Dry Hopping Research Articles

Chemical and sensory profile of lager beers hopped with new Czech bitter varieties Boomerang and Gaia

Characterising the sensory profiles of beers made from new hop varieties is of considerable importance for their application in brewing. New Czech bitter varieties Boomerang and Gaia were tested in three-year pilot brews (200 l) of 12% single-hopped pale lager, produced in kettle and kettle+dry-hopped variants. The hop-derived aroma and bitterness profile of the beers was evaluated using a comprehensive descriptive method. Hop-related volatiles in beer were determined by GC/MS-MS method. Both of these bitter varieties showed a pleasant bitterness profile even in dry-hopped beers. The overall impression of the beers from the varieties tested was favourable, at the level of the control beer (Saaz). The profile of hop derived volatiles and aroma in beers from Gaia and Boomerang varieties were different. The results show the potential of Boomerang for both single kettle-hopped beers and dry-hopped lagers due to its interesting aroma profile (spicy, herbal, floral). The Gaia variety can be used in a similar way, with a preference for dry hopping to give a well-balanced hop-derived aroma profile. Both varieties have shown considerable potential for the production of new beer brands, and their drought tolerance may also help their widespread cultivation.

Effect of Dry Hopping Conditions on the Hop Creep Potential of Beer

Dry hopping is a technique of adding hops to beer during or after fermentation to enhance aroma and flavor. It results in an undesired phenomenon called hop creep: attenuated beer undergoes a secondary fermentation. The aim of the research was to evaluate practical aspects of hop creep. In laboratory conditions hop creep was evaluated in pasteurized and unpasteurized beers and the effect of hop separation from beer after 3 days of dry hopping was verified. Hop creep analyzed in beers brewed on a pilot scale (20 L) and an industrial scale (10 hL) allowed to observe the course of hop creep in various scales of production, and to compare the process in pressure and non-pressure conditions. The decrease in the apparent extract of beer caused by hop creep occurs only in unpasteurized beers, separation of hops after 3 days reduces the extent of hop creep. Hop creep occurs faster in top-fermented beers and is equally intense regardless of the scale of production. The use of pressure conditions during dry hopping extends the duration of the hop creep without affecting the final extract content of the beer (the final attenuation of beer is the same in pressure and non-pressure conditions).

Characterization of Brazilian Cascade and Chinook hops and their dry-hopped beer

The flowers (cones) of Hop (Humulus lupulus L.) have extensive applications in the brewery industry and in Brazil, 98% of which is imported. The Brazilian cultivated hops have multiple flowerings, and therefore the cone cultivation period could be shortened. Herein, Cascade and Chinook whole cones cultivated in Brazil were analyzed and compared with American pellets. Following the European Brewery Convention (EBC) methodology, the contents of alpha acids, polyphenols, and essential oils were quantified and used as comparison criteria. Amidst the Brazilian Cascade essential oils, isoamyl propanoate and 6-methyl heptanoate were identified, both of which were responsible for pineapple aromas and were absent in American pellets. The dry hopping (DH) process promoted higher alcohol beverage value, lower dissolved oxygen, and higher polyphenol values. In comparison with the commercial counterpart, the Brazilian Cascade hops presented similar characteristics, but with different organoleptic properties (terroir), inherent to their growing place. The resulting terroir adds value to the Brazilian Cascade usage, considering the DH overall process and the application in special beers.

Valorization of Spent Hops from Dry Hopping for Bittering of Pilsener Style Beer

In the last decade production of dry hopped beers increased considerably. Dry hopping results in significant amounts of spent hop material (mixture of beer and hop vegetative matter), which is mostly regarded as waste and is discarded. During dry hopping polar (aroma) compounds are extracted into beer, while nonpolar compounds such as humulones largely remain in the spent hops. In this study, spent hops from local craft breweries were collected. They were analyzed towards dry matter (d.m.), surplus beer content, their concentration of humulones, and iso-humulones, and were then used as the sole source of bitterness in the production of Pilsener Style beer. It was found that humulone concentrations in spent hops ranged from 1 to 10.3% dry matter, which corresponds to retention rates of 28 to 94%. Wort and beer samples made from selected spent hop samples were analyzed using a range of physicochemical analyses, along with sensory evaluation of both fresh and aged beers. Beer analysis showed that the targeted bitterness (30 BU) was successfully achieved in most brews. Sensory analysis confirmed the good overall quality of spent hop beers as such and also in comparison with a reference brew using hop pellets. In summary, spent hops can be valorized by substituting hop pellets in the kettle, leading to reduced beer losses, savings on hop pellets, increased sustainability and hence reduction of production costs.

