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Volatile components of aroma hops (Humulus lupulus L.) commonly used in beer brewing
Abstract
The essential oils from seven different aroma (finishing) varieties of hops (Humulus lupulus L.
... In addition to bitterness, hops provide specific aromas, spiciness, and a subtle hop flavour to beer, which is attributed to aromatic substances found in hop resins and hop essential oils (HEO), synthesized in lupulin glands during hop cone formation and ripening (Afonso et al., 2021). The diverse composition of HEO imparts individual taste characteristics and aroma properties to beer, encompassing notes of citrus, floral, fruity, spicy, woody, herbal, and grassy fragrances (Carbone et al., 2021;Lamberti et al., 2021;Nance et al., 2011). Investigating the composition of bitter compounds and essential oils in hops is crucial for advancing brewing techniques, particularly in the context of craft brewing, where unique aroma and flavour profiles are actively pursued (Humia et al., 2019;Machado et al., 2019;Donadini et al., 2017). ...
... European hop varieties, on the other hand, exhibit lower myrcene content, falling within the 20% to 40% range (Nesvadba et al., 2021). Myrcene contributes to a range of aroma properties, often described as green and hoppy with hints of pine and citrus, influencing modern brewing techniques like "dry hopping" (Hauser et al., 2019;Rettberg et al., 2018;Nance et al., 2011). Figure 4 displays the content and variability of myrcene in Ukrainian hop varieties studied. ...
... Caryophyllene, known for its woody, peppery, spicy, and earthy aromas, differs from humulene in taste and aroma characteristics (Rutnik et al., 2022a;Carbone et al., 2021;Rettberg et al., 2018;Nance et al., 2011). Caryophyllene is less prominent in European hop varieties but is found in English and American varieties such as Golding, Northdown, and Mount Hood (Ting et al., 2017). ...
The aim of the study was to evaluate the variation in essential oil content and composition within nine distinct Ukrainian hop varieties, with a particular focus on their genetic stability and suitability for brewing applications over 11 years of their cultivation. The hydrodistillation method (Analytica-EBC 7.10) was used to evaluate hop essential oil content and gas-liquid capillary chromatography (Analytica-EBC 7.12) to discern its qualitative composition. Variability was evaluated using statistical parameters. The essential oil content across the studied varieties spanned from 0.51 to 2.58 ml/100 g of dry hop cones. The highest content was measured in the bitter-aroma variety with a special aroma – Ruslan. The predominant essential oil components, including myrcene, caryophyllene, humulene, and farnesene, collectively constituted 70.0–84.2% of the total amount. The aroma varieties displayed myrcene content typical for European varieties (with the level up to 56.2% in the Ruslan variety). Farnesene content exhibited significant variation ranging from 0.3 to 17.6% with the highest content in Saaz-type varieties (Klon 18, Zlato Polissya, and National) and the bitter type Promin variety. Humulene content ranged from 13.2 to 32.6%. Among all studied varieties, Alta displayed the least variability for all parameters evaluated (Cv = 15.2%). This study underscores the genetic basis of essential oil composition in hops, emphasizing its potential as a biochemical criterion for identifying hop breeding varieties. The study revealed, that despite annual fluctuations, the essential oil content and composition remained within passport data declared for the variety. The findings provide valuable insight into a sustainable cultivation and optimal utilization of hops in the brewing industry.
... The ranges reported for these two varieties in the main producing regions [3,21,23,24,31,32]. ...
... Also, two other typical markers of Nugget variety were found, although in minimal amounts (nonan-2-ol and methyl dodeca-3,6-dienoate) (Supplementary Table 3, see page 102). Patagonian Nugget cones showed a higher proportion of sesquiterpenes when compared to Cascade, which may provide more intense earthy and spicy notes [31,34,35]. ...
... As for Cascade, this aromatic variety widely distributed has been repeatedly analysed regarding its brewing aromatic potential [31,34,36,37]. Also, new evidence is arising on the effect of the different terroirs on its aromatic and biochemical profile [25,38]. ...
The yields and chemical compositions of the resinous and essential oil fractions vary in different hop (Humulus lupulus L.) varieties and in different environmental conditions. South American hop crops with most of the production located in North Patagonia (Argentina), have not been thoroughly described. The two main varieties grown in this location are Cascade, widely used for aroma purposes and Nugget, a high alpha variety. To characterize the Patagonian hop products, the essential oils and resinous components of dried hop cones and pellets were analyzed. Both cones and pellets showed low HSI values indicating "freshness" of the samples. Argentinian Cascade alpha-acid levels and the ratio of alpha to beta acids (α/β), were above or in the upper range of Cascade typical values. For Patagonian Nugget, α-and β-acid values, as well as the α/β ratio, were within the range reported for other producing regions. As expected, essential oil yields were higher for the Nugget variety compared to Cascade (1.9 % and 1.0 % respectively); with both varieties high in myrcene (> 50 %). The α-humulene to β-caryophyllene (H/C) ratio values were typical for these varieties as well as the amounts of the main essential oil components, including a high proportion of (E)-β-farnesene in Cascade. Geraniol, nevertheless, was found in low amounts in Cascade; though two of its esters were present. This work indicates that hop varieties Cascade and Nugget appear well adapted to Patagonian growing and production conditions, producing high quality hop products. Future experiments to unveil the impact of the observed differences are of interest; including sensory analysis of beers hopped with the Patagonian terroir varieties compared with those from high producing regions.
... Overall, the panel could only perceive low intensities of 'crushed grass, sap', 'pine wood', and 'orange citrus fruit' aromas in the sesquiterpene fraction. This is in agreement with the literature, although so far, rather general sensory terms have been used to describe the aromas of sesquiterpene hydrocarbons such as 'green' (30), 'herbal', 'woody', 'earthy', and 'citrusy' (31,32). Precise terms were used in this study to highlight different sensory potentials among the hop oil fractions and the total hop oil and to facilitate conclusions about cause-effect relationships between volatile compounds and sensory characteristics. ...
... The ester fraction mainly comprised of geranyl isobutyrate [49], methyl 4-decenoate [31], and methyl geranate [33] as well as αhumulene [42] (also contained in the ketone fraction). The αhumulene [42] might have contributed to the 'crushed grass, sap' and 'pine wood' aroma background notes in the two fractions (33,49). ...
... methyl esters). Methyl 4-decenoate [31], methyl geranate [33] as well as other methyl esters such as methyl 4,8-decadienoate [32] are frequently identified in different hop varieties (54)(55)(56), however, their contribution to sensory profiles of the hop volatile mixtures has not yet been specified. ...
Hop oil fractions with unique sensory characteristics can be extracted from hop essential oil using green solvents such as supercritical (sc) CO2. These extracts meet clean label requirements and can be used to manage fluctuations in volatile composition caused by global warming. A sensory descriptive analysis approach was applied to assess the sensory profiles of Magnum hop oil and five scCO2 fractions. Ten sensory panellists were trained and used to establish an attribute lexicon. All samples, a control, and an experimental replicate were evaluated at 800 μg/L in ethanol (4% abv) in triplicate. Data were analysed by three‐factor Analysis of Variance (ANOVA) and Tukey's test (HSD). Volatile compounds were determined using gas chromatography‐mass spectrometry (GC‐MS). Relationships between the volatile compounds and sensory profiles were analysed using Principal Component Analysis (PCA) and Partial Least Squares (PLS) regression. In contrast to the majority of fractions, the total oil (the most complex sample) and the sesquiterpene fraction (as the largest chemical group in the total oil) were not described by any key sensory attributes. This illustrates the advantage of hop oil fractionation to pull out specific sensory characteristics. The β ‐myrcene in the myrcene fraction induced an intense ‘crushed grass, sap’ aroma while the fractions containing several geranyl and methyl esters and ketones were characterised by fruity‐ and floral‐type aroma and flavour attributes. Interestingly, the most polar fraction comprising of terpene alcohols delivered a complex sensory experience by adding sweetness. Moreover, a trigeminal ‘peppery tingling’ sensation was detected, which is likely to be caused by sensory interactions. © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling
... Its name descends from the Cascade mountain range, extending through Washington and Oregon States. The popularity of the Cascade hop, especially in the USA craft brewery industry, is mainly due to the combination of high production yield, resistance to downy mildew infections (Moir 2000) and to the characteristic floral, fruity, particularly citrusy, aroma with little earthy or spicy notes (Kishimoto et al. 2006;Nance and Setzer 2011). ...
... Cascade. The essential oil (EO) composition was analysed by GC-O, GCxGC (Eyres et al. 2007;Steinhaus et al. 2007) and GC-MS (Nance and Setzer 2011;Mongelli et al. 2016). Nance and Setzer (2011) identified myrcene, a-humulene, (E)-caryophyllene and (E)b-farnesene as the EO main components. ...
... The essential oil (EO) composition was analysed by GC-O, GCxGC (Eyres et al. 2007;Steinhaus et al. 2007) and GC-MS (Nance and Setzer 2011;Mongelli et al. 2016). Nance and Setzer (2011) identified myrcene, a-humulene, (E)-caryophyllene and (E)b-farnesene as the EO main components. ...
Several aroma hops (Humulus lupulus L.) were recently introduced in Northern Italy as a small-scale production of excellence. In this preliminary study, the American cultivar Cascade was investigated in a combined morphological and phytochemical survey. Morphological investigation on trichome structure, density and distribution was performed by scanning electron microscopy and light microscopy. Essential oil composition, α/β-acid and polyphenol profiles over 3 years were determined by GC-MS and HPLC analyses. Two types of non-glandular (simple and cystolithic) and glandular (peltate and bulbous) trichomes were observed on leaves and female inflorescences. The peltate trichomes resulted as the main sites of terpene production and accumulation. The essential oil profiles showed myrcene, β-caryophyllene, (E)-β-farnesene and humulene epoxide II as the dominant compounds over the three collection times, although with different relative abundances. The presence of two exclusive compounds, γ-muurolene and trans-γ-cadinene, characterized the investigated cv. Cascade, potentially enhancing herbal, woody and spicy aroma traits of this cultivation in Northern Italy. The bitter acid composition showed quantitative values consistent with literature data only for the second and third monitoring year. Qualitative differences in polyphenol content were also recorded, for the presence of quercetin-3-O-malonylglucoside and kaempferol-3-O-rutinoside, which may characterize this peculiar Italian cultivation.
... A similar comparison of hop oil composition for seven different hop cultivars of European and North American types based on GC/mass spectrometry (MS) results is given in reference [27]. Neither reference [29] nor [30] used phytochemical standards of the hop oil components for quantification purposes and the contents of individual components were comparatively assessed against the FID-derived total sum of peak areas [29] or the MS-derived total ion current [30]. To our best knowledge, so far, quantification of the components of different commercially available hop oils has not been performed based on chemical or phytochemical standards, except for sporadic cases (such as the use of isobutyric, 2-methylisobutyric, and isovaleric esters, as reported in reference [24]). ...
... A similar comparison of hop oil composition for seven different hop cultivars of European and North American types based on GC/mass spectrometry (MS) results is given in reference [27]. Neither reference [29] nor [30] used phytochemical standards of the hop oil components for quantification purposes and the contents of individual components were comparatively assessed against the FID-derived total sum of peak areas [29] or the MS-derived total ion current [30]. To our best knowledge, so far, quantification of the components of different commercially available hop oils has not been performed based on chemical or phytochemical standards, except for sporadic cases (such as the use of isobutyric, 2-methylisobutyric, and isovaleric esters, as reported in reference [24]). ...
