National Repository of Grey Literature 43 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Bioflavouring of beer using new Czech hop varieties
Ondruch, Petr ; Diviš, Pavel (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis focuses on bioflavouring of beer using new czech hop varieties. Dry hopping is a phenomem, that contributes to the attractiveness and diversity of beer and is nowadays gaining in popularity. The aim of this work was to determine the effect of dry hopping on sensory profile and analytical parametrs of dry-hopped beers using czech hop varieties. Sensory evaluation and chemical analysis of these beers were taken. The chemical analysis included determination of the basic beer characteristics, total phenolic a flavonoid content, antioxidant activity and the concentration of selected organic acids and chemical elements. It was found out that dry-hopped beers compared to the reference beer presented higher bitterness, antioxidant activity and contained higher amount of flavonoids. Also an increase in pottasium, manganese, copper, calcium and malic acid levels was reported. The pH of beer samples was not affected by dry hopping. Sensory evaluation showed that dry hopping had a positive influence on the overall enjoyment of the beer, which was mainly determined by the higher aroma and more intense bitterness. By summaring all the data, it is obvious that dry hopping of beer using new czech hop varieties has a positive effect on the quality of the final beer and these hop varities are suitable for further use in the beer industry.
Effect of the dry hopping of the stability of beer foam
Benda, David ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with the influence of dry hopping on the stability of the beer foam. It was observed how this effect affected general characteristics of beer, the content of hop bitter acids, proteins, phenolic compounds, selected micro- and macro elements, organic acids and the stability od the beer foam. Theoretical part characterises raw the materials for beer production, the substances affecting the stability of beer foam and the beer brewing process. Furthermore the beer foam is described froam a physical point of view together with the steps of its formation and drainage as well as other phenomena that lead to its disappearance. A detailed description of used analytical methods is included. The experimental part illustrates the preparation of the model beer and the implementation of dry hopping with the Czech hop variety called Kazbek. Dry hopping was carried out on day 3, day 5 and day 10 with a 3 g/l and a 6 g/l hop dose. The prepared beer was subsequently analysed for general characteristics, the beer foam stability, bitter hop acids, phenolic compounds, protein, selected micro- and macroelements and organic acids. Based on the measured data, there were found correlations between the observed beer parameter and the stablity of the beer foam. The results revealed that dry hopping in beer increases the content of the phenolic compounds and bitter substances, but its effect on the beer foam stability is negative.
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.
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.
Influence of raw materials on qualitative indicators of various types of craft beer
HEJTMÁNKOVÁ, Zdeňka
Abstract The Bachelor's Thesis considers basic ingredients necessary for producing beer. In the first part, raw materials like hop, brewer's yeast, water, malt and its substitutes are dealt with. Regarding hop, the seed cone along with its chemical composition is discussed. Significant varieties grown in the Czech Republic are mentioned as well as selected foreign varieties of hop. Not least, packaging and storage of hop is described. Similarly with malt, where types of malt are listed and evaluation of quality given. The thesis contains also types of water suitable for producing beer. An indispensable ingredient for production of beer is brewer's yeast differentiated as top-fermenting and bottom-fermenting yeast. As an aside, the chemical composition and propagation of yeast is mentioned. In the last part, sorts of craft beer are discussed focusing on qualitative indicators of certain sorts of beer.
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.
Comparison of qualitative indicators varieties of hops (Humulus lupulus) from various types of hop fields
KORCOVÁ, Žaneta
The aim of this thesis was to determine content of - a -bitter acids in samples of hop obtained from different types of growing regions. Object of research were cultivars of Saaz late, Sládek and Premiant cultivated in three growing regions (Žatecko, Úštěcko, Tršicko) in year 2015. Nine hop samples from conventional agriculture and one from bio production were examined. For all growing areas, from which hop cones were obtained, was determined altitude, rainfall and average temperatures during vegetation period. Quantity of bitter acids were measured by HPLC. Our calculated correlation coefficients showed that the higher altitude and average temperature the lower content of bitter acids was measured and more precipitation has positive impact on content of bitter acids.
Technology of growing hops (Humulus lupulus L.). Elicitors influence on yield and product quality. His food and non-food use.
HAŠKOVCOVÁ, Petra
This thesis deals with growing hops technology, its use, the use of elicitation and herbal products for agricultural crops. The general part of the thesis deals with the history of hops, the morphology of the hop plant, hop growing technology, nutrition and fertilization, pest and disease control, harvesting and chemical composition of hops. The Czech Republic is traditionally one of the world's largest hop producers. Czech hops is world renowned for its quality, given by the absolutely predominant fine aromatic sort Žatecký poloraný červeňák. (ŽPC). Furthermore, this part provides information about the impact of elicitation on agricultural crops, the effect of herbal preparations and the use of hops. The last part summarizes the basic information about the common hops.

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