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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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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 hop quality from traditional and non-traditional region of cultivation
NOVÁKOVÁ, Renata
In this thesis, "The Evaluation of the Quality of Hops from Traditional and Non-traditional Growing Areas", the quality of three varieties of hop seed cones (Saaz, Sladek and Kazbek) from a non-traditional hop-growing region was analyzed and the data used for comparison. The primary aim of the study was to determine if there is a possibility of growing quality hops in a region that is not considered a hop-growing region. The hops that were tested were harvested in 2015 from a private hopfield located in Obora near Tábor. This hopfield is owned and managed by Ing. Martin Novák. Mechanical and chemical analysis was carried out on samples from Obora. The main goal of the analysis was to determine the alpha and beta acid content of the hop seed cones harvested there. Samples were analyzed with EBC 7.7 (HPLC). Alpha acid content of the tested samples in Saaz hops was 4.06 % w/w, in Sladek 7.14 % w/w and in Kazbek 4.67 % w/w. The content of beta acids in Saaz hops was 3.16 % w/w, in Sladek 3.93 % w/w and in Kazbek 4.51 % w/w. The collected data was then compared to published data for hops grown in traditional hop-growing regions. Alpha acid content was found to be higher in the hops grown in Obora, while beta acid content was lower.
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