Seven commercial hop (Humulus lupulus L.) oils originating from a selection of North American hop varieties (Amarillo, Azacca, Cascade, Centennial, Chinook, Saaz, and Ahhhroma) and six homemade hop oils hydrodistilled from the same commercial hop pellets (except Ahhhroma) were compared. Seven terpenes regarded as hop oil markers (i.e., α-pinene, β-pinene, β-myrcene, β-ocimene, limonene, β-caryophyllene, and α-humulene) and methyl heptanoate were identified and quantified by GC–MS and GC-FID. The antioxidant potential of the commercial hop oil samples was evaluated using electron paramagnetic resonance (EPR) spectroscopy, while their components’ antibacterial (against Aliivibrio fischeri) and enzyme (α-glucosidase and lipase) inhibition activities were screened using high-performance thin-layer chromatography (HPTLC)-based assays. A distinct feature of five of the commercial hop oils (except Saaz and Ahhhroma) was relatively high contents of β-myrcene (between 4.21 and 6.40 µg mg−1 hop oil). Azacca, Cascade, and Centennial hydrodistilled oils had perceptibly higher contents of β-caryophyllene than the rest, and most of them (except Chinook) contained relatively high amounts of α-humulene. Differences between the terpene profiles of the commercial and homemade hydrodistilled hop oils suggested that the commercial hop oils were derived from hop cones in a process different from hydrodistillation. The oils showed relatively low antioxidant potential, comparable to that of popular beers and white wines. The highest antioxidant potential was observed in Ahhhroma oil, while it was very low in Centennial oil, and no antioxidant potential was observed in Cascade and Saaz oils. The developed streamlined workflow, including parallel HPTLC-directed bioassays and HPTLC—TLC–MS Interface—SPME–GC–MS, enabled the identification of β-myrcene, dimyrcenes, β-farnesene, and 2-methylbutyl isobutyrate as anti-obesity compounds and β-farnesene, β-myrcene, and 2-methylbutyl isobutyrate as weak antibacterial hop oil components.
... On the other hand, the qualitative differences were significant. In fact, the number of compounds detected in Chinook (31) was significantly higher than that in Cascade (18). In particular, compounds such as, α-pinene, terpinolene, p-cymen-8-ol, 4decenoic acid, methyl ester, Z-, α-selinene, γ-cadinene and selina-3,7(11)-diene, ranging between 1.1 and 4.6%, were present only in Chinook and were missing in Cascade, in addition to other minor compounds with relative percentages lower than 1.0%. ...
... A somewhat more conspicuous number of papers discuss the chemical composition of essential oils (EOs) obtained from different hop cultivars [17][18][19]. Particular attention has been paid to EOs obtained from Cascade whose cultivation is constantly expanding, especially in Italy. Rodolfi et al. [20] characterized the EOs from Cascade hops grown in nine Italian regions, demonstrating how the cultivation area has a substantial effect on plant growth as well as crop years [21] by influencing their secondary metabolism. ...
Hop (Humulus lupulus L.) is grown mainly for the production of beer. The flowers of the female plant give it the bitter taste and pungent aroma. There are a large number of hop varieties differing in their α-acid content, essential oil levels and odor profiles. Aside from their use in brewing, more recently, hops have been used for the pharmacological properties of its derivatives that are of great importance to the pharmaceutical industry. Hop is known to have a fairly complex chemistry characterized by the presence of a variety of sesquiterpenoids, diterpenoids and triterpenoids, phytoestrogens and flavonoids. Additionally, considering the countless applications in the pharmacological sector in recent years, a chemical characterization of the different cultivars is essential to better identify the source of specific secondary metabolites. For this purpose, the dried inflorescences of two hop cultivars, Chinook and Cascade, were investigated using Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry and Liquid Chromatography-Tandem Mass Spectrometry (SPME-GC-MS and LC-MS-MS) to describe their metabolomic and proteomic profile. Furthermore, thanks to an in-depth statistical survey, it was possible to carry out a comparative study highlighting interesting implications deriving from this investigative study.
... To assess the volatile composition of the hop samples, the hydrodistilled hop essential oil was analyzed for 24 different terpene and terpenoid compounds with quantitation achieved via GC-FID. Although other hop essential oil constituents such as thiols also play an important role in the hop aroma, these terpenes and terpenoids are known to significantly contribute to the hop aroma and the aroma of dry-hopped beers, [2,[40][41][42][43][44] especially in the case of the two hop varieties investigated in this study. A Kruskal-Wallis Test was applied for each quantitated hop oil compound to identify significant differences between the four sample groups (by state of origin and variety). ...
... The remaining ten attributes in order of decreasing frequency were resinous, sweaty, citrus, tropical, herbal, grassy, vegetal, woody, floral, and fruity. These observations were well in line with recent studies reporting the aroma of Cascade hops as resinous, citrus, tropical, herbal, and fruity (grown in Washington, Oregon, and Idaho) [3] ; as fruity, floral, citrus, and herbal (grown in Washington) [9] ; as citrus, herbal, woody, floral, and fruity (grown in Washington) [43] ; as well as grassy, citrus, and floral (grown in Oregon and Canada). [8] Compared to Amarillo, Citra, Hallertau Blanc, Sorachi Ace, and Saaz hops, the aroma of Cascade hops grown in Washington has been described as especially floral with a moderate citrus note, potentially as the result of high amounts of geraniol and linalool. ...
The impact of the growing environment on the aroma of agricultural products such as wine, coffee, or tea has been investigated in detail, leading to the concept of regional identity; however, there have been only limited studies examining regional variation in hops. A systematic investigation of Cascade and Mosaic® hops from the 2020 harvest year grown at 39 different locations in Oregon and Washington was performed using chemical/instrumental and human sensory analyses, which revealed significant between-state and within-state differences for both varieties, suggesting substantial regional and subregional identity effects. A subset of 14 hop samples was selected to produce standardized single-hop beers (IPA) in pilot scale. Sensory evaluation of the beers revealed similar regional-dependent results as observed for the hops with slightly stronger fruity, citrus, and tropical notes but weaker herbal, grassy, and woody notes in the beers compared to hops, suggesting that the regional identity effect was observable in beer.
... τ-Cadinol was present in the tested oils at the following levels: 6.83% "F1", 9.64% "F2", 10.65% "K", 24.25% "W", 28.06% "H". Other authors also confirmed the diversity of composition between different hop oils, which results from the varietal characteristics and is also shaped by cultivation and technological factors (Nance and Setzer, 2011;Vázquez-Araújo et al., 2013). The hop oil fraction is a complex mixture of volatile aromatic compounds, which are considered essential, because they give hops their characteristic smell (Olšovská et al., 2016). ...
... Jirovetz et al. (2006) reported that the main components of the volatile fraction of hops from the region of Bavaria were myrcene (45.3%) α-humulene (31.2%) and β-caryophyllene (9.8%). Similarly the main components in hops from California were confirmed by Nance and Setzer (2011), identifying a total of 98 volatile compounds. Mockute et al. (2008) identified 120 components in hop oil from plant material harvested in east Lithuania. ...
Purpose
Hop cones are valuable raw materials in the brewing industry, as well as in medicine. The aim of the study was to determine the content of selected groups of phytochemical constituents in the pharmaceutical grade herbs of hop cones Humulus lupulus L. and to examine the antioxidant activity of the essential oil (EOHl). In addition, molecular docking was performed to elucidated interactions of different hops cones components with the main enzymes involved in diabetes type II and hypertension.
Methods
Total flavonoids and phenolic contents are spectrophotometrically determined. The content EOHl was determined by hydrodistillation. Volatile compounds were identified by GC-FID and GC-MS. Antioxidant effectiveness of EOHl is examined by DPPH radical scavenging method. Docking study was performed using Molecular Operating Environment software (MOE).
Result and conclusion
The tested hop cones contained up to about 4.20% of total phenolic compounds and up to about 0.37% flavonoids. The content of EOHl reached up to 0.495% v/w with τ-cadinol and α–humulene as the main ingredients. In addition, EOHl contained up to 4.87 mg/ml polyphenolic compounds. The radical-scavenging activity of EOHl ranged from 25.31 mM to 66.99 mM expressed as Trolox equivalents. Docking simulations showed that the most probable potent inhibitors of dipeptidyl peptidase-4, alpha-amylase, alpha-glucosidase, and angiotensin converting enzyme (ACE) were rutin and astragalin with high energy score compared to the reference ligand. From the results obtained it could be predicted that anti-diabetic and antihypertensive potential of hopes cones could be attributed to the presence of rutin and astragalin.
... Several previously published papers Nance, & Setzer, 2011;Inui et al., 2013) have identified the key aroma compound groups of hops that highly contribute to hoppy beer flavor, including terpenes and terpenoids. The qualitative and quantitative compositions of terpenes and terpenoids determine the aroma differences among hops varieties. ...
... A time-efficient and accurate modeling method, as well as objective aroma representation, should be investigated in this study. Moreover, to date, it is evident from previous studies Nance, & Setzer, 2011;Inui et al., 2013), key aroma compound, β-myrcene, α-humulene, β-caryophyllene, linalool and geraniol, that highly contribute to hoppy beer flavor were identified. Obviously, the characteristic aromas of proprietary hops are influenced by their unique chemical combinations of compounds, especially the highly impact aroma compounds. ...
In recent years, proprietary hops (Citra, Simcoe, and Mosaic) become the most sought-after hops among brewers due to their excellent aroma. However, they are restricted to the owners unless other growers purchase the costly licensing agreements. Many public hops are available to the growers without any additional costs, but their aroma is difficult to match to the proprietary hops. Although proprietary and public hop varieties are unique in their aroma profiles, all hops varieties contain similar volatile compounds, merely differ in the quantity of different individual compounds. The main objective of this thesis was to investigate the feasibility of matching the aroma of proprietary hops by blending a number of public hops. The aroma profiles of hops were detected by flavor-detection methods including Gas chromatogram-flame ionization detector (GC-FID), Gas chromatography-mass spectrometry (GC-MS), Headspace solid-phase microextraction/gas chromatogram–mass spectrometry (HS-SPME/GC-MS), and sensory evaluation. The modeling was achieved by applying a mathematical optimization technique – quadratic programming. For matching proprietary hop aroma, public hop pellets or hop oils were mixed with different percentages in models (e.g., proprietary hop A= x% public hop B + y% public hop C + z% public hop D). The aroma of Citra pellets was closely mimicked by 25.2 % Eureka, 33.2 % Centennial, and 36.7 % Triple Pearl. The aroma of Simcoe pellets was closely mimicked by 10.0 % Cascade, 50.0 % Us Goldings, 71.1 % Centennial, and 10.4 % Triple Pearl. The aroma of Mosaic pellets was closely mimicked by 6.5 % Eureka, 84.8 % Centennial, and 3.0 % Triple Pearl. In addition, it nearly mimicked the Citra oil with 35.2% Brewers Gold, 5.2 % Cashmere, 32 % Centennial, and 35.7 % Triple Pearl. The obtained aroma of models was validated in the beers with both the high similarity of aroma profiles (R2 > 0.90) and sensory evaluation. This research provided a novel idea on the application of mathematical optimization and flavor-detection technologies for modeling the aroma of hops. The success of this project can increase the usage of public hops and extend such an application to other flavor developments. Advisor: Changmou Xu
... Nance et al. [36] and Forteschi et al. [37] reported the same major chemical constituent identified in the present work, but they highlighted a predominance of monoterpenes as the main chemical class in the EOs obtained from Cascade hops. ...
... In particular, monoterpene hydrocarbons were the most abundant chemical class, as they accounted up for 71.6%, followed by sesquiterpene hydrocarbons, which represented 23.7% of the whole headspace composition. Among the former class, myrcene (64.9%) was the main detected chemical, whilst among the latter, α-humulene (12.0%), β-caryophyllene (6.6%) and (E)-β-farnesene (1.5%) were predominant, confirming what has been previously reported [36,37]. ...
