Humulus

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Humulus
Humulus.jpg
Common hop plant ( Humulus lupulus )
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Cannabaceae
Genus: Humulus
L.
Species

See text.

Synonyms [1]
  • Lupulus Mill.
  • Waldensia Lavy

Humulus, or hop, is a small genus of flowering plants in the family Cannabaceae. The hop is native to temperate regions of the Northern Hemisphere. Hops are the female flowers (seed cones, strobiles) of the hop species H. lupulus ; as a main flavor and aroma ingredient in many beer styles, H. lupulus is widely cultivated for use by the brewing industry.

Contents

Description

Although frequently referred to in American literature as the hops "vine", it is technically a bine; unlike vines, which use tendrils, suckers, and other appendages for attaching themselves, bines have stout stems with stiff hairs to aid in climbing. In British literature the term "vine" is generally reserved for the grape genus Vitis . Humulus is described as a twining perennial herbaceous plant which sends up new shoots in early spring and dies back to the cold-hardy rhizome in autumn. Hop shoots grow very rapidly, and at the peak of growth can grow 20 to 50 centimetres (8 to 20 inches) per week. Hop bines climb by wrapping clockwise (except for Humulus japonicus ) around anything within reach, and individual bines typically grow between 2 and 15 metres (7 and 50 feet) depending on what is available to grow on. The leaves are opposite, with a 7 to 12 cm (2+34 to 4+34 in) leafstalk and a heart-shaped, fan-lobed blade 12 to 25 cm (4+34 to 9+34 in) long and broad; the edges are coarsely toothed. When the hop bines run out of material to climb, horizontal shoots sprout between the leaves of the main stem to form a network of stems wound round each other. [2]

Male and female flowers of the hop plant are dioecious, developing on separate plants. Female plants, which produce the hop flowers used in brewing beer, are often propagated vegetatively and grown in the absence of male plants. This prevents pollination and the development of viable seeds, which are sometimes considered undesirable for brewing beer owing to the potential for off-flavors arising from the introduction of fatty acids from the seeds. [3]

The characteristic bitterness imparted by the addition of hops to the brewing process is mainly due to the presence of the bitter acids, which are prenylated acylphloroglucinol derivatives. [4] Bitter acids are divided into the alpha-acids, with humulone the major compound, and the beta-acids, with lupulone the major compound; [5] the alpha-acids isomerize during the brewing process to form iso-alpha acids, which themselves have a bitter taste. [6] [5] These hop acids are vinylogous acids, with acidic ring enols in conjugation with ring and substituent carbonyl groups. [7] [8] Plants in the genus Humulus produce terpenophenolic metabolites. [9] Hops also contain xanthohumol, a prenylated chalcone, and other compounds. [10]

Taxonomy

Humulus japonicus leaves hwansamdeonggul ip.JPG
Humulus japonicus leaves

As of October 2020, the following species were accepted: [1]

For brewers' hops, which are specific cultivars, and propagated by asexual reproduction, see the article, "List of hop varieties".

Uses

Hops are boiled with the wort in brewing beer and sometimes added post-ferment; they impart a bitterness, flavor, as well as aroma to the finished product. [5]

In pharmacy lupulus is the designation of hop. The dried catkins, commonly referred to as hop cones, of the female plant of H. lupulus are used to prepare infusion of hop, tincture of hop, and extract of hop. [11]

Some of the compounds hops contain are under preliminary research for their potential health properties. [10]

Related Research Articles

<span class="mw-page-title-main">Hops</span> Flower used to flavour beer and other beverages

Hops are the flowers of the hop plant Humulus lupulus, a member of the Cannabaceae family of flowering plants. They are used primarily as a bittering, flavouring, and stability agent in beer, to which, in addition to bitterness, they impart floral, fruity, or citrus flavours and aromas. Hops are also used for various purposes in other beverages and herbal medicine. The hops plants have separate female and male plants, and only female plants are used for commercial production. The hop plant is a vigorous, climbing, herbaceous perennial, usually trained to grow up strings in a field called a hopfield, hop garden, or hop yard when grown commercially. Many different varieties of hops are grown by farmers around the world, with different types used for particular styles of beer.

<i>Humulus lupulus</i> Species of flowering plant

Humulus lupulus, the common hop or hops, is a species of flowering plant in the hemp family, Cannabaceae. It is a perennial, herbaceous climbing plant which sends up new shoots in early spring and dies back to a cold-hardy rhizome in autumn. It is dioecious and native to West Asia, Europe and North America.

<span class="mw-page-title-main">Myrcene</span> Chemical compound

Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils. It is produced mainly semi-synthetically from Myrcia, from which it gets its name. It is an intermediate in the production of several fragrances. α-Myrcene is the name for the isomer 2-methyl-6-methylene-1,7-octadiene, which has not been found in nature.

<span class="mw-page-title-main">Humulene</span> Chemical compound

Humulene, also known as α-humulene or α-caryophyllene, is a naturally occurring monocyclic sesquiterpene (C15H24), containing an 11-membered ring and consisting of 3 isoprene units containing three nonconjugated C=C double bonds, two of them being triply substituted and one being doubly substituted. It was first found in the essential oils of Humulus lupulus (hops), from which it derives its name. Humulene is an isomer of β-caryophyllene, and the two are often found together as a mixture in many aromatic plants.

