In this paper, we have collected and presented a wide field of hop processing with extraction processes into various forms, intended for specific needs. We went into detail about the availability and suitability of analytical techniques used to determine the composition and physical properties of the extracts obtained.
COBISS.SI-ID: 22103062
The fermentation was monitored during the production of twelve batches of beer, where the starter yeast culture was reused twelve times without any further treatment. The work was conducted on an industrial scale employing standard process conditions. Monitoring of the starter culture viability during successive fermentations indicated no reduction in the viability and vitality of the yeast culture. Monitoring of the fermentable wort saccharide concentrations (glucose, fructose, disaccharides and trisaccharides) revealed a correlation between an improvement in saccharide utilisation and starter culture age. Saccharide uptake efficacy proportionally matched the repitching frequency. Successive exploitation of S. pastorianus starter culture has a positive impact on the dynamics of saccharide utilisation from classical hopped wort and the young beer. Furthermore, the final lager beer contains no residues of fermentable saccharides that could affect the overall quality and flavour profile.
COBISS.SI-ID: 56769795
The sensory profile of beer is influenced by the hop variety and hopping technology. This study examined pale lager beers, hopped in the kettle with (or without) single dry hopping. Seven Slovenian, four Czech and one American genotypes were used to determine the impact of dry hopping on the sensory and volatile profiles of beer. Descriptive and bitterness lingering assessment sensory methods were used. The essential oil composition of the hops and beers was accessed using GC/MS so as to clarify their correlation to sensory profiles of both brewing processes. Changes in essential oils and aroma profiles of beer related to storage were evaluated. Results showed differences among the genotypes in the hop oil profiles in the kettle-hopped beers. Based on the hop dose, dry hopping increased the monoterpene alcohol and monoterpene hydrocarbon content. Hop-derived aroma profiles of the genotypes differed. Dry-hopped beers tended to have a more bitter aftertaste than solely kettle-hopped beers. Both kettle and dry hopped beers of all genotypes showed good sensory acceptance. After storage of beer, the content of most essential oils and hoppy flavour significantly decreased. The sensory aging of the kettle and dry hopped beers was comparable.
COBISS.SI-ID: 4452652
Although beer evaluation runs with sensory experts, we cannot neglect the influence of the human factor and subjectivity. This problem could be solved with chemical analysis of the volatile part of beer aroma from which we can build a data bank for construction a model to classify samples comparable to sensory assessment. 22 batches of the same beer brand were assessed for sensory and chemically described with the contents of alcohols and esters,hop essential oils compounds by GC and other aroma volatiles, analysed by head space SPME-GC/MS. The best matchings of 91 % regarding samples classification on the base of chemical analyses to sensory scores were achieved with a data set of results from HS-SPME and higher alcohols and esters analyses by RDA. Results shows that deviations in beer aroma are not a consequence of a permanent repeatable error in brewing process and are not influenced by raw materials but are the consequences of the alcoholic fermentation.
COBISS.SI-ID: 910455
Hops’ unique composition of essential oil components and bitter resins are crucial for beer aroma, which is important to consumers’ acceptance of beer. In this experiment the same wort was divided into four portions and each was hopped differently. To determine the dynamics of isomerization rates the concentrations of alpha-and iso-alpha-acids were continuously measured. Measurements of hop essential oil components were performed during each process to understand the dynamics of the transition into beer. Longer boiling increased the reduction of iso-alpha-acids, as well as essential oil components. Dry hopping also affected not only on beer aroma but also on beer bitterness.
COBISS.SI-ID: 36221955