The present work is an evaluation of the chemical composition of the aroma and the sensorial characters of a beer flavored with Hibiscus rosa-sinensis flowers. Moreover, the total polyphenol, flavonoid and anthocyanin contents and the antioxidant activity of the plant materials and beers were assessed. A comparison with a liqueur flavored with the same hibiscus flowers was also performed. Non-terpene derivatives constituted the main class of components of the aroma of both samples, representing 96.4% of the whole volatilome in the control beer and 99.0% in the hibiscus one. Among this class, esters were the most abundant compounds, being significantly higher in the treated sample (77.6%) than in the control (68.4%), followed by the alcohols (20.9% in control beer and 18.8% in hibiscus beer). From a sensorial point of view, the control beer was characterized by malty and hoppy notes, attributable to the noticeable content in myrcene and α-humulene in its headspace, while in the hibiscus beer, floral and fruity notes, typical of esters and alcohols, prevailed. The polyphenol content was significantly higher in the treated beer (143.96 mg/g) than in the control, as well as the total flavonoids and the total anthocyanins, and, consequently, the antioxidant activity (DPPH-assay).
... The variable depletion of terpenes in beers has been linked to its adsorption onto beer head and the yeast biomass. b-Myrcene, a-humulene and b-caryophyllene in this order constitute the greatest proportion of terpenes in Cascade hops (Nance & Setzer, 2011). In the wort, b-myrcene and a-humulene were similarly reflected as the main terpenes present though bcaryophyllene, on the contrary, was inherently absent but detected in all beers, significantly so in beers fermented with Prelude. ...
... In the wort, b-myrcene and a-humulene were similarly reflected as the main terpenes present though bcaryophyllene, on the contrary, was inherently absent but detected in all beers, significantly so in beers fermented with Prelude. The production of b-caryophyllene along with several other terpenes including afarnesene and cadalene may be associated with terpene biotransformation or b-glycosidase activity which catalyses the hydrolytic release of terpenes and other glycosidically bound volatiles (King & Dickinson, 2000;Nance & Setzer, 2011). ...
This work evaluated the potential of three commercial non‐Saccharomyces yeast strains Torulaspora delbrueckii (Biodiva and Prelude) and Lachancea thermotolerans (Concerto) for beer fermentation. The fermentation performance, volatile and non‐volatile profiles were compared. Growth behaviours of all three yeast strains exhibited similar trends during the initial fermentation phase although a marked population decline was detected in strains Prelude and Concerto, which also showed a rapid utilisation of maltose, while strain Biodiva was unable to consume maltose and consumed lesser amounts of amino acids. Additionally, terpenoids inherently absent in the wort such as β‐caryophyllene and geranyl acetone were produced in all beers, significantly higher in beers fermented with strain Prelude. For volatile profiles, Prelude and Concerto produced more ethanol and significantly higher amounts of acetate esters and long‐chained ethyl esters. Strain Biodiva, on the other hand, produced higher amounts of isoamyl alcohol and ethyl butanoate.
... The temperature which the H matrix was subjected to determined the volatilization of this compound. The concentration of limonene, in any case, is slightly lower than what can be seen in literature data [68,69]. In the class of sesquiterpene hydrocarbons, we found α-humulene (T0 25.12%; F 24.04%; H 25.61%; VRT 24.76%), β-caryophyllene (T0 10.11%; F 10.52%; H 11.17%; VRT 9.40%), (E)-β-farnesene (T0 6.93%; F 6.83%; H 7.43%; VRT 6.02%) and other compounds in lower concentrations ( Table 2). ...
Hop is a key ingredient in beer production, and drying it allows it to be stored before use. Unfortunately, postharvest drying techniques can negatively affect hop quality. In this study, we compared drying using a hot stove (H), freeze-drying (F), and ventilated at room temperature (VRT) drying, focusing on the chemical quality and essential oil composition. To achieve 80% water removal, F and H took two days, while VRT took five days. F and H preserved a high content of total chlorophyll (F 81.89 g/kg dm; H 82.70 g/kg dm) and carotenoids (F 54.02 g/kg dm; H 54.71 g/kg dm). The hop storage index (HSI) increased with all drying techniques, but especially in F and H. The lowest amount of polyphenols was found in the H sample (348.48 g/kg dm), while the highest content was found in VRT (631.11 g/kg dm). Freeze-drying gave the best results, especially in relation to the amount of polyphenols and antioxidant power of the product. Regarding essential oils, in the class of sesquiterpene hydrocarbons, we found α-humulene (F 24.0%; VRT 24.7%; H 25.6%), β-caryophyllene (F 10.5%; VRT 9.4%; H 11.1%), and β-farnesene (F 6.8%; VRT 6.0%; H 7.4%). The total monoterpene hydrocarbon amount increased in the VRT sample. Thus, freeze-drying emerges as an alternative technique to the hot stove; however, the cost is high. Instead, drying at ventilated room temperature represents a sustainable and valid technique for preserving the aromatic characteristics and polyphenols of the product.
... observed that Saaz hops lack some ester compounds with specific branchedchain structures. Nance and Setzer [23] analyzed Cascade and Saaz hop essential oils by GC-MS and found that isobutyl isobutyrate and isoamyl propionate were not present in Saaz essential oils. Forster and Gahr [24] showed that during brewing, 53-83% of these compounds were transferred, indicating their contribution to beer flavor. ...
Hops (Humulus lupulus L.) are a raw material for brewing beer, providing it with unique flavor and bitterness. In the present study, hops cultivated in Taiwan, the United States, and the Czech Republic were studied and extracted via steam distillation. The essential oils obtained were analyzed using headspace solid-phase microextraction (HS-SPME), direct injection combined with gas chromatography-flame ionization detector (GC-FID), and gas chromatography-mass spectrometry (GC-MS). The results showed that the essential oil yield of Hualien hops was 0.31%. A total of 143 and 162 volatile compounds were identified from seven types of hops using HS-SPME and direct injection, respectively. Sesquiterpenes were relatively more abundant in Taiwanese hops, and β-farnesene was identified in both Taiwanese and Cascade hops from the U.S. Additionally, dimethyl sulfide and dimethyl disulfide were identified in both the U.S. and the Czech Republic hops. Principal component analysis, based on their volatile compound profiles, showed that Taiwanese hops were the most similar to Saaz hops from the Czech Republic.
... The appearance of citrusy and floral aroma attributes coincided with the presence of β-myrcene, 3-carene, linalool, d-limonene, and geraniol in the kombucha samples supplemented with Cascade hops (Fig. 6 and Table 5). These findings align with previous reports, highlighting linalool, geraniol, and monoterpene hydrocarbons, particularly myrcene, as characteristic aroma compounds in Cascade hops (Nance and Setzer 2011;Lafontaine and Shellhammer 2018). Moreover, the addition of hop decreased the perception of acetic and tea-related flavor aromas, which can be considered undesirable flavor attributes in kombucha. ...
In recent years, there has been a surge in the production of kombucha—a functional beverage obtained via microbial fermentation of tea. However, fresh, unpasteurized kombucha is sensitive to quality deterioration as a result of, among other factors, oxidation. The addition of hops seems to be promising, due to their antioxidative properties, which may improve the stability of kombucha. However, aiming at retaining the highest antioxidative properties of kombucha, it remains unclear at which stage of the production process hops should be added. The study investigated the effect of hop supplementation during kombucha production on the basic physicochemical, antioxidative, and sensory properties of kombucha. Cascade hops in the concentrations 0.5 and 2 g/L were added at the onset of tea infusion and to the fresh, unpasteurized kombucha. The addition of hops (particularly at the pre-fermentation stage of production) led to a significant decrease in radical formation in the produced kombucha measured by electron spin resonance spectroscopy (ESR), which correlated with the higher DPPH antiradical activity and the elevated bitter α-acid content. From the sensory perspective, the post-fermentation addition of hops to kombucha resulted in a significantly higher rating of the overall quality. This enhancement was directly associated with heightened bitterness, increased presence of fruity and citrusy aromas, and a simultaneous reduction in the intensities of acetic and tea-related attributes. The data presented in this study are relevant for kombucha producers, who want to deliver a sensory-novel product in combination with an improved oxidative stability.
Key points
• Hop addition in kombucha production improves the antioxidative activity of the beverage.
• Hop α-acids display higher antioxidative properties in kombucha than polyphenols.
• Oxidative stability of kombucha fortified with hops depends on the timing of hops addition.
• Hop addition enriches the taste and aroma attributes of kombucha.
... The latter ingredient, hops (Humulus lupulus; Cannabaceae [5]), is known for its contribution to beer's organoleptic characteristics as well as its preservation. Several compounds are particularly valued in hops divided in two main groups: α-acids, β-acids, and phenolics which mainly contribute to its "bittering" potential [6] and the constituents of their volatile fractions (terpenoids) playing a major role in their "aromatic" expression. Added in the brewing process, during the hopping stage, H. lupulus significantly contributes to the organoleptic character of the final product. ...
Introduction
Determining the bittering profile of hops is a prerequisite for their use in beer making industry. To fully grasp the brewing potential of Corsican hops, it is therefore essential to perform a precise quantification of the molecules responsible for their bittering power.
Objective
The aim of this study is highlighting of the bittering profile of Corsican hops.
Methodology
A method for the characterization and quantification of α‐acids, β‐acids, and phenolic compounds in Corsican hops using high performance liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) has been developed. In addition to the six α‐ and β‐acids commonly quantified in hops, seven others hop acids were identified using a new methodology based on the analysis of their fragmentation pattern in full‐scan detection mode. The compounds were then quantified as humulone or lupulone equivalents. Subsequently, a metabolomic analysis of hop cones was conducted using the method of molecular networking.
Results
A total of 28 compounds were quantified. The influence of both annual climate variations and transplantation on the chemical composition of hops extractives was highlighted. The molecular network elucidation led to the identification of 34 compounds. Among them, eight were previously undescribed in hops, including one previously unknown to the literature.
Conclusion
The methodologies developed in this study have shed light on the “bittering” potential of Corsican hops which represents a significant economic opportunity for the local brewing industry potentially establishing a new, sustainable, and profitable hops market. This work focuses extensively on the phenolic compounds and the bittering acids of Corsican hops, aiming to highlight their unique organoleptic characteristics and the influence of the Corsican terroir on their chemical composition and abundance.
... The temperature at which the drying process is conducted inevitably determines the loss of chemical compounds present within the inflorescence . The quantity of essential oils presents in the fresh product can be reduced by 30-40% following processing, due to the extreme volatility of these compounds (Nance & Setzer, 2011;Rybka et al., 2018). For this reason, the temperature control which the process is carried out to, is of extreme importance with regard to the quality of the final beer production (Raut et al., 2020). ...
Drying techniques are important for hop storage and quality. The stage of hop addition in beer is another important issue. This study focuses the impact of two drying techniques [freeze-dryer (F) and hot-stove (H)] of Cascade hop, on the chemical, aromatic and sensory quality of beer, comparing beers produced without (BF and BH) and with dry-hopping technique (BFDH and BHDH). Dry-hopping with H significantly increased the bitterness index and reduced the titratable acidity. Isoamyl acetate (450.60 μg/L) and ethyl caprylate (313.60 μg/L) were in high content especially in BH while, ethyl-n-caproate (359.37 μg/L) had the highest content in BF. The beers made with dry-hopping technique, had a significantly higher content in terpenes especially in BFDH (1006.18 μg/L). Sensory evaluation indicated difference preferences, with freeze-dried hop beers generally favored. In conclusion, depending on the type of beer desired, hops dried in different way and a specific hopping technique can be chosen.
