Evaluation of Czech Hops Harvested in 2014 – Part I: Contents of α- and β-Bitter Acids

The contents of α- and β- bitter acids from hops harvested in the Czech Republic in 2014 have been evaluated. Samples originated from all growing areas – Žatec, Úštěk and Tršice (77.3%, 10.6% and 12.1% of the hop garden areas in the Czech Republic). The main varieties, Saaz (Žatecký poloraný červeňák, ŽPČ), Sládek, Premiant and Agnus were cultivated on 87.2%, 6.0%, 4.2% and 0.9% of the harvest areas respectively. Samples were analyzed in accordance with the Analytica EBC, method 7.7 (HPLC), all results are given in weight% in dry matter. The average value of α-bitter acids in the Saaz hops was 0.38% (9.2% rel.) and 0.66% (18,3% rel.) lower when compared to the year 2013 and to the average of the 21 years respectively. The content of β-bitter acids was 0.76% (16.0% rel.) higher when compared to the year 2013 and 0.37% (7.9% rel.) lower to the long-term average. The content of α-bitter acids in the Sládek hops was 0.37% (6.0% rel.) and 0.95% (14.0% rel.) lower when compared to the harvest in 2013 and to the average of the 11 years respectively. The content of α-bitter acids in the Premiant hops was in 1.13% (13.5% rel.) and 1.97% (21.4% rel.) lower when compared to the harvest in 2013 and to the average of the last 11 years. The content of α-bitter acids in the Agnus hops was 1.47% (13.2% rel.) and 1.74% (15.2% rel.) lower when compared to the harvest in 2013 and to average of last six years

Analysis and prognosis of bitter acids content in Czech hop varieties - year 2018 and long-term comparisons and trends

This article presents the results of the harvest forecast of the alpha- and beta-bitter acids of the Czech hop varieties in the 2018 harvest, the results are discussed in relation to the long-term averages, the composition of the bitter acid analogs and the stability of the varietal characteristics. 180 hop samples were analyzed using EBC 7.7 (HPLC) method. The alpha-acid content of the most important Saaz variety (2.9% in dry matter) was identical to the 2017 harvest and 18% rel. lower than the 26-year average. The alpha-acid content of Sladek (5.0%), Premiant (4.8%), and Saaz Late (1.6%) varieties was significantly lower than the long-term average. The harvest of the hops of the Kazbek and Agnus varieties was close to the long-term average. The ratio of alpha- and beta-acids, the relative content of cohumulone and the relative content of colupulone were consistent with long-term averages for the tested varieties. It was confirmed, that the harvest forecast gives timely information on the alpha-acids content of the harvest, the results were in good agreement with the values of the final evaluation of all harvested hops samples

Study on the effect of malt and decoction mashing on polyphenols and antiradical power of wort

Mashing is one of the key operations in beer brewing. Together with polyphenolic compounds it can affect the quality and stability of beer. In our pilot brewing trials of pale lager (200 L), malts of three barley varieties were compared using either infusion or double decoction mashing. Total polyphenols, anthocyanogens and flavanoids were determined in sweet and hopped wort. Free phenolics were measured by HPLC coupled with coulometric detection. Antiradical power was determined by RC-DCPI, ARA-DPPH and ESR-T150 methods. In this way the influence of mashing method and barley variety on polyphenols and antiradical activity of sweet wort was demonstrated showing that the effect of mashing was stronger (ANOVA). The results showed significantly higher, i.e. by tens of per cent, levels of all polyphenols studied in both the decoction sweet wort and hopped wort. The decoction process resulted in higher levels of the antiradical power, ARA-DPPH (37–47%) and RC-DCPI (25–60%). A cluster analysis partitioned 28 free phenolic compounds in sweet wort primarily by variety and secondarily by mashing. The Malz malt showed a greater increase in polyphenols, free phenolic compounds and antiradical power in the decoction process compared to the Bojos and Sebastian malts. Decoction mashing introduces higher levels of phenolic antioxidants into the beer with the potential to improve the sensory stability of the beer and provide health benefits to the consumer. The different behaviour of malts and barley varieties needs to be better elucidated in further research

Determination of Rebaudioside A in Mixed beer, Beer-based Beverages and Lemonades

The plant Stevia rebaudiana (Stevia sweet) is becoming a favourite sweetener in the food industry. Sweet taste is caused by diterpenic glycosides, so-called steviol glycosides, which lack calories while being 300 times sweeter than sucrose. While all the other glycosides are slightly or even disagreeably bitter, rebaudioside A possesses desirable sensorial properties. Because this sweetener is used to sweeten beverages including mixed beer, a fast routine analytical method was developed using HPLC with UV detection for determination of rebaudioside A in mixed beer and lemonade. The HILIC principle, which is suitable for separation of polar and hydrophilic analytes, was used for separation of steviol glycosides. The method is selective, reproducible and has a high recovery of 90–100 %

Determination of Sugars and Saccharides in Beer

The concentration of total saccharides including polyols and sugars belongs to one of the main values of basic nutrition labelling information of food as well as beer. The article informs about the method of these compounds, describes its chemical and analytical principles, validation parameters and clearly explains how the method is applied in the beer analysis