Co-fermentation of lactic acid bacteria and S. cerevisiae for the production of a probiotic beer: Survival and sensory and analytical characterization

The effects of boiling stage hopping or dry hopping methods; the use of Bobek or Crystal hop varieties; and the usage of just Sacharomyces cerevisiae yeasts or co-fermentation with Lactobacillus plantarum bacteria on the production of a probiotic beer have been studied. Only the cell viability levels registered for Lactobacillus plantarum bacteria in those beers produced by dry hopping, after an initial inoculation of 10 million cells per mL in both beers hopped during the boiling stage and in dry-hopped beers, were higher than those generally considered as minimum to provide health promoting benefits. With regard to polyphenols, higher concentrations were generally obtained in the beers produced by co-inoculation, whereas with respect to volatile compounds, co-inoculation with Lactobacillus plantarum and the employment of the dry hopping method with Bobek hops resulted in the beers with the highest contents. The sensory profile of the beers was clearly influenced by the hopping method, so that dry-hopped beers were awarded significantly higher scores with respect to certain fruity (stone fruit and tropical fruit, p < 0.05) and floral descriptors (p < 0.05), while they were ranked at a lower level regarding their cereal and toasted descriptors. The hopping method was the most influential on the composition and sensory properties of the final beers whereas the co-fermentation did not substantially modify any of them.

Impartment of spicy, fruity and herbal aromas from the Czech hop varieties of Ceres, Pluto and Saturn to beer

The aim of the study is to evaluate the intensity and character of the beer aroma in selected hop varieties. In 2022 and 2023, new Czech Flavour hop varieties of Ceres, Pluto, and Saturn were registered. Ceres exhibits a mild citrusy and fruity hop aroma. Pluto has an intense fruity and herbal aroma, while Saturn has an intense fruity aroma with a milder citrus note. Differences in the intensity and character of the beer aroma were identified based on the hop variety used and the cold hopping dose. These varieties and their combinations were tested under cold hopping at 3 g/l and 6 g/l to assess the impartment of the aromas to beer. The combination of Pluto + Saturn shows the highest intensity of a spicy aroma, while Ceres exhibits the highest intensity of both the fruity and herbal aromas – all this at 6 g/l. The best character of the spicy aroma is observed with Ceres at 3 g/l. Ceres also demonstrates the best character of the fruity aroma, and Ceres + Pluto combination excels in the herbal aroma, both at the dose of 6 g/l. The popularity of beer is crucial, with the combination of Ceres + Pluto at 3 g/l proving to be the most popular. The results have practical applications in breweries producing bottom-fermented beers that utilize dry hopping. It is obvious which hop varieties or their combinations can be used to accentuate individual aroma profiles.

Industrial Multiple-Effect Fractional Condensation under Vacuum for the Recovery of Hop Terpene Fractions in Water.

The inflorescences of Humulus lupulus L. are the most valuable ingredient in the brewing industry. Only female cones are used as their bitterness and aroma, much associated with beer, are granted by the production of resins and essential oils, respectively. The traditional brewing process for the extraction of the organic volatiles in hops is called dry hopping. It consists of extended maceration at low temperature after the fermentation phase. New extraction technologies can improve extraction rates and product quality while saving time and money. This article proves that multiple-effect fractional condensation under a vacuum is suitable for flavouring applications and especially for performing dry hopping without contamination risks and reductions in hop amounts. This technique leads to the recovery of aqueous aromatic fractions that are very rich in hop sesquiterpenes and monoterpenes. These suspensions are extremely stable when stored at 5-8 °C and avoid degradation even after several months. This feature is crucial for the marketing of non-alcoholic beverages, where the dilution of essential oils is otherwise problematic.

Study of the influence of hops on the safety of brewing semi-products

In order to ensure quality control and food safety, the in vivo effect of hops on the frequency of cell aberrations was studied for the first time using a micronucleus test in human buccal epithelium. Results were obtained of in vivo studies of wort samples to identify possible negative effects of hops, which contribute to an increase in extractive components in the finished drink during dry hopping and contain a large number of biologically active compounds (bitter and phenolic substances, essential oils), on the human body. The frequency of nucleus abnormalities in human buccal epithelium cells of persons using hoped and unhopped must samples was analyzed for the frequency of cellular abnormalities in human buccal epithelium. The following types of disorders were found: cells with micronuclei, two nuclei, notches, perinuclear vacuoles, "tongue" and "broken egg" type protrusions, karyopyknosis, karyolisis and karyorexis. Based on the data obtained, indices of repair and accumulation of cytogenetic disorders were calculated. No effect of hops on the reparation index and the index of accumulation of cytogenetic disorders was revealed. Factor analysis methods show that the main contribution to the variance of the trait system will be made by the factor "specificity of the cytogenetic indices under study".