... Traditionally, hops are added one or more times during the boiling process (kettle hopping). Boiling permits the conversion of α-acids into iso-α-acids, which is why hops with greater bittering compounds tend to be used [19][20][21][22]. A second option is the late hopping technique, in which hopping is carried out at the end of the boil, limiting the conversion of α-acids while favouring the retention of volatile molecules. ...
This paper evaluates the effects of an alternative hopping technique, called dip hopping, on beer. This technique involves infusing hops in hot water (or in a portion of wort) and subsequently combining the infusion with the wort (after wort cooling) directly in the fermenter when the yeast is added for fermentation. The reference beers were produced employing the “traditional” late hopping technique, and the experimental beers were produced using the dip hopping technique. A variety of hops with a significant concentration of essential oil and a strain of yeast with high β-glucosidic activity capable of releasing aromatic molecules from precursors supplied by hops were used. The samples were analysed in terms of alcohol content, degree of attenuation, colour, and bitterness. Sensory analysis and gas chromatography analysis were also performed. The data showed statistically significant differences between the reference beers and the experimental beers, with the latter featuring greater hints of citrus, fruity, floral, and spicy aromas. As an overall effect, there was an increase in the olfactory and gustatory pleasantness of the beers produced with the dip hopping technique.
... The specific hop aroma emerges from its bitter acid content and many other compounds, including essential oils and polyphenols [4][5][6] . Changes in alpha bitter acids affect the quality of hops [7][8][9][10][11][12] , and there has been a recent change in consumer preference towards beer aromas and flavors that heavily depend on high-quality hops 13,14 . Amplified by the ongoing craft beer popularity 13 , this trend contrasts with previous demands for lower alpha content 14 . ...
A recent rise in the global brewery sector has increased the demand for high-quality, late summer hops. The effects of ongoing and predicted climate change on the yield and aroma of hops, however, remain largely unknown. Here, we combine meteorological measurements and model projections to assess the climate sensitivity of the yield, alpha content and cone development of European hops between 1970 and 2050 CE, when temperature increases by 1.4 °C and precipitation decreases by 24 mm. Accounting for almost 90% of all hop-growing regions, our results from Germany, the Czech Republic and Slovenia show that hop ripening started approximately 20 days earlier, production declined by almost 0.2 t/ha/year, and the alpha content decreased by circa 0.6% when comparing data before and after 1994 CE. A predicted decline in hop yield and alpha content of 4–18% and 20–31% by 2050 CE, respectively, calls for immediate adaptation measures to stabilize an ever-growing global sector.
... The most common method used to identify and quantify volatile components is gas chromatography coupled with mass spectrometry, which is used in this study. The three main components identified in hops' essential oils are usually myrcene, humulene, and caryophyllene [4][5][6][7][8][9]. These molecules and their abundance are, therefore, responsible for the development of the desired beer aroma during the process. ...
Essential oils from wild Corsican hops have never been described before. Following selective harvesting and extraction of plant material, chemical analysis was performed by GC–FID and GC–MS. Subsequent quantitative analysis demonstrated significant inter-stations variability due to pedoclimatic conditions. These singularities produce organoleptic differences, especially within Italian hops, which are the current benchmark for the Mediterranean hops’ population. Corsican wild hops are no exception. Accordingly, three olfactive bouquets were identified by a panel of selected and trained sensory analysts: woody herbaceous ginger notes, herbaceous citrus notes, and common notes. These bouquets appeared to be correlated to pedoclimatic parameters mentioned earlier such as altitude and proximity to the sea. A very rare and appreciated bouquet was associated with high levels of zingiberene in hops growing at moderate altitude and relatively far from the coastline. This study shows the importance of growing sites and pedoclimatic conditions to produce hops with the desired organoleptic notes during the beer making process and provides detailed identification of essential oils from Corsican wild hops.
... The most common terpenes found in all assays were geraniol, which gives a floral aroma (rose and geranium) to beer; citronellol (lemon, lime); and humulene. Humulene is the main terpene found in cascade hops and imparts a citrusy, floral, woody and earthy aroma to products [46,47]. Geranyl acetate and caryophyllene oxide were only detected at 0 h and were probably metabolized in all assays. ...
Kombucha is a beverage obtained from fermentation of Camellia sinensis tea using a symbiotic culture of bacteria and yeast (SCOBY). This association of bacteria and yeasts can be an interesting source of microorganisms for developing fermented beverages, including beer. The objective of this study was to evaluate kombucha SCOBY and commercial brewing yeast as a starter culture for the elaboration of beer. Three assays were performed to develop the beverage (C = control, KL = kombucha + yeast, K = kombucha). The pH, density, carbohydrates, organic acids and ethanol were evaluated during fermentation. Microbial counts (yeasts and mesophilic bacteria) and volatile compounds were recorded at the initial and final fermentation times. The content of total phenolic compounds, antioxidant capacity, color and bitterness (IBU) of the beers were determined. The results showed that kombucha-fermented wort produces a beer with differentiated characteristics. Increased lactic acid (0.73 g/L) and low alcohol content (1.3%) were observed in the K assay. Further, desired volatile compounds, such as ethyl octanoate, phenethyl acetate and 2-phenylethanol, were also found in this beer. The combination of kombucha and commercial yeast for beer production showed carbohydrate consumption and contents of organic acids similar to those of control beer, producing beers with an alcohol content of 5.9%. From the results, it was possible to observe a tendency for the content of total phenolic compounds (37.57, 33.00 and 31.64 mg/100 mL for K, KY and C assays, respectively) to increase when the wort was inoculated with kombucha. There was no difference in the antioxidant activity of the produced beers. All produced beers showed a yellowish color and a bitterness value (IBU) of 27%. The present study showed that adding kombucha as a starter culture produced beer with differentiated properties, such as high antioxidant activity, low alcohol content and sour characteristics.
... Overall, the panel could only perceive low intensities of "crushed grass, sap", "pine wood", and "orange citrus fruit" aromas in the sesquiterpene fraction. This is in agreement with the literature, although so far, rather general sensory terms have been used to describe the aromas of sesquiterpene hydrocarbons such as "green" , "herbal", "woody", "earthy", and "citrusy" (Nance & Setzer, 2011;Whittock & Koutoulis, 2010). Precise terms were used in this study to highlight different sensory potentials among the hop oil fractions and the total hop oil and to facilitate the drawing of conclusions about cause-effect relationships between volatile compounds and sensory characteristics. ...
Considering the substantial amount of research that has been published in the field of hop science during the last decades, very little is known with regard to the multimodal flavour perception of hop-derived volatiles that not only contribute to the pleasant ‘hoppy’ aroma and flavour, but are also involved in other sensations of gustatory and trigeminal origin perceived in beer. The aim of this research was to further understand the sensory complexity of Magnum hop essential oil and scCO2 hop oil fractions extracted therefrom. This PhD project combined static and dynamic sensory techniques, an established gas chromatographic method, and comprehensive statistical analyses to investigate the relationship between hop volatile compounds and their sensory characteristics (quantitative and qualitative) in different matrices. The olfactory, gustatory and trigeminal differences between five hop oil fractions representing the main chemical classes of Magnum hop oil were determined in a simple model solution (4% ABV) using a newly established attribute lexicon and following a Quantitative Descriptive Analysis (QDA) approach. The fractions induced a range of different aroma and flavour sensations, which could partly be attributed to specific hop aroma compounds. The most polar compounds in the terpene alcohol fraction were suggested to be responsible for cross-modal interactions eliciting both aroma and/or taste and trigeminal sensations. A peppery tingling mouthfeel was perceived, which is assumed to be a sensation innervated by the trigeminal nerve. The terpene alcohol fraction was further categorised into monoterpene alcohols (i.a. geraniol, linalool) assumed to be mainly responsible for olfactory sensations and sesquiterpene alcohols (i.a. humulol, humulenol II) to foremost induce gustatory and tactile sensations. Further fractionation specifically targeting single compounds and compound groups (sub-fractions) that were added to a commercial lager beer base (4.5% ABV) to measure the impact of perceptual interactions between compounds and the beer matrix using a revised attribute lexicon and adjusted dosage rates. A clear cause-effect-relationship could be located between geraniol and the sweet taste perceived in the beer. Geraniol also induced a smooth bitterness, which was opposed by the harsh bitterness quality added by sesquiterpene hydrocarbons. Linalool was classified as a aroma/flavour ‘enhancer’ rather than individually contributing to the sensory profile. Significant effects on lingering mouthfeel sensations remained absent, which illustrated the need for temporal sensory assessments to adequately and holistically discriminate the samples with regard to these sensations. A Temporal Check-All-That-Apply (TCATA) by modality approach was used to assess multiple sensory characteristics of selected hop flavour products perceived simultaneously. The products contained the previously studied hop oil fractions and were combined with either iso-alpha-acids or oxidised beta acids (hulupones) in a lager base beer brewed without any hop materials. Bitter acid extracts were found to significantly affect the duration and sensory profiles of the hop flavour products in the beer suggesting a sensory interaction induced by the co-occurrence of hop aroma compounds and hop bitter stimuli. Lingering sensations (peppery tingling, astringency) were foremost found to significantly discriminate between the samples at the end of the evaluation period (>2min). Since temporal sensory data is inherently noisy, a part of this research included the examination of TCATA data pre-processing approaches using comprehensive statistical analyses. This revealed that time standardising the TCATA by modality data could not remove inter- and intra-individual variation between the panellists and thus, not improved the quality of the sensory data. This research has provided new and in-depth knowledge on the sensory properties of scCO2 hop oil fractions, sub- fractions, and key compounds extracted from Magnum hop. Moreover, different sensory characterisation strategies and tools are presented that captured the fine nuances of the sensory profiles of these hop extracts. The findings demonstrated the involvement of hop volatile compounds in sensory interaction effects causing multi-modal profiles in beer. Their ability to modify gustatory and trigeminal sensations should be considered for future developments of flavour preparations.
... The synthesis and the complex profile of hop essential oils is highly genotype-dependent and strongly influenced by environmental and cultural conditions [14]; the hop aromatic profile is constituted mainly by three chemical groups: hydrocarbons (50-80%), oxygenated compounds (20-50%) and organosulfur compounds (<1%) [15]. Among hydrocarbons, the most representative fraction is represented by terpenes that, being highly volatile, tend to vanish during the brewing process [16][17][18]. The oxygenated fraction, composed by a mixture of alcohols, aldehydes, ketones, epoxides, esters and acids, is H 2 O-soluble and significantly contributes to beer organoleptic properties [17]. ...
Background: Northern Italy has an enormous heritage of hop biodiversity that need to be exploited and studied. The preservation and valorization through the characterization of the existent biodiversity is a primary goal of the European Green Deal 2023–2030. The aim of this study was to acquire information on the biodiversity of Italian wild hops. Methods: Genetic characterization of sixty accessions was done resorting to Single Sequence Repeated (SSR) markers. Phytochemical characterization of wild hops was achieved using: (i) high-performance liquid chromatography with ultraviolet detection for bitter acids quantification, (ii) steam distillation for essential oils quantification and (iii) Gas Chromatography-Mass Spectrometry for the determination of the aromatic profile. Results: The eight SSR primers showed high Polymorphic Information Content (PIC), especially HlGA23. α-Acids reached values between 0 and 4.125. The essential oils analysis highlighted variability within the studied population, with some accessions characterized by important spicy fraction, and others by fruity and floral notes. Conclusions: The present study allowed the characterization of Italian wild hops and demonstrated an interesting biodiversity. Part of this biodiversity have been shown to be potentially suitable for use in brewing. Moreover, several genotypes could be used in breeding programs to obtain new more sustainable varieties.
