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Humulus lupulus L. - Cannabaceae - hop, Hopfen
Perennial dioecious climbing herb, native from Europe to Central Asia, North America.
Value-determining components of hops are a resin fraction (15-25%) and an essential oil, the hop oil (0.3-1%).
http://de.wikipedia.org/wiki/Echter_Hopfen#Inhaltsstoffe
Humulone (α-lupulic acid) and Isohumulones are bitter-tasting compounds found in the resin of mature hops (Humulus lupulus). Those alpha acids collectively give beer its characteristic bitter flavor.
„During development from female inflorescences to cones, levels of α-acids, β-acids, desmethylxanthohumol, and xanthohumol gradually increased, while each hop variety exhibited individual accumulation rates. Furthermore, these compounds were present in leaves of fully grown hops as well. The study demonstrated that key compounds for flavor and potential beneficial health effects associated with beer not only reside in the glandular lupulin structures but also are distributed over various parts of the hop plant.“
[Formation and accumulation of α-acids, β-acids, desmethylxanthohumol, and xanthohumol during flowering of hops (Humulus lupulus L.)., De Keukeleire, J., Ooms, G., Heyerick, A., Roldan-Ruiz, I., Van Bockstaele, E., De Keukeleire, D., Journal of agricultural and food chemistry, Vol.51(15), 2003, 4436-4441]
β-Acids: „The follow-up products of lupulones, the hulupones and luputriones, own a particularly pleasant mild bitterness. But they are far less bitter, so that the bitter taste of beer is predominantly shaped by the humulone fraction.“
[Belitz, H. D., Grosch, W., Schieberle, P., Lehrbuch der lebensmittelchemie. Springer-Verlag, 2008, 925]
„The volatile constituents from several varieties of Hops have been investigated by the direct loading of fresh plant tissue through GC-MS. The Saaz variety was distinguished among the examined varieties by its high content of β-farnesene. Hallertau was characterized by a low content of myrcene and a high content of humulenes. Shinshu-wase differed in its high content of myrcene and its low content of humulenes. Northern Brewer was rather close to Hallertau, whereas Yakima appeared to be closely related to Shinshu-wase. The myrcene content of hop oil was observed to correlate competitively with the total amount of humulenes, caryophyllene, and farnesene. 2-Methylbutyl isobutyrate accumulates in company with myrcene.“
[The constituents of hops (Humulus lupulus L.). VII. The rapid analysis of volatile components., Naya, Y., Kotake, M., Bulletin of the Chemical Society of Japan, Vol.45(9), 1972, 2887-2891]
„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.“
[Comparison of the most odor-active compounds in fresh and dried hop cones (Humulus lupulus L. variety spalter select) based on GC-olfactometry and odor dilution techniques., Steinhaus, M., Schieberle, P., Journal of agricultural and food chemistry, Vol.48(5), 2000, 1776-1783]
„Hallertauer volatiles were dominated by sesquiterpene hydrocarbons (46.5-50.8%), mostly α-humulene (22.7-28.0%), (E)-caryophyllene (7.8-9.0%), and (E)-β-farnesene (4.6-5.7%), with lesser amounts of γ-muurolene (1.1-1.7%), δ-cadinene (1.9-2.3%), and γ-cadinene (1.1-1.5%). The monoterpene myrcene was also abundant (21.4-24.8%) as well as the oxygenated sesquiterpenoids caryophyllene oxide (2.2%) and humulene epoxide II (3.9-4.0%). Sesquiterpene hydrocarbons are often characterized as having spicy or woody odors (Jiroventz et al., 2006; Sant’Anna et al., 2007; Sádecká and Polovka, 2008) and Hallertauer hops have been described as earthy, spicy, and “noble” (Brew365).“
[Volatile components of aroma hops (Humulus lupulus L.) commonly used in beer brewing.,Nance, M.R., Setzer, W.N., Journal of Brewing and Distilling, 2(2), 2011, 16-22]
„Application of aroma extract dilution analysis on the volatiles isolated from a Bavarian Pilsner-type beer revealed 40 odor-active constituents in the flavor dilution (FD) factor range of 16−2048, among which ethyl octanoate, (E)-β-damascenone, 2- and 3-methylbutanoic acid, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone showed the highest FD factor of 2048. After quantitation of the 26 odorants showing FD factors ≥128 by stable isotope dilution analysis and determination of their odor thresholds in water, odor acitivity values (OAVs) were calculated. The results indicated ethanol, (E)-β-damascenone, (R)-linalool, acetaldehyde, and ethyl butanoate with the highest OAVs, followed by ethyl 2-methylpropanoate and ethyl 4-methylpentanoate, which was previously unknown in beer. Finally, the overall aroma of the beer could be mimicked for the first time by recombining 22 reference odorants in the same concentrations as they occurred in the beer using ethanol/water as the matrix.“
[Identification based on quantitative measurements and aroma recombination of the character impact odorants in a Bavarian Pilsner-type beer., Fritsch, H.T., Schieberle, P., Journal of agricultural and food chemistry, Vol.53(19), 2005, 7544-7551]
3-sulfanyl-4-methylpentan-1-ol and 3-sulfanyl-4-methylpentyl acetate have a grapefruit-like and/or rhubarb-like odor, similar to that of Sauvignon Blanc. They contribute to the specific odor of beers produced with Nelson Sauvin, a unique hop cultivar bred and grown in New Zealand.
[Identification and Characteristics of New Volatile Thiols Derived from the Hop (Humulus luplus L.) Cultivar Nelson Sauvin., Takoi, K., Degueil, M., Shinkaruk, S., Thibon, C., Maeda, K., Ito, K., Tominaga, T., Journal of agricultural and food chemistry, Vol.57(6), 2009, 2493-2502]
„The hop (Humulus lupulus L.), a component of beer, is a sedative plant whose pharmacological activity is principally due to its bitter resins, in particular to the α-acid degradation product 2-methyl-3-buten-2-ol. The mechanism of action of hop resin consists of raising the levels of the neurotransmitter γ-aminobutyric acid (GABA), an inhibitory neurotransmitter acting in the central nervous system (CNS).“
[The sedative effect of non-alcoholic beer in healthy female nurses., Franco, L., Sánchez, C., Bravo, R., Rodríguez, A.B., Barriga, C., Romero, E., Cubero, J., PloS one, Vol.7(7), 2012, e37290]
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0037290
Kohl, F.G., Die officinellen Pflanzen der Pharmacopoea Germanica, t.30 (1891-1895)
http://www.plantillustrations.org/species.php?id_species=539209