Evaluation of α- and β-bitter Acids Content in Harvest of Czech Hops in 2016

The contents of α- and β-bitter acids from hops harvested in the Czech Republic in 2016 have been evaluated. Samples originated from all growing areas – Žatec, Úštěk and Tršice (77.3%, 10.7% and 11.9% of the hop garden areas in the Czech Republic). The tested varieties, Saaz (ŽPČ), Sládek, Premiant, Agnus, Kazbek and Saaz Late were cultivated on 87.8%, 5.6%, 3.7%, 0.8%, 0.4 and 0.9 of the harvest areas respectively. Samples were analyzed in accordance with the Analytica EBC, method 7.7 (HPLC), all results are given in weight % in dry matter. The average value of α-bitter acids in the Saaz hops (3.35%) was 1,20% (55.8% rel.) when compared to the year 2015 and 0.20% (5.6% rel.) lower to the average of the 23 years. The content of β-bitter acids (4.99%) was 1.75 % (54.0% rel.) and 0.33 % (7.0 % rel.) higher when compared to the year 2015 and to the long-term average respectively. The content of α-bitter acids in the Sládek hops (7.29%) was 2.20% (43.2% rel.) and 0.64% (9.6% rel.) higher when compared to the harvest in 2015 and to the average of the 13 years respectively. The content of α-bitter acids in the Premiant hops (9.02) was in 2.43% (36.9% rel.) higher when compared to the harvest in 2015 and comparable to the average of the last 13 years. The content of α-bitter acids in the Agnus hops (9.70) was in 0.80% (7.6% rel.) and 1.40% (12.6% rel.) lower when compared to the harvest in 2015 and to average of last 8 years. The content of α-bitter acids in the Kazbek (4.96%) and Saaz Late (4.76%) varieties was in comparison with the harvest in 2015 0.37% (8.1%rel.) and 2.6% (119% rel.) higher. The ratio α/β bitter acids, the relative content of cohumulone in the total α-bitter acids and the relative content of colupulone in the total β-bitter acids were also in agreement with the long-term averages found for the tested varieties

Sensory Beer Aging

A sensory aging of beer occurs during the beer transport to a customer and its storage; this is due to irreversible chemical processes and is manifested by adverse change in the organoleptic character of the beer. Sensory beer aging results in the evolution of the old flavor of the beer, which is a combination of many foreign fl avors and fragrances. The development of substances responsible for these sensory changes (especially carbonyl compounds) can be affected by storage, particularly by access to oxygen, light, vibrations, and temperature of storage. In our study we selected carbonyl compounds which can be regarded as indicators of aging of Czech lager, including 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, furfural and phenylacetaldehyde. We obtained temporal profi les of their evolution under various conditions of storage and the correlation with the development of the old beer fl avor. The time dependences so obtained provided an interesting fact, namely that the product of Maillard reactions during beer aging exhibits a linear increase and the product of Strecker degradation of amino acids show a nonlinear dependence on the length of aging. These findings will be used to create chemico-statistical methods for determining the degree of sensory impairment of beer. The method will be used also for backward determination of storage conditions and even of beer sensorially damaged due to improper storage conditions

Determination of Bitter Compounds in Hops – Effect of Crop Year and Hops Age

Our study is focused on mutual comparison of four methods of determination of alpha acids in hops (EBC 7.4, EBC 7.5, ČSN and EBC 7.7) and their application in evaluation of hops stored under different conditions. Furthermore, the results of the comparison of predicted and actual alpha acid values in the long-term monitoring of harvesting of three Czech hop varieties are discussed. The largest differences were found between the EBC 7.5 (LCV) and EBC 7.7 (HPLC) methods; the first method gives systematically higher results and the difference exponentially increases with the hop storage index (HIS) value. The difference in HSI in fresh hops is 10 – 15% rel. while the difference in older hops with HSI 0.6 – 0.7 is 25 – 45% rel. Pre-harvest prognosis and harvest estimate of alpha acids in the Saaz variety are in good agreement with the facts (kr = 0.93, kr = 0.95) and the same holds for the harvest estimation relation and the reality of the varieties Sládek and Premiant (kr = 0.93; 0.97)

Kazbek – The First Czech Aroma “Flavor Hops” Variety: Characteristics and Utilization

The world market of craft beer, especially dry hopped beers, has been constantly growing in the last few years. That is why new varieties of hops are still being bred. This article gives the genetic, agronomic, chemotaxonomic and brewing characteristics of Kazbek, the first “flavor hops” variety bred in the Czech Republic. Kazbek genetically belongs to a group of bitter American hops resulting from Brewers Gold variety, but the alpha acids content is relatively low, 5.0–8.0% by weight. The content of a homologous series of geranyl esters (acetate – propionate – isobutyrate) in an amount 2–4% of total essential oils (1–1.5 g/100g) is considered to be the originator of the specific, mainly citrus-like aroma of Kazbek. Moreover, the essential oil fraction contains about 25 sulfurous substances, predominantly thioesters. In the pilot scale brewing tests, the quality of Kazbek hops was proved both in kettle and dry hopping of Pilsner lagers. The overall sensory impression of kettle hopped lagers was comparable to Saaz hops, the differences were in the character of hop-derived flavor and bitterness. The best results of dry hopped beers were achieved for a 2.5 g/l hop dose and a contact time of 3 days