... We found data on the recommended daily intake of β-myrcene [17][18][19], but not on the quantity of beer that can be consumed safely. Since diet is considered to be the greatest source of human exposure to β-myrcene there is a paucity of information on the subject. ...
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.
... 131 Ele contribui para o sabor da pimenta-do-reino (Piper nigrum L. com 13,2% de cariofileno e 1,6% de a-humulene), 132 orégano (Origanum vulgare L.), 133 alecrim (Lippia graveolens) 134 e lúpulo (Humulus lupulus). 135 Normalmente, o a-humuleno ocorre em menor proporção junto com o cariofileno nas mesmas plantas, mas no lúpulo ele é o responsável pelo aroma das cervejas. Esses dois sequiterpenos estão presentes em vários óleos essenciais e têm diversificadas atividade biológicas, principalmente no que diz respeito às atividades anti-inflamatórias. ...
... Conversely, EOs do not affect the bitterness, but are responsible for the aroma. They bring citrus-like, floral, fruity notes, spicy, woody, herbal and grass aroma fragrances, depending on the variety of the hops used and their cultivation environment [6,7]. The EO produced by Humulus lupulus L. can be divided into three subgroups: hydrocarbons, oxygen-bearing components and sulfur-containing molecules. ...
Interest in essential oils has consistently increased in recent years. Essential oils have a large variety of applications in multiple fields, including in the food, cosmetics and pharmaceutical industries. The volatile fraction (VF) in hops (Humulus lupulus L.) fits within this domain as it is primarily used in the brewery industry for the aromatization of beer, and is responsible for the floral and fruity tones. This work aims to design an optimized extraction protocol of the VF from hops, using microwaves. Microwave-assisted hydrodistillation (MAHD) has been developed to reduce energy and time consumption in lab-scale reactors up to industrial-scale systems. Hops are principally available in three forms, according to a brewery’s applications: (i) fresh (FH); (ii) dried (DH) and (iii) pelletized (PH). In this work, all three forms have therefore been studied and the recovered volatiles characterized by means of GC-MS. The optimized lab-scale MAHD protocol gave the best extraction yield of 20.5 mLVF/kgdry matrix for FH. This value underwent a slight contraction when working at the highest matrix amount (3 kg), with 17.3 mLVF/kgdry matrix being achieved. Further tests were then performed in a pilot reactor that is able to process 30 kg of material. In this case, high yield increases were observed for PH and DH; quadruple and double the lab-scale yields, respectively. In addition, this industrial-scale system also provided marked energy savings, practically halving the absorbed kJ/mLVF.
... Several studies have focused on their chemical characterization by GC-MS analysis. Usually, the main constituents are myrcene, humulene and caryophyllene [1][2][3][4][5][6]. To our knowledge there are five botanical varieties of hops (var. ...
Featured Application
This work could lay the foundation for future hop breeding research; moreover, the results of this research answers to the brewers’ question of how territory, in this case the Corsican territory, influences aromatic and morphological characters of cultivars.
Abstract
Hops (Humulus lupulus L.) is a species that grows spontaneously in Corsica, but the characterization of this species in this territory has not yet been investigated. The main objectives of this study are to explore the features of wild hops from Corsica and to determine the effect of the island terroir on some cultivars in the first year of growth. A multidisciplinary approach consisting of the genetic analysis, morphological comparison and chemical characterization of essential oils was carried out on four wild Corsican hops and three hop cultivars grown in Tettnang, Germany and Corsica, France. The morphological and GC-MS analysis of Corsican wild hops, set cluster coastal samples apart from the one far from the coast. This dissimilarity is supported by the SSR analysis by two of the three coastal accessions. The genetics demonstrate a proximity between the European noble cultivar Tettnanger and the mountain Corsican wild hop from Corte. The morphological comparison between German hops cultivated in Tettnang and in Corsican soil, and the GC-MS characterization of their essential oils’ chemical profiles, show different features between year 0 and year +1 for each sample. This multidisciplinary approach highlights an acclimatization of hop cultivars to the Corsican terroir one year after planting.
... Figure 1 shows the chromatogram of a lemon flavored beer in which lemon juice has been added as flavoring agent. Myrcene is the principal volatile of most hop varieties, and is a significant contributor to fresh hop aroma [23,24]. Its concentration decreases during the brewing process due to autoxidation, giving rise to multiple cyclic reaction products (e.g., α-pinene, β-pinene, camphene, p-cymene) and also forms terpenoids such as linalool, nerol, geraniol, citral, αterpineol, or carvone [25]. ...
In the last few years, the flavored beer market has increased significantly. In particular, consumers showed a growing interest in citrus-flavored beers. Citrus fruits contain, among other class of compounds, terpenes and terpenoids and oxygenated heterocyclic compounds. The absence of a specific legislation concerning beer flavored production and ingredients reported on the labels makes these beers subject to possible adulterations. Solid phase micro extraction (SPME) followed by gas chromatographic–mass spectrometry (GC-MS) and gas chromatographic-flame ionization detector (GC-FID) analysis of the volatile profile together with the characterization of the oxygen heterocyclic compounds through high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) demonstrated to be a powerful analytical strategy for quality control. In this study, we combined the volatile and non-volatile profiles of “citrus flavored mainstream beers”, in order to evaluate the authenticity and determine markers to prevent food frauds. The changes in the aroma composition of the unflavored types after the addition of peel, or citrus essential oil were also evaluated. The linear retention index (LRI) system was used for both techniques; in particular, its application in liquid chromatography is still limited and represents a novelty. The coupling of the high sensitivity of the HPLC MS/MS method with the LRI system, it has made possible for the first time a reliable identification and an accurate quantification of furocoumarins in citrus-flavored beers.
... Linalool is traditionally considered to be the indicator of hoppy aroma intensity, [36,37] while 6-methyl-5-hepten-2-one is often reported to be a contributor to the citrusy, green aroma of many plants. [38][39][40][41] Thus, higher concentrations of total hydrophilic compounds indicate their contributions to the higher intensity of hoppy aroma. Indeed, these varieties are effective contributors to the intense aroma of beer even when dosed at low quantities. ...
Beers hopped with 79 varieties were brewed in small-scale fermenters, and 127 hop-derived compounds were picked up by comparing with the chromatogram of unhopped beer, after the analysis of the stir bar sorptive extraction gas chromatography-mass spectrometry method.
“Hop creep effect” could be seen, that is, larger amounts of hop pellets in the wort resulted in lower concentrations of the apparent extracts of the beers.
The 127 hop-related flavor compounds were used to examine the interrelationship with the hop varieties by principal component analysis (PCA). Different varieties and amounts of hop pellets based on equal amounts of alpha-acids were added to the cooled wort. Addition of higher amounts of hops resulted in lower concentrations of apparent extracts of beer, suggesting the presence of dextrin-hydrolyzing enzymes in the hops. PCA largely established five directions. Direction I including Cascade, Amarillo, Citra, Simcoe, Mosaic, Wai-iti, and Hallertau Blanc varieties was linked to geraniol and citronellol, both known to contribute to citrus characteristics. Direction II including Bobek, Styrian Gold, and Moutueka varieties was associated with linalool and 6-methyl-5-hepten-2-one. Direction III including Hersbrucker and Saphir was linked to sesquiterpene alcohols. Direction IV was associated with hydrophobic monoterpenes, and direction V was linked to hydrophobic sesquiterpenes. Further study of these hop varieties and constituents can help advance our knowledge in using different hop varieties to achieve defined aroma and taste of beer.
... Also known as α-caryophyllene, its formula is C 15 H 24 . It is named after the essential oil of the species Humulus lupulus [61]. It has anti-inflammatory [62,63] and anticancer properties [64]. ...
Secondary metabolites from plant organisms have always been excellent options for the pharmaceutical, cosmetic, and food industries. Essential oils are a type of metabolites found in vegetables, and their chemical composition is diverse; however, monoterpenes and sesquiterpenes are inside the most abundant molecules. These terpenes have a diverse chemical composition that range from a simple molecule with carbon and hydrogen to more complex molecules with oxygenated organic groups, such as alcohols, aldehydes, ketones, and ethers. Many of these molecules with 10 and 15 carbon atoms have an especially important biological activity, being important the antimicrobial, antifungal, antioxidant, anti-inflammatory, insecticide, analgesic, anticancer, cytotoxic, among others. Some of these substances are potentially toxic, and hence, they should be handled with caution, especially when they are pure. They are easily obtained by different methods, and their industrial value grows every year, with a market of several million dollars. This chapter seeks to provide a better understanding of this type of bioactive molecules, with an emphasis in those whose information is remarkable in the scientific literature and whose value for health and human well-being makes them extremely important.
... These cones hold glandular trichomes that store the major substances of commercial importance in the species (Almaguer et al., 2014). Around the world, the brewing industry uses H. lupulus L. flowers as an essential component in the brewing process, as they are responsible for their bitterness and aroma (Silva and Faria, 2008;Nance and Setzer, 2011). ...
Hop (Humulus lupulus L.) is a plant with economic importance due to its use in the brewing industry. The cones produced by the species contain the main substances responsible for the beer's bitterness and aroma. Hop plants cultivation in Brazil is still incipient and information on efficient methods for its propagation in this context are scarce. The objective of the present study was to evaluate the effect of different leaf areas (two whole leaves, two leaves in half, one whole leaf, one leaf in half and without leaves) in herbaceous stem cuttings planted in environments with and without intermittent misting. The experiment was conducted in a greenhouse in Curitiba-PR, Brazil (25°25'40 "S and 49°16'23" W). After 30 days of planting, the survival, rooting, sprouting and leaf retention percentages, roots number, average roots length and roots and sprouts dry mass were evaluated. Cuttings with one or two whole leaves and two leaves in half in the misting environment showed the highest rooting percentages (between 90.0 and 97.5%). In the without misting environment, the highest values were observed in cuttings with one or two leaves in half and one whole leaf (between 62.5 and 72.5%). Leafless cuttings had low survival percentages (2.5% in both environments). Under intermittent misting conditions it is recommended to prepare stem cuttings with one or two whole leaves and, in the absence of control over the environment humidity, cuttings with one whole leaf are recommended.
... Female plants are economically important due to the use of their flowers in the brewing industry (KARABÍN et al. 2016). The female inflorescences, also referred to as cones or strobiles, hold the lupulin glands, structures secreting secondary metabolites such as bitter acids and essential oils, which give the characteristic bitterness and aroma to beer (NANCE, SETZER, 2011;DURAISAMY et al. 2016;KARABÍN et al. 2016 programs and, therefore, the determination of seed quality and standardization of germination tests are strategic approaches for the efficient production of new cultivars. Hop seeds are known to present low germination percentages due to dormancy (SUCIU et al., 1977;LIBERATORE et al., 2018), making it necessary to study specific treatments to promote germination as well as the elucidation of specific aspects of dormancy in the species. ...
Brazil is the world's third largest beer consumer and currently imports all of its hops for the brewing industry. Such a fact justifies the selection of hop genotypes adapted for cultivation locally, which requires high quality seeds and efficient sex determination of the seedlings. The objectives of this study were to develop a methodology to assess hop seed quality and to efficiently determine hop seedling sex through the use of male-specific molecular markers. Freshly harvested hop seeds were germinated with and without pre-chilling (3-5 ° C) for 3, 6 and 12 weeks and then germinated at 20 or 25 ° C in the presence or absence of light, evaluating germination percentage and germination speed index. F1 progenies were obtained from after seed germination in a greenhouse and seedlings sex was determined using male-specific molecular markers. The best conditions for physiological quality assessment of hop seeds used in the present study were pre-chilling for 12 weeks, followed by germination at 25 ° C, and normal seedling counts at 7 and 15 days. The progeny submitted to molecular marker sexing was composed of 61.3% female plants. The established methodologies presented here can be considered efficient and may contribute to expedite hops breeding programs.
