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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.
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Determination of selected parameters in special types of beers brewed in the Czech Republic
Fähnrichová, Nikola ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with analysis of special types of beer brewed in the Czech Republic using three instrumental methods. Polyphenols were determined by high performance liquid chromatography. To determine organic acids was used ion exchange chromatography. Elementary analysis was performed by inductively coupled plasma optical emission spectrometry. The theoretical part of the work describes technology of beer production, chemical composition of beer, especially groups of substances which were analysed in this thesis. Principle of used methods is also described. The practical part of the work deals with preparation of tested samples, calibration samples and process analysis. The obtained results of analysed substances are summarized in the tables, discussed and compared with results of analysis of other authors. For the analysis it was used eighteen different types of special beer produced in the Czech Republic.
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Home brewery
Hlubinka, Jakub ; Tuhovčák, Ján (referee) ; Hejčík, Jiří (advisor)
The Bachelor’s thesis deals with phenomenon of home-brewing. The first part focus on technology of brewing with understanding is entry requirement for correct draft of home brewery. Second part describes possibilities of specific solution and configuration of each component of equipment for beer production in home environment. At the end is project of home brewery suitable for training of measurement and regulation in Master's degree program „Environmental Engineering.“
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Pretreatment of hops for further processing in beer technology
Tichá, Anna ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with pre-treatment of hops for further processing in beer technology. In the experimental part of the work, the effect of low temperatures, as pre-treatment of hops, on the monitored parameters was observed. Three types of cold pretreatment were used. In two cases, the hop material was frozen using a freezer at -25 ° C and in the second case at -70 ° C. In the third case, the hop material was treated by contact with liquid nitrogen in combination with mechanical treatment. The variety of hop materiál was Žatecký poloraný červeňák, which were in the form of pellets or pressed hop cones. The total bitterness of the samples, the total content of phenolic substances, the total content of flavonoids, the antioxidant activity and the concentration of essential oils, specifically myrcene humulene and geraniol, were examined. The effect of pre-treatment was investigated during conventional worth boiling as well as dryhopping. The experimental part includes descriptions of the hopping process, descriptions of individual analytical methods. A parallel measurement was performed on each sample. Significant advantages or disadvantages of some of the pretreatments were not demonstrable, however, the most significant differences were observed in samples hopped with hops pretreated by freezing at -70 ° C, which had a positive effect on the amount of extracted essential oils during cold hops.
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Evaluation of the influence of the pasterization and filtration on selected chemical components of beer
Vopelková, Dominika ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
The aim of this work was to study the influence of the pasteurization and filtration on selected chemical compounds in beer. Specifically, the influence on elemental composition, content of organic acids, carbohydrates and phenolic substances was studied. Optical emission spectrometry with inductively coupled plasma (ICP-OES) was used for elemental analysis of beer. Analysis of organic acids was evaluated by Ion chromatography. For analysis of carbohydrates was used High performance liquid chromatography with ELSD detector (HPLC-ELSD), phenolic compounds was evaluated by HPLC with diode array detector (HPLC-DAD). Data from analysis of beer was performed by usage of statistical methods (analysis of variance and principal component analysis). Parameters that showed the most significant differences between individual groups of beers were obtained. Correlations between the variables and the technological beer processing operations were found. 12 parameters of total 23 were affected. The effect of filtration and pasteurization was observed in content of the iron, silicon, potassium and magnesium, malate, monosaccharides glucose and fructose and phenolic compounds.
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Determination of selected parameters in the Czech lager beer
Žáková, Kateřina ; Gregor,, Tomáš (referee) ; Diviš, Pavel (advisor)
The topic of this bachelor thesis is to establish an concentration of selected substances at czech beers lager type. In the first part of the work there are in a range of the theory described basic materials for a beer production and its production proces too. A large part is dedicated to describing of analytical methods used for an analysis of choosen phenolic substances, organic acids and inorganic substances (elements). In the experimental part the measured results are discussed. The target of this work was to compare a composition and to find specific or characteristic ingredients in selected brands type lager produced in Czech republic. Further there were compared the samples with the Czech Beer designation and the samples without those signing.
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Determination of beta-glucans and pentosans in raw materials for production of beer and in beer
Piškulová, Lenka ; Sachambula, Lenka (referee) ; Mikulíková, Renata (advisor)
The content of beta-glucans and arabinoxylans in barley grain, malt and wort was monitored. The varieties of barley were Pionier, Libuše, Manta, Tango, KWS Amadora, Kampa, KWS Irina, Francin, Odyssey, Overture, Vendela, Petrus, Laudis 550, Sunshine, Kangoo, Xanadu, Sebastian, Bojos and Malz. These varieties were grown on three different habitats (Uherský Ostroh, Věrovany and Vysoká u Příbramě). The content of beta-glucans and arabinoxylans was also analysed in five different types of beer. In brewing and malting industry the content of beta-glucans and arabinoxylans is mainly monitored because of their negative influence on decanting of wort and filtration of beer. These substances can contribute to turbidity and precipitation in beer and thus negatively effect the stability of beer. The content of beta-glucans in barley grain, malt, wort and beer was determined by FIA method and the content of arabinoxylans was determined in barley grain, wort and beer by Douglas method. The highest content of beta-glucans in barley grain was found in 14/19 varieties at Uherský Ostroh, where the amount of beta-glucan content was in the range of 3,65-5,60 %. The highest beta-glucan content in malt was found in 17/19 varieties at Vysoká u Příbramě, where the beta-glucan content was between 0,15-0,79 % and the highest content of beta-glucans in wort was found in 16/19 varieties also at Vysoká u Příbramě. There was the beta-content in the range of 22-184 mg/l. The results of content of arabinoxylans in barley grain and wort were more balanced. The highest content of arabinoxylans in barley grain was found in 10/19 varieties at Věrovany. The content of arabinoxylans at this habitat was in the range of 3,04-4,56 %. The highest content of arabinoxylans in wort was determined in 8/19 varieties at Uherský Ostroh. The content of arabinoxylans at this habitat was in the range of 542-1040 mg/l. The highest content of beta-glucans in samples of beer was determined in a sample of light lager (207 mg/l) and the highest content of arabinoxylans was found in a samle of wheat lager (1465 mg/l).
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Draft beer analysis by HPLC-ELSD and IC
Vanduchová, Petra ; Vespalcová, Milena (referee) ; Diviš, Pavel (advisor)
In this bachelor thesis is discussed the brewing process and composition of the beer. The experimental part deals with analysis of polyphenolic compounds and carbohydrates by HPLC, analysis of organic acids by the IC and the ICP-OES method was used for analysis of elements. The HPLC method was used to determine eleven polyphenols. Gallic acid was the most represented compound of polyphenols and quercetin was the least represented compound. Glucose, fructose and sucrose were analysed by HPLC and the most represented compound of carbohydrates was glucose. The ICP-OES method was used to determine ten elements. Zinc was the least represented element in the analysis and phosphorus and potassium were the most represented in the analysis.
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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
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