STUDY OF THE INFLUENCE OF A HIGHER HOPPING DEGREE OF WORT ON THE FUNCTIONAL PROPERTIES OF ALE BEER

Experiments have been conducted to determine the effect of a higher hopping degree of wort (120 mg/l and 200 mg/l bitter α-acids) on the antioxidant capacity of ale beer. In one of the experimental variants, dry hopping with aromatic hop pellets (3 g/l) was applied. The higher hopping degree of wort did not lead to disturbance in the fermentation process. For beers containing 200 mg/l α-acids, the most significant was the increase in flavonoids (20.6-23.8%) compared to the variant with 120 mg/l α-acids. The polyphenols in highly hopped beer were increased by 6.6-7.1% compared to moderately hopped beer. The content of anthocyanins was not significantly affected by the addition of more hops. Antioxidant activity, expressed as equivalent vitamin C mmol/l, showed an increase of 4-5.2% for highly hopped beers compared to the control variant; when calculated relative to vitamin E, the increase was 5.8-7.5%. All beers were light, with excellent clarity and enhanced hop aroma.

Colour analysing of IPA brewing phases, including daily measuring of the fermentation process

Over the last decade, the brewing revolution has shown a new face to brewing. Besides the large-scale production, small-scale, artisanal hand crafted, and home breweries have also become important and relevant. This change has forced large-scale companies to change their usual methods and brew other types of recipes as well.One of the most popular ALE-type beers is the Indian Pale Ale (IPA), which gives beer a fruity-citrus flavour due to its hop content. It is especially popular with novice brewers as it has no enormous machine requirements compared to LAGER-type beers.In the study, we made our already known and popular recipe, a New England IPA, in a 30-litre brewing pot. This type requires only one type of malt; however, we added barley flakes, oat flakes, and wheat flakes to enhance the flavour. Hops are very dominant in the taste of this type of beer, five of which were used during brewing and later at “dry hopping” during fermentation.Sampling was performed every minute during mashing, brewing, hopping, cooling, and yeasting with a calibrated NIX-type measuring device with repetition to avoid measurement errors. During the fermentation stage, the colour change was observed by daily sampling. The study aims to separate the stages of brewing by colour and identify the stages of the already known biological and chemical activities by colour. This study is the first part of a more extended series of experiments where we will perform similar experiments on several types of beer (LAGER, STOUT, APA, WHEAT, RED, etc.). We would also like to know about the possible effect of carbonisation on colour, the possible effect of storage in a bottle on colour, and possible deviations from a similar decoction.

Effect of Czech Hop Varieties on Aroma of Dry-Hopped Lager Beer.

The hoppy aroma in beer is characterized by an overall pleasant profile. The impacts of five Czech hop cultivars, Rubin, Saaz, Vital, Harmonie, and Kazbek, were tested on the hop aroma of the resulting beers, compared with a control beer sample, which was hopped with a commercial hop extract during wort boiling. GC-MS analysis was used for the identification and quantification of aroma-active compounds in the hops and beer. Dry hopping was successful in terms of improving the hoppy aroma in beer. Odorants such as β-myrcene, linalool, geraniol, β-citronellol, humulene epoxide I, and 2-methylbutyl-2-methylpropanoate were found at higher concentrations than the control in all dry-hopped beers. To quantify the success of dry hopping, the transfer rates of hop odorants were calculated. Those of linalool, geraniol and humulene epoxide I were adequate, whereas the transfer rates of polar compounds, e.g., β-myrcene, were relatively low, mostly due to their polarity. Changes in hop oil constituents were clearly notable, with the generation of β-citronellol, the release of other terpene alcohols from their glycosides or oxidation of α-humulene. Yeast metabolism also played an important role in these changes.

Pilot brewery tests of Czech flavour hop varieties registered in 2022

Seven new Czech “flavour hop” varieties were tested in pilot brewing trials (50 l), in which samples of Ale-style beer were prepared using dry hopping. Essential oils in the beer were determined by fluidized-bed extraction combined with gas chromatography–mass spectrometry. Hop-derived aromas in beer were evaluated by descriptive method. Comparison of terpene essential oils in samples showed differences between hop genotypes and only a partial relationship with the sensory profile of beer. A cluster analysis of hop aromas in beer revealed the relationship between the pairs of Saturn and Pluto; N and Eris; Ceres and Jupiter hop varieties. The submitted results present the sensory properties of these new varieties and are useful for further study of the relationship between chemical and sensory profile of dry hopped beers.