... Myrcene varies from variety to variety and can contain from 10 to 72% of the "hop oil". This compound bestows the green fresh note with resinous aspects (Steinhaus and Schieberle, 2000;Nance et al., 2011). Myrcene's oxidation forms many terpenoids, such as linalool, geraniol, citral, a-terpineol and carvone, known for their augmenting effects on the aroma (Dieckmann and Palamand, 1974;Rettberg et al., 2018). ...
This paper investigates the process of extracting hop pellets (hops) utilizing the pulsed electric field (PEF) technique and the contrasting effects of the technique between two distinct hop varieties (one bitter and one aromatic). The effect of PEF on the extraction was evaluated by measuring the concentration of α-acids and β-acids (humulones and lupulones). Regarding the aromatic character, the hop’s volatile caryophyllene, humulene and β-myrcene were analyzed both with and without employing the PEF treatment. In order to analyze the acids and the volatile fraction, the analytical method of UV–vis spectrophotometry was applied followed by gas chromatography coupled with mass spectrometry. For the second technique, the extracts were previously purified through a Graphitized Carbon Black syringe for Solid Phase Extraction. The results revealed that PEF had a positive impact on the alpha acids of bitter hops by increasing the extraction rate of these acids by 20%, while the volatiles demonstrated an increase of 5.6 and 7.4% for humulene and caryophyllene, respectively. Concerning the aromatic variety of hops, the PEF treatment appeared to have no noteworthy effects.
... Myrcene is the principal volatile of most hop varieties and it is related to resin-, pine-, and herb-like and significantly contributes to fresh hop aroma. Its concentration decreases strongly during aerobic hop storage and during the brewing process (Steinhaus and Schieberle, 2000;Nance et al., 2011). ...
... Aroma compounds in hops are important because they make a major contribution to the quality of the final product [1]. The aroma of beer has been studied extensively for several decades, and compounds have been identified that are responsible for flavor [2]- [5]. Hops are added during the brewing process for bittering purposes but also to impart hop-derived aroma to the final beer product [6], [7]. ...
... [12][13][14] For centuries the female inflorescences were primarily used for their flavoring and antiseptic properties, [15,16] but modern brewers are presently more interested in their bitter and aromatic contributions to beer, the latter derived from the essential oils sequestered within its resins. [15,[17][18][19][20][21] The relative composition of essential oils and chemical composition of hops, comprised predominantly of terpene and sesquiterpene hydrocarbons, can vary amongst the available commercial hop varieties and individual cultivars. [13,18,[22][23][24][25][26][27][28][29][30][31] Within species genotypic variation has been shown previously to influence the plant-associated microbiomes, [4,32] and the central objective of this study was to determine for hops whether the resident microbial community differs amongst hop varieties and whether the drying process alters the community composition. ...
The aerial portion of plants (phyllosphere) harbors complex and diverse microbial
communities that have been shown to influence host growth and fitness, tolerance to
environmental stressors, disease susceptibility, and the productivity of economically
significant crops. However, despite its reproductive importance to the host and
economic value, the microbial ecology of anatomical flowers (anthosphere) remains
largely uninvestigated. Here we report a culture-independent assessment of bacterial
communities on freshly harvested and dried inflorescences of eight hop varieties
(Humulus lupulus L.) using Illumina MiSeq 16S platform-based rRNA gene sequence
analysis. The results reveal the hops anthosphere is dominated by a single taxonomic
phylum, the Proteobacteria, where at least 60% of the sequences are attributed across
two genera, Pseudomonas (Gammaproteobacteria) and Sphingomonas
(Alphaproteobacteria). Chao1 diversity analysis indicated the presence of many very
rare taxa across all varieties. Beta-diversity analysis resolved, from the comparison of
unweighted and weighted UniFrac distances, the absence of distinct clustering
between freshly harvested and dried hops or between hop varieties. The prevalence of
Proteobacteria associated with hop inflorescences is consistent with other anthosphere
microbiomes; however, presently the predominance of Gammaproteobacteria in the
phyllosphere appears to be a distinct characteristic of the hops microbiome.
... Compared to hop cone extracts, H. lupulus leaves contain a much smaller concentration of volatile compounds (0,05% vs. 2%) (Katsiotis et al., 1990). A large number of hop cultivars exist, each with its own aromatic profile, ranging from fruity or herbal to musty or earthy (Eyres et al., 2007;Meilgaard et al., 1982;Nance and Setzer, 2011). Spent hops from brewing have been shown to have a repellent effect on storage beetles (Bedini et al., 2015;DeGrandi-Hoffman et al., 2012) while Jones et al. (2003Jones et al. ( , 1996 have shown a repellent effect of hop extracts on the two-spotted spider mite (Tetranychus urticae Koch). ...
... Compared to hop cone extracts, H. lupulus leaves contain a much smaller concentration of volatile compounds (0,05% vs. 2%) (Katsiotis et al., 1990). A large number of hop cultivars exist, each with its own aromatic profile, ranging from fruity or herbal to musty or earthy (Eyres et al., 2007;Meilgaard et al., 1982;Nance and Setzer, 2011). Spent hops from brewing have been shown to have a repellent effect on storage beetles (Bedini et al., 2015;DeGrandi-Hoffman et al., 2012) while Jones et al. (2003Jones et al. ( , 1996 have shown a repellent effect of hop extracts on the two-spotted spider mite (Tetranychus urticae Koch). ...
The genus Humulus currently includes 7 listed species that have common but also differentiating chemical characteristics. Due in particular to their richness in original specialized metabolites, the female infructescences of hop are widely used as a bittering, aromatic and stabilizing ingredient in beer. Wild hops are chemically more diverse than cultivars that come from a common gene pool. Initially oriented towards the study of disease resistance and productivity potential, research on wild hops has exploded in recent decades and in various countries to focus on the search for organoleptic qualities. Wild hops have been hybridized with cultivars, intentionally or spontaneously, giving rise to new original varieties thanks to the heritability of their chemical characteristics transmitted to their descendants. This research has proven itself with the development of cultivars with interesting organoleptic qualities for hopping beer. Depending on the hopping technique used, which has diversified considerably in recent decades, hop compounds undergo numerous chemical reactions during the brewing process, offering the brewer a wide organoleptic spectrum in terms of bitterness and aromas. The volatile compounds of hops, from the more classic terpenes to polyfunctional thiols, have been particularly studied in recent years due to the search for new varieties rich in original aromas.
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.
. In Ukraine, hops are basically processed into Type 90 pellets, that are practically indistinguishable in terms of biochemical indicators from hop cones. Pellets of hop are the single domestic source of hop products that can be serve as an alternative to imported pellets and extracts that used in the Ukraine brewing. Comprehensive studies of the evaluation of Type 90 hop pellets of aromatic and bitter varieties produced in Ukraine and European countries allowed establishing that they have different biochemical compositions and consequently, different brewing value. That have been identified differences in the absolute values of indicators such as the mass fraction of alpha acids, beta acids and their composition, xanthohumol, essential oil, the ratio of valuable hop compounds: beta acids to alpha acids and components of the essential oil. It has been determined that in hop pellets of aromatic varieties, the content of alpha acids changing from 3.3% in the Klone 18 variety to 5.9% in the Hallertauer Tradition variety. The content of beta acids, in the investigated pellets, ranges from 3.6% (Klone 18) to 6.7% in the Slavyanka variety. It is established that the hop pellets made from Ukrainian varieties Zagrava and Slavyanka have significantly higher content of beta acid 6.3% and 6.7%, respectively, compared to pellets of foreign varieties. There is a significant advantage in the resin fraction of beta acids over the fraction of alpha acids in the pellets of Slavyanka, Klone 18, Zhatetsky and Zagrava varieties, that they meaning retain a positive coefficient of aromaticity between the content of beta and alpha acids that ranges from 1.18 to 1.37. The content of alpha acids ranges from 8.7% in the Polisky variety to 14.1% in the Magnum variety in the hop pellets of bitter varieties. The content of beta acids in the same pellets ranges from 4.2% to 5.9%. It has been established that the composition of alpha and beta acids in the investigated pellets changes depending on the variety. It has been proven that Ukrainian-produced hop pellets correspond to their international counterparts in terms of their characteristics. Specifically, the biochemical and technological indicators of Klone 18 hop pellets correspond to the characteristics of pellets of the Czech variety Zhatetsky, pellets made from the bitter variety Alta correspond to the biochemical indicators of German Magnum pellets but pellets of varieties such as Slavyanka and Zagrava exceed the world analogies in terms of the composition and quality of bitter substances and essential oil. Based on the comparative biochemical characteristics of Type 90 hop pellets of Ukrainian and European production, the quality of Ukrainian hop products has been found to be at a global level. Certified domestic hop products, specifically Type 90 pellets, can be used do not only by Ukrainian brewers but also by other manufacturers to create new innovative and competitive products with various functional purposes.
Dry-hopping is the addition of hops to the wort on the cold side of the brewing process. Unlike standard hop additions, its main purpose is not to produce a characteristic bitterness but to extract as much of the hop essential oils as possible, which are largely lost in the standard hopping process. When dry-hopped, it is possible to obtain a beer with an aroma that is difficult to achieve when hops are used on the hot side of the brewing process. As a result, this process has become very popular in recent years, particularly in beers that belong to the ‘craft beer revolution’ trend. In addition, the usefulness of this process is increasing with the development of new hop varieties with unique aromas. This article presents the main components of hops, focusing on those extracted during the process. Changes in the composition of beer bittering compounds and essential oils resulting from this process are discussed. This paper presents the current state of the knowledge on the factors affecting the degree of extraction, such as hop dosage, the time, and temperature of the process. Issues such as process-related physicochemical changes, hop creep, low flavor stability, haze formation, and green flavor are also discussed.
In this experiment, two hops varieties Simcoe and Saaz were selected as the research objects to explore the influence of hops on beer flavor after aging treatment under different conditions. The hops obtained under five different aging conditions were subjected to fermentation experiments. The aroma characteristics of hop oil, beer samples at different brewing stages and finished beer were analyzed by gas chromatography-mass spectrometry (GC/MS). The results showed that, except caryophyllene oxide (0.21 μ g/L and 0.15 μg/L), the contents of other aroma compounds decreased. The results of expert sensory evaluation and consumer evaluation survey were combined with the experimental data for analysis. We found that moderate aging may make beer more drinkable. Among them, hops represented by Simcoe with more aroma substances will lose their original aroma after aging. However, hops with higher humulus content represented by Saaz became softer after moderate aging treatment.
Hop (Humulus lupulus L.) is used in the brewing industry as a source of compounds responsible for the bitterness, aroma, and preservative properties of beer. In this study, we used microsatellite markers to investigate genetic diversity and genetic differentiation of wild hop populations sampled in the northwestern part of Croatia. Analysis of 12 microsatellite loci revealed high diversity and weak population differentiation among wild hop populations. A total of 152 alleles were determined with an average of 12.67 alleles per locus. Observed heterozygosity ranged from 0.689 to 0.839 (average 0.767) and expected heterozygosity ranged from 0.725 to 0.789 (average 0.760). A total of 38 private alleles were detected. The data suggest that H. lupulus populations are not affected by recent bottlenecks. The degree of genetic differentiation among populations was low and not significant for most pairwise FST values, except for the pair of geographically most distant populations. The results did not indicate the existence of genetic structure among the sampled populations. The high genetic diversity and low differentiation among populations, combined with the absence of isolation by distance, indicate the existence of substantial gene flow among wild hop populations. Therefore, extensive sampling per population is clearly required to assess the genetic diversity of hop populations. Sampling strategies involving sampling across a large number of localities represented by only a few samples could lead to erroneous conclusions.
