extrakty a výrobky z chmele
Tichá, Kateřina
The aim of this thesis is to summarize the options of hop products leaded by hop extracts. The literature research focuses on chemical composition of hop, key transformation of hop bitter acids used in the brewing industry and also describes the technology of production of individual hop preparations and possibility of their application. The next part summarizes the beer production process including associated mikrobiology, which is an importand part of all stages of beer production. The experimental part describes production of six variations of beer chosen from different hop products, their chemical analysis and sensory evaluation. The results of the tests are evaluated statistically and are compared with each other at the end of the thesis.
Možnosti výroby cukrovinek s využitím vybraných surovin
Vlčková, Petra
This bachelor thesis is focusing on various types of production of hard candies by usage of special raw materials. In the first part the thesis focuses on the general production technology of hard candies where the most important area of attention are given to sugar syrup productions, starch syrup and its various degrees of concentration. In the second part the thesis focuses on the production technology of the special raw materials and their extracts. Firstly, it focuses on the beer production technology, especially the wort, as a possible special raw material. Furthermore, the technology of wine production and, in particular, wine mash, which might be a special raw material for the production of sweets.
Vliv stáří chmelnice na druhové složení plevelů
Suchánková, Marie
Bachelor thesis occupies with weed evaluation in selected hop plants. The literary part is focused on hop production in the Czech Republic, botanical and biological characteristics of hops. Both perennial, both in the elderly and in the younger, fytocenological relevé were prepared. The evaluation was conducted in three deadlines in April, June and August 2017. The values obtained were statistically evaluated by DCA and CCA analyzes.The observation took place at the agricultural cooperative in Kokora. Two weeds have been recorded as 26 weeds. In the older hopper there were Solanum nigrum, Tripleurospermum inodorum, Galinsoga parviflora, Elytrigia repens, Atriplex patula, Rumex obtusifolius, Lmium amplexicaule, Holosteum umbellatum. In the younger hopper there was mainly Persicaria lapathifolia.
Biologicky aktivní látky v pivu
Slováček, Jan
Bachelor thesis „Biologically active substances in beer“ is focused on the active substances contained in beers and the influence of these substances in the human body. The first part of the thesis outlines the history of brewing in the world and in our country. In addition, raw materials needed to produce beer and the brewing proces itself are described. The last part of the thesis is focused on biologically active substances found in beer. The effect of these substances on the human organism is also described. Finally, some of the methods by which the active substances in beer are determined.

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