Effect of dry hopping on the oxidative stability of beer

Electron spin resonance (ESR) spectroscopy was used todeterminethe effect of dry hopping on the oxidative stability and antioxidative potential of beer.Commercial beerwasdry-hopped at 5 °C and 20 °Cwith six hop varieties (Polish and American). The rate of radical formation and lag time were found to depend on the variety of hop used. An increase in the lag time and a decrease in the rate of radical formation occurred when dry-hopping was performed at 20 °C for all hop varieties (at 5 °C in some varieties). The lag time had a strong correlation with the TPC (total polyphenols content) in beer. The rate of radical formation was correlated with the iron content of the beer. A decrease in iron concentration was observed after dry-hopping at 20 °C. Overall, the evaluation of free radical formation using ESR is useful for predicting oxidative changes in beer during storage.

Impact of Hop Freshness on Dry Hopped Beer Quality

The hop plant is seasonal, but beer production continues throughout the whole year. The quality of hops begins to decrease immediately after harvesting; therefore, maintaining the highest possible quality is important. A good indicator of hop freshness is the hop storage index (HSI). In this study, three different varieties of hops with five different HSI values, from 0.3 to 0.7, were used for brewing with the dry hopping technique. The main goal was to evaluate the impact of the HSI value on beer quality in terms of hop aroma and bitterness. Alpha acids, iso-alpha acids, humulinones, bitterness units and hop aroma compounds were chemically analysed. Sensorial analysis was also conducted on all samples. Decreases in the intensity and quality of hop aroma were detected with increasing HSI. The quality of bitterness was also reduced. High HSI also led to undesirable gushing. Beers brewed with hops with HSI values greater than 0.4 had deviations in aroma and bitterness when compared with beers brewed with fresh hops.

The Effect of Dry Hopping Efficiency on β-Myrcene Dissolution into Beer.

The production of heavily hopped beers, such as Indian Pale Ale (IPA) styles, has been gaining momentum in recent years in the Central European markets. To this end, the dry hopping process is becoming increasingly popular, mostly in microbreweries, but also with larger manufacturers. In our research, we investigated the dissolution rate of the main volatile component of hops, β-myrcene with a modified dry hopping method. Following the primary fermentation, we applied the dry hopping process, where the weighed hops were chopped and blended into a container with 0.5 L of beer and later added to the young beer. During the dry hopping process, we determined various important parameters of the beer, and we repeated the same measurements for the bottled beer. In the first 96 h of the dry hopping process, we monitored the concentration of β-myrcene so that we managed to determine the dissolution rate constant (k = 0.1946 h−1). The β-myrcene concentration stabilizes after 44 h in the fermenter. At the same time, measurements were conducted for bitterness, pH, CO2 and alcohol content, extract and density during the process. Our experiment demonstrates that a new method of dry hopping provides a much higher concentration of β-myrcene (215 μg/L) than other methods indicated in former studies in the field. A health and safety assessment of β-myrcene was also made and we determined what the safe amount of β-myrcene ingested with IPA beer is. Our modified process was successful, we were able to determine the dissolution rate of β-myrcene, and the recommended daily intake of IPA beer with particular reference to β-myrcene.

Why Catechin and Epicatechin from Early Hopping Impact the Color of Aged Dry-Hopped Beers while Flavan-3-ol Oligomers from Late and Dry Hopping Increase Colloidal Instability

Dry hopping imparts distinct aromas but also a series of non-volatile compounds suspected of causing flavor and physical instability during beer storage. In this work, color, chill haze, total polyphenols, total flavanoids, and flavan-3-ol monomers (catechin and epicatechin) and oligomers (procyanidin dimers and trimers) were monitored in five commercial pale-colored Belgian dry-hopped beers over 24 months of storage at 20 °C in the dark. Fresh dry-hopped beers contained unusually high levels of flavan-3-ol monomers (up to 6.6 mg/L) and oligomers (up to 14.1 and 10.2 mg/L dimers and trimers, respectively). The increase in color intensity during storage (up to 6.4°EBC) correlated with fresh beer monomer levels, while the oligomer content correlated with chill haze formation (up to 25.7°EBC). The evolution of these two physical attributes also correlated with the level of total polyphenols in the fresh beers. In a pilot-scale production, kettle hopping was shown to impart either monomers (early) or oligomers (late), while dry hopping promoted efficient extraction of both monomers and dimers (extraction yields of 62 and 74%, respectively). Dry hopping thus plays an important role in color and chill haze increase.