Understanding the contribution of hop essential oil to the multisensory profile of beer is known to be challenging because of its chemical and sensory complexity. Limited research has been conducted investigating hop-derived volatiles' role in the modulation of taste and mouthfeel sensations. Supercritical CO₂ can be used to extract specific fractions from hop oil, thereby enabling the localisation of compounds responsible for different sensory impressions. Terpene alcohol and sesquiterpene fractions were extracted from a Magnum hop oil and further fractionated into seven sub-fractions and individual compounds. All extracts were evaluated in lager (4.5% v/v) by a trained panel (n=10) using a newly developed attribute lexicon and following a sensory descriptive analysis approach. The sensory data was analysed using ANOVA, followed by Tukey’s test (HSD) and correlated with chemical profile data obtained by gas chromatography-mass spectrometry (GC-MS) by Principal Component Analysis. The study revealed evidence for hop extracts to impart multisensory characteristics to beer due to sensory interactions within and across modalities. The monoterpene alcohols-rich fractions and particularly geraniol, added fruity- and floral aromas and flavours, modified the sweetness and induced a smooth bitterness in the beer matrix. Flavouring the beer with sesquiterpene fractions resulted in a harsh bitterness sensation. Contrary to previous findings, the humulene epoxides fraction appeared to have limited effects on lingering bitterness and astringency, illustrating the need for temporal sensory assessments in future studies. This research shows that splitting hop oil into fractions and sub-fractions provides a source of natural, sustainable flavouring preparations with distinct sensory characteristics.
Cladanthus eriolepis (C. eriolepis) (Coss. ex Maire) Oberpr. & Vog. is endemic to High Atlas (Dades Gorge and Todgha Gorge), the Anti Atlas and Saharan Morocco. It is known under the vernacular names ‘Alougjim, gtaa-eddib, laatetecha’ and ‘Lamghizal’. Two essential oil samples have been isolated from aerial parts and analyzed by combination of chromatographic and spectroscopic techniques [gas chromatography (GC) in combination with retention indices (RI), gas chromatography-mass spectrometry (GC/MS) and ¹³C-NMR spectroscopy]. The compositions of both oil samples were dominated by hemiterpene esters such as isobutyl isobutyrate (21.2% and 20.8% respectively) and isobutyl angelate (22.0% and 22.4% respectively). Other esters present at appreciable contents were 2-methylallyl isobutyrate (5.3% and 5.5%), 2-methylbutyl isobutyrate (5.7% and 5.8%), 2-methylallyl angelate (4.6% and 4.9%) and 2-methylbutyl angelate (7.7% and 7.2%) beside α-pinene (9.5% and 5.8%) and β-bisabolene (2.8% and 4.0%). The compositions of the investigated oil samples from C. eriolepis differed substantially with literature data and with those of other Cladanthus species growing wild in Morocco.
INTRODUCCION Desde el punto de vista de la inocuidad, no hay ningún tipo de microorganismo que pueda reproducirse en la cerveza y enfermar a las personas. En términos generales, la calidad de la cerveza se refiere al cumplimiento y la consistencia de las especificaciones o propiedades sensoriales que definen un determinado estilo, sumado a la ausencia de sabores indeseables. Por su parte, el consumidor conocedor y devoto de la cerveza artesanal busca que la misma sea auténtica, bien hecha, singular, atractiva y confiable, lo que bien podría ser otra definición para una cerveza de calidad (Gigliarelli, 2017). Lograr una cerveza de calidad implica mucho más que seguir una receta. Por un lado, se necesita conocer que ingredientes son los de mejor calidad y cuál es su disponibilidad, así como tener un conocimiento acabado de las etapas del proceso. Por otro lado, se debe contar con instalaciones y equipos que cumplan las normas sanitarias y alimentarias así como la capacitación constante del personal en todas las áreas, incluyendo Buenas Prácticas de Manufactura (BPM) (Steele, 2013). El presente artículo analiza aquellos aspectos de los ingredientes y los procesos de la cerveza que determinan el perfil sensorial de la misma. Además, resume algunos de los métodos analíticos más utilizados para el análisis y control de estos parámetros sensoriales. Por último se destacan las actividades realizadas por el Núcleo Cerveza del Laboratorio de Tecnología de Alimentos (LabTA), el cual está avanzando en investigación, extensión y formación sobre cervezas (Figura 1). RESUMEN La cerveza es un elixir elaborado a partir de cuatro elementos: agua, malta, lúpulo y levadura. Su proceso se ha perfeccionado al paso de los años y se puede considerar a esta bebida como una de las más antiguas en el mundo. El resurgimiento de la cerveza artesanal en los últimos años, trajo consigo una demanda de excelencia. La calidad de la cerveza hace referencia a parámetros sensoriales relacionados con el estilo, como el amargor, dulzor, sequedad, carácter de la malta, intensidad del lúpulo y similares. Por otro lado, debe estar ausente o regulada de aromas y sabores "no deseados" como diacetilo (mantequilla), acetaldehído (manzana verde), fenoles (clavo de olor) y oxidación (cartón/áspero/rancio), entre otros. Dado que es una bebida tan popular en todo el mundo, estar familiarizado con las técnicas analíticas adecuadas para la evaluación de la cerveza es útil para investigadores y cerveceros. Este artículo tiene como objetivo resumir los diversos ingredientes y procesos de la cerveza que originan los compuestos determinantes del aroma, sabor, cuerpo, espuma y demás atributos considerados al momento de valorar la calidad de una cerveza. La técnica de cromatografía de gases (GC) y espectrometría de masas (MSD) sumado a la microextracción en fase sólida (SPME) es la técnica convencional para la detección e identificación de compuestos aromáticos volátiles. Los mismos compuestos pueden percibirse mediante un análisis sensorial, utilizando un panel entrenado o bien un grupo de enfoque (Focus Group). El Núcleo Cerveza del Laboratorio de Tecnología de Alimentos (LabTA) de la FCA-UNC, demostró mediante un estudio realizado en el año 2019, que el uso de SPME-GC-MSD es un método efectivo para detectar volátiles de diferentes familias químicas en cervezas rubias y negras de la Ciudad de Córdoba. El mismo estudio midió la aceptabilidad de cervezas mediante un Focus Group (grupo de enfoque) utilizando una escala hedónica de 9 puntos y la apreciación de ciertos descriptores de cerveza optimizados para nivel consumidor.
The volatile compounds from rosemary dried leaves were extracted and than separated and identified by gas-chromatography coupled with mass-spectrometry. Different quantities (0.15g; 0.5g; 1g) of dried rosemary leaves were incubated at various temperatures (30 o C; 40 o C; 60 o C; 75 o C; 80 o C; 95 o C) and periods of time (15'; 30'; 40'). A number of 4 to 28 compounds were separated and identified from rosemary dried leaves, depending on the used method. In all cases, the major compound of rosemary was α-pinene (46.52 - 72.45%), followed by camphene (6.54 - 14.03%), 3-octanone (2.97 - 7.84%), and eucalyptol (2.94 - 8.87%). By increasing the incubation temperature, the incubation time or the quantity of necessary sample may be reduced, the obtained results being similar with those obtained for the same incubation temperature but for a larger incubation time or quantity of sample.
Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to determine the aromatic composition and aroma active compounds of fruit juice and peel oil of Jinchen sweet orange fruit. Totals of 49 and 32 compounds were identified in fruit juice and peel oil, respectively. GC-O was performed to study the aromatic profile of Jinchen fruit juice and peel oil. A total of 41 components appeared to contribute to the aroma of fruit juice and peel oil. Twelve components were the odorants perceived in both samples. The aromatic compositions of fruit juice were more complex than that of peel oil. Ethyl butanoate, β-myrcene, octanal, linalool, α-pinene, and decanal were found to be responsible for the aromatic notes in fruit juice and peel oil. Nineteen components have been perceived only in the juice and ten compounds were described as aromatic components of only the peel oil by the panelists. These differences lead to the different overall aroma between fruit juice and peel oil.
The aim of this study was to assess the stability during storage of several compounds previously described for distinguishing hop varieties. Volatile compounds of five aromatic cultivars (Styrie, Saaz, Lublin, Mount Hood, and Hallertau) and six bitter cultivars (Northern Brewer, Nugget, Pride of Ringwood, Northdown, Target, and Challenger), stored at different temperatures, were extracted with a Likens-Nickerson simultaneous solvent extractor. Only compounds remaining stable through aging were kept to build an identification flowchart. Although very typical of fresh aromatic hops, farnesene proved much too unstable to be selected for distinguishing aged samples. 3-Methylbutylisobutyrate, which authenticates all fresh European bitter hops, is also partially destroyed upon storage. On the other hand, bergamotene, α- and β-selinene, methyl geranate, humulene epoxide II, α-amorphene, 2-undecanone, and an unknown compound can be used to distinguish all cultivars whatever the storage temperature. Both the ratios of humulene to humulene + humulene epoxides (I, II, and III) and of bergamotene to farnesene proved good indicators of the freshness status of hop samples.
The influence of γ-irradiation at doses from 5 kGy to 30 kGy on oregano (Origanum vulgare L.) was studied by the conventional microbiological analysis tests and by the combination of GC-FID; GC-MS; GC-Olfactometry (GC-O); EPR and UV-VIS spectroscopy. Microbiological analysis proved that γ-irradiation at 7.5 kGy was sufficient to achieve the microbiological decontamination of oregano samples, persisting even after 8 months of storage. The study of γ-irradia-tion impact on essential oils' composition and on organoleptic quality changes, evaluated using GC-FID, GC-MS, and GC-O involving the Aroma Extract Dilution Analysis (AEDA) method revealed no changes in the chemical composition and non-considerable changes in the content of volatile oils' compounds at samples γ-irradiated up to 10 kGy. Only non-significant changes of flavours upon the radiation treatment even at dose of 30 kGy were noticed. The analysis of EPR spectra confirmed the presence of two signals in a reference sample, attributed to Mn2+ ions and to stable semiquinone radicals. In addition, the dose-dependent formation of radicals of different origin (mostly cellulose and carbohydrate) showing the diverse thermal stability and life-time was noticed in γ-irradiated samples. UV-VIS experiments confirmed that the antioxidant activity of oregano ethanolic extracts was only slightly affected by the absorption of γ-radiation.
Pure individual analogs and stereoisomers of the major α-acids, β-acids, cis and trans-iso-α-acids, cis and trans-ρ-iso-α-acids, tetrahydrodesoxy-α-acids, tetrahydro-α-acids, and cis and trans-tetrahydroiso-α-acids have been prepared and isolated using fractional recrystallization, complexation, pH partitioning, and various Chromatographic techniques (including preparative normal phase and reverse phase). Their structures were determined by elemental analysis, 1H and 13C NMR, chirooptical methods, gas chromatography-mass spectrometry (MS), MS, UV, and high-performance liquid chromatography. The configurations of cis and trans-iso-α-acids were characterized to help establish the mechanism for the formation of ρ-iso-α-acids. The stereochemistry of tetrahydroiso-α-acids, prepared from α-acids and β-acids, has been clarified. The availability of these pure standards simplifies the analytical procedures, allowing the brewer to take full advantage of the various bittering agents.
A standard method for distinguishing the essential oils in hops has been developed. Factor, rotation-factor analyses have been used as well as correlation between gas chromatography and organoleptic estimation of aroma. A model for distinguishing 14 groups of oils using 31 descriptors has been developed utilising the variability of components in essential oils. The results are valid for the oils from older established plants, picked at full maturity in Slovenia.
