Submitted by JOÃO OLAVO FIGUEIREDO QUELHAS null (olavofq@gmail.com) on 2017-03-29T23:13:49Z No. of bitstreams: 1 João Olavo Quelhas.pdf: 2589215 bytes, checksum: 6917db55e488c1ded8443d00719d55c9 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-03-30T18:36:37Z (GMT) No. of bitstreams: 1 quelhas_jof_me_sjrp.pdf: 2589215 bytes, checksum: 6917db55e488c1ded8443d00719d55c9 (MD5) / Made available in DSpace on 2017-03-30T18:36:37Z (GMT). No. of bitstreams: 1 quelhas_jof_me_sjrp.pdf: 2589215 bytes, checksum: 6917db55e488c1ded8443d00719d55c9 (MD5) Previous issue date: 2017-03-17 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O crescimento da produção de cerveja artesanal no Brasil e a consequente utilização de antigas técnicas de produção, como a lupulagem a frio (dry-hopping), esquecida pelas grandes empresas e pouco estudadas, abrem espaço para estudos sobre o melhoramento destas técnicas. Considerando a importância do lúpulo na produção de cerveja, principalmente seu alto teor de compostos considerados bioativos, por exemplo as procianidinas, a lupulagem a frio pode ser uma notável fonte de melhoramento nos aspectos sensoriais da cerveja, assim como no conteúdo de compostos com possíveis benefícios à saúde. Primeiramente, foi analisada a atividade antioxidante, pelos métodos de DPPH e ABTS, de sete variedades de lúpulo (Cascade, Fuggle, Tradition, Saaz, Centennial, Herkules e Magnum), com a finalidade de escolher uma para ser utilizada na lupulagem a frio. O Cascade foi selecionado para utilização na lupulagem a frio, principalmente por ser o atualmente o lúpulo mais produzido e consumido mundialmente. A produção das cervejas se diferenciou apenas na etapa da maturação, onde ela foi dividida em 17 recipientes. Cada cerveja maturou sob diferentes temperaturas (de 0 a 10°C), tempos de contato do lúpulo com a cerveja (de 0 a 20 dias) e concentrações de lúpulo (de 1,5 a 3 gL-1), seguindo um delineamento composto central rotacional, com três repetições do ponto central. As 17 cervejas foram analisadas físico-quimicamente em relação ao extrato original/primitivo, extrato aparente, atenuação aparente, teor alcoólico, amargor, cor, pH, turbidez, compostos fenólicos totais e atividade antioxidante (DPPH e ABTS). Foi realizada também uma análise sensorial, avaliando aceitação pela cor, aroma, sabor e amargor, além da aceitação global. As variáveis analisadas durante a lupulagem a frio não apresentaram influência no produto final em relação as analises físico-químicas e a aceitação sensorial. / The growth of craft beer production in Brazil and the consequent use of old production techniques, such as dry-hopping, forgotten by the large companies and little studied, open space for studies to improve these techniques. Considering the importance of hops in beer production, especially their high content of compounds considered bioactive, for example procyanidins, dry-hopping might be a notable source of improvement in the sensorial aspects of beer, as well as in the content of possible healthy compounds. Firstly, the antioxidant activity of seven hop varieties (Cascade, Fuggle, Tradition, Saaz, Centennial, Herkules e Magnum) was analized by DPPH e ABTS, in order to choose one to be used in the dry-hopping. Among the analyzed hops, the Cascade type was selected and, therefore, used during the dry-hopping process, mainly because it is currently the most produced and consumed hop worldwide. The brewing process was the same until the maturation, when the beer was divided into 17 containers. Each beer matured under different temperatures (from 0 to 10°C), time of contact between beer and hop (from 0 to 20 days) and hop concentration (from 1,5 to 3 gL-1), following a central rotational design, with three replicates of the central point. The 17 beers submitted to physicochemical analysis as original/primitive extract, apparent extract, apparent attenuation, alcohol content, bitterness, color, pH, turbidity, total phenolic compounds and antioxidant activity (DPPH and ABTS). A sensory analysis was also implemented, evaluating the attributes: color, aroma, flavor, bitterness and global acceptance. The variables analyzed during dry-hopping did not show any influence on the final product in the physical-chemical analysis and sensory acceptance.

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.

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.

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.