The Influence of Hop Phenolic Compounds on Dry Hopping Beer Quality.

Background: The article considers the phenolic hop compounds’ effect on the quality indicators of finished beer. The topic under consideration is relevant since it touches on the beer matrix colloidal stability when compounds with potential destabilizing activity are introduced into it from the outside. Methods: The industrial beer samples’ quality was assessed by industry-accepted methods and using instrumental analysis methods (high-performance liquid chromatography methods—HPLC). The obtained statistical data were processed by the Statistics program (Microsoft Corporation, Redmond, WA, USA, 2006). Results: The study made it possible to make assumptions about the functional dependence of the iso-α-bitter resins and isoxanthohumol content in beer samples. Mathematical analysis indicate interactions between protein molecules and different malted grain and hop compounds are involved in beer structure, in contrast to dry hopped beer, where iso-a-bitter resins, protein, and coloring compounds were significant, with a lower coefficient of determination. The main role of rutin in the descriptor hop bitterness has been established in kettle beer hopping technology, and catechin in dry beer hopping technology, respectively. The important role of soluble nitrogen and β-glucan dextrins in the perception of sensory descriptors of various technologies’ beers, as well as phenolic compounds in relation to the formation of bitterness and astringency of beer of classical technology and cold hopping, has been shown. Conclusions: The obtained mathematical relationships allow predicting the resulting beer quality and also make it possible to create the desired flavor profiles.

Advances in dry hopping for industrial brewing: a review

highly hopped and dry hopped beer production and consumption has increased steadily for the last twenty years, following the rise of craft breweries in the United States of America and the trend they set over the world. This overuse of hops offers some environmental, technological, and economic challenges for the beer industry. Researchers have been studying several ways to make beer more ecofriendly by promoting reuse of spent hops and increasing extraction yields. Dry hopping is a size-dependent process, making it feasible for craft breweries with their small scale production, but quite a challenge for larger tanks and breweries. Based on the literature and industrial experience from brewers, the aim of this research was to analyze and discuss different dry hopping methodologies for the brewing industry and how the parameters affect the final product. In order to shed light on this trending topic and to better aid brewers in choosing the most suitable, efficient, and environmental-friendly dry hopping process for their brewery, this work approaches the main variables that promote aroma transfer from hops into beer and how to optimize it.

Aroma Profiles of Dry-Hopped Ciders Produced with Citra, Galaxy, and Mosaic Hops

Cider quality and consumer acceptance are greatly influenced by its aroma. With the continued expansion of the craft cider industry, cider producers are employing techniques such as dry hopping to develop unique flavor profiles. Few studies, however, have explored the VOCs of dry-hopped cider. Herein, we monitor the development of VOCs from pressed apple juice, through fermentation and dry hopping by HS–SPME–GC–MS, to elucidate when and how aroma compounds arise in cider production. In all, 89 VOCs were detected, spanning eight classes of organic compounds. Racking events decreased ester concentrations by 10 ± 1%, but resting on the lees allowed these pleasant, fruity aromas to be reestablished. Dry hopping was conducted with three types of hops (Citra, Galaxy, and Mosaic). The varied development of terpenes and esters between hop varieties supports the use of this technique to diversify the aroma profiles of ciders. Herein, we report that both the variety of hops and the timing of key processing steps including racking and hop addition significantly alter the identity and concentration of aroma-important VOCs in dry-hopped cider.

Evaluation of Czech hop varieties in beer

New hop varieties were evaluated in brewing tests in the years 2020 and 2021. The Saaz Comfort, Saaz Shine, Saaz Late and Saaz fine aroma hops were compared in lager style beers. Saaz Comfort has the best evaluation in terms of overall popularity. With a 95% probability, its evaluation is different from that of Saaz Shine. Saaz Comfort has a considerably different evaluation of bitterness than Saaz Late and Saaz Shine. The results show that fine aroma hop varieties have different characteristics and thus do not compete with each other. Kazbek and Cascade were compared in lager and ale beer styles. No significant difference was determined in the lager style. However, a significant difference between Kazbek and Cascade was established in ALE. Gaia has a considerably better evaluation in the lager style than in ALE. Gaia has the best evaluation of aroma and bitterness in lagers with dry hopping.