The composition of essential oil in hops depends mainly on hop variety and less on growing, processing and storage conditions. Therefore the data on the composition can be used to distinguish between hop varieties. During the years 1998–2000, 78 samples of the commonly grown varieties in Slovenia were analyzed by gas chromatography. Research was focused on the selection of suitable components characteristic of the varieties in question. Since the changes in essential oil composition due to ageing are the most important interferences for determination of the varieties, these influences were successfully suppressed using the so-called indexes. Sixteen representative peaks were selected, indexes were calculated and processed by cluster analysis and principal component analysis. The developed method was shown to be effective on all hop varieties important in Slovenia and gave excellent results in daily laboratory practice.
A solid-phase microextraction (SPME) method is described for the determination of the essential oils, humulene and caryophyllene, in the headspace of female hop cones and male hop lupulin samples. Optimized SPME sampling parameters for the determination of the humulene to caryophyllene (H/C) ratio for female hops (50 mg) and male lupulin (25 mg) samples include a 100 μm poly(dimethylsiloxane) SPME fiber and a 4 h sample exposure period at a temperature of 50 °C. Increasing the temperature to 90 °C or increasing the length of sample exposure at 50 °C promoted caryophyllene oxidation. In a survey of five female hop varieties, good agreement was found between the H/C ratio obtained by headspace SPME and conventional steam distillation. The H/C ratio for 10 male lupulin varieties determined by headspace SPME and pentane extraction also indicated good agreement between the two extraction methods. Keywords: Hops; essential oils; SPME; headspace analysis
Two commercial American beers and two pilot-brew beers brewed with different hop varieties were analyzed by gas chromatography-mass spectrometry for hop-derived aroma compounds. The pilot brew made from Hallertauer mittelfrueh hops had significantly higher concentrations of α-terpineol, humulene epoxide I, humulol, T-cadinol, α-eudesmol, humulenol II, and 4,4-dimethylcrotonolactone than those of the pilot brew made from Washington Cluster hops. The commercial American beers analyzed were brewed with Oregon Cascade hops in one case and a mixture of Hallertauer (primarily), Tettnanger, and Styrian in the other. Caryolan-1-ol, nerolidol, humulene epoxide I, δ-cadinol, and α-eudesmol were present in the beer brewed with imported hop varieties, but they were absent in the beer brewed with the domestic hop. Sensory panel studies indicate that humulenol II may be a contributor to a fine hoppy aroma.
The essential oil of several varieties of hops displayed good varietal uniformity of composition under the following environmental conditions: annual climatic conditions, climates and soils of widely different growing areas within the United States, abnormal ranges of nitrogen and phosphorus fertility over various moisture levels, development of the plant over a 4-year period (hops are perennial), maturity of the crop over a 21-day harvest period, while hosting any of several viruses, through processing, and during storage. These observations were offered as justification for accepting hop oil composition as a reliable criterion for a system of varietal identification.
Four beers were analyzed by gas chromatography-mass spectrometry for hop-derived compounds. Two were commercial American beers, one brewed with 60% Cascade and 40% Cluster hops and the second with a mixture of European hop varieties. The other two beers were pilot brews, one made exclusively with Hallertauer hops and the other with Cluster. Linalool was found consistently in all beers. Geraniol and geranyl isobutyrate were found in high concentration in the Cascade beer and to a lesser extent in the Cluster beer. Neither compound was detected in the other two beers. Levels of geraniol and geranyl isobutyrate are much higher in Cascade hops than in most other varieties. Flavor threshold data for geraniol and linalool indicate they are responsible for the floral aroma/taste of beer brewed with Cascade hops.
Two American hop varieties, Washington-grown Cascade and Idaho-grown Hallertauer mittelfrüh, were chosen for this aging study and its effect on beer flavor quality. Prior to brewing, hops were refrigerated at 27°F (fresh), while one portion of the hops from the same bale was aged at 90°F for 2 weeks (aged I) and another portion for 9 weeks (aged II). Samples at each brewing stage were taken for chemical profile analysis. The finished beers were also submitted for flavor profile evaluations. Geraniol, linalool, and citronellol are mainly responsible for the floral/citrus note, while the oxidation products of α-humulene, especially the humulenol II and humulene diepoxides, contribute to the herbal/spicy note in beer. A grapefruit-like fruity flavor is also detected in beers brewed with extensively aged Cascade and Hallertauer hops. The survival of various hop-derived aroma compounds is also discussed.
The volatile components of bergamot (Citrus bergamia Risso) essential oil produced in Reggio Calabria in Italy were investigated using GC, GC–MS and gas chromatography–olfactometry (GC–O). Fifty-five compounds in the oil were identified by GC and GC–MS. The major compounds were limonene (37.2%), linalyl acetate (30.1%), linalool (8.8%), -terpinene (6.8%) and β-pinene (6.2%). In sensory analysis, odour description and flavour dilution (FD) factors of each component were evaluated by GC-sniffing and aroma extraction dilution analysis (AEDA). Bergamot-like odour components were (Z)-limonene oxide, decanal, linalyl acetate and geraniol. A mixture of eight other components, such as limonene, linalool, -terpinene and others, in addition to the four bergamot-like aroma compounds, brought about an aroma model of bergamot odour with the similarity of 7.1 by the nine-point-score sensory test. Copyright © 2006 John Wiley & Sons, Ltd.
The use of direct thermal desorption-gas chromatography-mass spectrometry (DTD-GC-MS) and DTD-GC-flame ionization detection (DTD-GC-FID) for characterization of hop essential oils is described. Four hop varieties (Nugget, Galena, Willamette, and Cluster) from the Yakima valley (Yakima, WA) 1998 harvest were analyzed by DTD-GC-MS and DTD-GC-FID methodology. Approximately 1 g of hops was needed for the analysis. Hop samples were prepared for GC-MS and/or GC-FID profiling in approximately 20 min. More than 100 volatile compounds have been identified and quantified for each hop variety. The results were found to be in good agreement with conventional steam distillation-extraction (SDE) data. A calibration curve for determination of essential oil content in hops by DTD-GC-FID has been generated. Quantitation of hop oil content by DTD-GC-FID was shown to be in good agreement with conventional SDE data. The recovery of key oil components valuable for varietal identification was demonstrated to be highly reproducible and characteristic of each variety analyzed when DTD-GC-FID was used for analysis.
Application of aroma extract dilution analysis on the volatiles obtained from dried cones of Spalter Select hops grown in the German hop-growing area of Hallertau revealed 23 odorants in the flavor dilution (FD) factor range of 16-4096, 20 of which could be identified. On the basis of high FD factors, trans-4, 5-epoxy-(E)-2-decenal, linalool, and myrcene were identified as the most potent odorants, followed by ethyl 2-methylpropanoate, methyl 2-methylbutanoate, (Z)-1,5-octadien-3-one, nonanal, (E,Z)-1,3, 5-undecatriene, 1,3(E),5(Z),9-undecatetraene, propyl 2-methylbutanoate, 4-ethenyl-2-methoxyphenol, and 1-octen-3-one. Ten of the high-impact hop aroma compounds had previously not been identified as hop constituents and, in particular, 1,3(E),5(Z), 9-undecatetraene has not yet been reported as a food odorant. In an extract obtained from fresh hops, in addition to the odorants found in dry hops, (Z)-3-hexenal was characterized as a further key odorant rendering an additional green aroma note to the fresh material.
The composition of hop essential oil is an important tool for evaluation of hop quality. As each hop variety has a typical essential oil pattern (fingerprint), hop oil analyses can be used to distinguish between hop varieties. The headspace solid-phase microextraction (SPME) method as described in this contribution is a simple sample preparation technique and represents an alternative procedure for essential oil fingerprint determination. Different SPME parameters (extraction temperature, extraction time and sample mass) were studied and the results were compared with those obtained by the routine distillation method. It is shown that SPME results can be used for determination and verification of varieties grown in Slovenia by means of principal components analysis.
This paper describes a sensorial aroma extract dilution analysis (AEDA) approach to the analysis of beer aromas derived from hops. To obtain an extract with an odor representative of the original product, the XAD extraction procedure was applied and the experimental conditions were optimized. The aromagrams of three beers were compared: one brewed without hops, one brewed with Saaz hop pellets, and one brewed with Challenger hop pellets. One spicy/hoppy compound, unmodified from hop to beer, proved responsible for the most intense odor in both hopped beer extracts. Another flavoring compound in hops, linalool, also survives through the process to the final beer. Other compounds such as gamma-nonalactone and humuladienone, although not found in our extracts of hop, significantly modify beer aromagrams after hopping. Sulfur compounds characteristic of Challenger hops proved to be at least partially responsible for the unpleasant flavor found in the corresponding beer.
3-(Trimethoxysilyl)propyl methacrylate (TMSPMA) was first used as precursor as well as selective stationary phase to prepare the sol-gel-derived TMSPMA-hydroxyl-terminated silicone oil (TMSPMA-OH-TSO) solid-phase mircroextraction (SPME) fibers for the analysis of aroma compounds in beer. TMSPMA-OH-TSO was a medium polarity coating, and was found to be very effective in carrying out simultaneous extraction of both polar alcohols and fatty acids and nonpolar esters in beer. The extraction temperature, extraction time, and ionic strength of the sample matrix were modified to allow for maximium sorption of the analytes onto the fiber. Desorption temperature and time were optimized to avoid the carryover effects. To check the matrix effects, several different matrices, including distilled water, 4% ethanol/water (v/v) solution, a concentrated synthetic beer, a "volatile-free" beer and a real beer were investigated. Matrix effects were compensated for by using 4-methyl-2-pentanol as internal standard and selecting the "volatile-free" beer as working standard. The method proposed in this study showed satisfactory linearity, precision and detection limits and accuracy. The established headspace SPME-gas chromatography (GC) method was then used for determination of volatile compounds in four beer varieties. The recoveries obtained ranged from 92.8 to 105.8%. The relative standard deviations (RSD, n = 5) for all analytes were below 10%. The major aroma contributing substances of each variety were identified via aroma indexes.
A simple and sensitive method for the analysis of beer volatile compounds was optimised using headspace solid-phase microextraction (SPME) and gas chromatography with mass detection. Headspace SPME using a 75 microm Carboxen-polydimethylsiloxane (CAR-PDMS) fiber provided effective sample enrichment and enabled extraction of a wide variety of compounds. The reproducibility depended on the compounds, with a mean value of 1.4% for alcohols, 3.3% for ethers, 6.7% for aldehydes, 3.4% for acids, 1.7% for aromatic compounds, 2.4% for esters, 7.4% for hydrocarbons, 1.8% for alicyclic compounds, and 3.4% for heterocyclic compounds. The optimised methodology can be used to compare volatile profile from different types of beers and eventually to study the evolution of a particular beer during aging.
The "spicy" character of hops is considered to be a desirable attribute in beer, associated with "noble hop aroma". However, the compounds responsible have yet to be adequately identified. Odorants in four samples of the spicy fraction of hop essential oil were characterized using gas chromatography-olfactometry (GC-O) and CharmAnalysis. Four hop varieties were compared, namely, Target, Saaz, Hallertauer Hersbrucker, and Cascade. Odor-active compounds were tentatively identified using comprehensive two-dimensional gas chromatography (GCxGC) combined with time-of-flight mass spectrometry (TOFMS). An intense "woody, cedarwood" odor was determined to be the most potent odorant in three of the four spicy fraction samples. This odor coincided with a complex region where between 8 and 13 compounds were coeluting in each of the four spicy fractions. The peak responsible was determined by (i) correlating peak areas with Charm values in eight hop samples and (ii) heart-cut multidimensional gas chromatography-olfactometry (MDGC-O). The compound responsible was tentatively identified as 14-hydroxy-beta-caryophyllene. Other important odorants identified were geraniol, linalool, beta-ionone, and eugenol.
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