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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.
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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.
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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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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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The influence of type of dry hopping on the senzomic and sensory profile of top fermented beer
Bečková, Alena ; prof.Ing.Pavel Dostálek, CSc. (referee) ; Olšovská,, Jana (advisor)
The thesis is focused on the effect of dry hopping on beer senzomy and sensory profile of the top-fermented beer. The goal of this work was to modify samples of the top-fermented beer by dry hopping, to analyze them by senzomy and sensory way, to optimize the method for hop essential oils analysis and to compare the results to the available literature. The problematics of the used raw materials, analyzed substances, technological and analytical methods are discussed in the theoretical part. The practical part is composed of technological preparation of the samples and their analysis. There was used a commercial product of the type of American Indian Pale Ale in this work. There was added a Cascade hop by dry hopping into the commercial product. The basic analysis of gravity and attenuation of the beer were done on the fresh beer and the two months old beer. The selected essential oils, carbonyl compounds, bitter acids, selected metal contaminant and nitrates were established in the beer and in the hop. The samples of the beer were sensory evaluated in the same two-month interval. It was determined that the dry hopping influenced the increased pH of the beer. There was established the quantity of essentials oils in the samples and it was compared to the sensorial results. These results can be used as a base for the next exploration, some part of the results are applicable in the beer industry.
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Bioflavouring of low alcoholic beer by dry hopping
Dušánek, Václav ; Mikulíková, Renata (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the influence of cold hopping of low-alcohol beers on analytical properties and sensory profile of beer. The effect of cold hopping was observed using the varieties Kazbek, Jazz, Mimosa and Uran. In the experimental part, the production process of low-alcohol beer using immobilized yeast is described. After the main fermentation, the low-alcohol beer was kegged into five cuvettes and after 20 days cold-hopped at a dose of 3 g/l with individual varieties. The effect of cold hopping with individual varieties on the organoleptic properties of the beer was observed. Bitterness was determined, with cold-hopped beers showing an increase between 17-24 % in bitterness. Furthermore, the ethanol content was determined by high-performance liquid chromatography at 2,14 % vol. A significant increase in all volatiles, in particular -myrcene and linalool, was found in the cold-hopped beers by gas chromatography with mass spectrometry. The sensory analysis showed that the cold hopping had a positive effect on the overall impression and masked the taste defects of the reference low-alcohol beer. The best hop evaluated for the use of the cold hopping method was the Kazbek variety. The Jazz and Mimosa varieties were also perceived relatively positively by the evaluators. On the other hand, the Uran variety achieved a worse overall impression than the reference beer.
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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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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.
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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.
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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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