<span class="mw-page-title-main">Ocimene</span> Chemical compound

Ocimenes are a group of isomeric hydrocarbons. The ocimenes are monoterpenes found within a variety of plants and fruits. α-Ocimene and the two β-ocimenes differ in the position of the isolated double bond: it is terminal in the alpha isomer. α-Ocimene is cis-3,7-dimethyl-1,3,7-octatriene. β-Ocimene is trans-3,7-dimethyl-1,3,6-octatriene. β-Ocimene exists in two stereoisomeric forms, cis and trans, with respect to the central double bond. The ocimenes are often found naturally as mixtures of the various forms. The mixture, as well as the pure compounds, are oils with a pleasant odor. They are used in perfumery for their sweet herbal scent, and are believed to act as plant defense and have anti-fungal properties. Like the related acyclic terpene myrcene, ocimenes are unstable in air. Like other terpenes, the ocimenes are nearly insoluble in water, but soluble in common organic solvents.

β-Pinene Chemical compound

β-Pinene is a monoterpene, an organic compound found in plants. It is one of the two isomers of pinene, the other being α-pinene. It is a colorless liquid soluble in alcohol, but not water. It has a woody-green pine-like smell.

<i>Humulus japonicus</i> Species of flowering plant

Humulus japonicus, known as Japanese hops, is an ornamental plant in the family Cannabaceae. Some authorities have it as a synonym of Humulus scandens.

<span class="mw-page-title-main">Alpha acid</span>

Alpha acids are a class of chemical compounds primarily of importance to the production of beer. They are found in the resin glands of the flowers of the hop plant and are the source of hop bitterness.

<span class="mw-page-title-main">Isohumulone</span> Chemical compound

Isohumulones are chemical compounds that contribute to the bitter taste of beer and are in the class of compounds known as iso-alpha acids. They are found in hops.

<span class="mw-page-title-main">Cannabaceae</span> Family of flowering plants comprising hops, hemps, and hackberries

Cannabaceae is a small family of flowering plants, known as the hemp family. As now circumscribed, the family includes about 170 species grouped in about 11 genera, including Cannabis (hemp), Humulus (hops) and Celtis (hackberries). Celtis is by far the largest genus, containing about 100 species.

<span class="mw-page-title-main">Prenylflavonoid</span>

Prenylated flavonoids or prenylflavonoids are a sub-class of flavonoids. They are widely distributed throughout the plant kingdom. Some are known to have phytoestrogenic or antioxidant properties. They are given in the list of adaptogens in herbalism. Chemically they have a prenyl group attached to their flavonoid backbone. It is usually assumed that the addition of hydrophobic prenyl groups facilitate attachment to cell membranes. Prenylation may increase the potential activity of its original flavonoid.

<span class="mw-page-title-main">Xanthohumol</span> Chemical compound

Xanthohumol is a natural product found in the female inflorescences of Humulus lupulus, also known as hops. This compound is also found in beer and belongs to a class of compounds that contribute to the bitterness and flavor of hops. Xanthohumol is a prenylated chalconoid, biosynthesized by a type III polyketide synthase (PKS) and subsequent modifying enzymes.

When drinking beer, there are many factors to be considered. Principal among them are bitterness, the variety of flavours present in the beverage and their intensity, alcohol content, and colour. Standards for those characteristics allow a more objective and uniform determination to be made on the overall qualities of any beer.

<span class="mw-page-title-main">Humulone</span> Chemical compound

Humulone, a vinylogous type of organic acid, is a bitter-tasting chemical compound found in the resin of mature hops. Humulone is a prevalent member of the class of compounds known as alpha acids, which collectively give hopped beer its characteristic bitter flavor.

<span class="mw-page-title-main">8-Prenylnaringenin</span> Chemical compound

8-Prenylnaringenin (8-PN; also known as flavaprenin, (S)-8-dimethylallylnaringenin, hopein, or sophoraflavanone B) is a prenylflavonoid phytoestrogen. It is reported to be the most estrogenic phytoestrogen known. The compound is equipotent at the two forms of estrogen receptors, ERα and ERβ, and it acts as a full agonist of ERα. Its effects are similar to those of estradiol, but it is considerably less potent in comparison.

<span class="mw-page-title-main">Isoxanthohumol</span> Chemical compound

Isoxanthohumol is a prenylflavonoid, and it is a phytoestrogen. It is abbreviated as IX or IXN.

<span class="mw-page-title-main">Lupulone</span> Chemical compound

Lupulone is an organic chemical compound with the molecular formula C26H38O4 and an appearance of a yellow powder which was historically used in beer brewing.

<span class="mw-page-title-main">Beer chemistry</span> Brewery science and beer chemical composition

The chemical compounds in beer give it a distinctive taste, smell and appearance. The majority of compounds in beer come from the metabolic activities of plants and yeast and so are covered by the fields of biochemistry and organic chemistry. The main exception is that beer contains over 90% water and the mineral ions in the water (hardness) can have a significant effect upon the taste.

<span class="mw-page-title-main">Hop production in the United States</span>

The United States of America is the world's largest producer of hops, the flowers of female Humulus lupulus plants. The primary use of hops grown in the United States is in brewing. In 2019, the U.S. accounted for 40% of world hop production and 39% of world hop acreage.

References

  1. 1 2 "Humulus L." Plants of the World Online. Board of Trustees of the Royal Botanic Gardens, Kew. 2017. Retrieved 14 October 2020.
  2. Brickell, Christopher, ed. (2008). The Royal Horticultural Society A-Z Encyclopedia of Garden Plants. United Kingdom: Dorling Kindersley. p. 550. ISBN   9781405332965.
  3. Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries. Economic Plants and their Diseases, Pests and Weeds. Humulus lupulus. Archived 2012-03-10 at the Wayback Machine
  4. Verzele, M.; De Keukeleire, D. (1991). Chemistry and analysis of hop and beer bitter acids. New York: Elsevier. ISBN   978-0-444-88165-6.
  5. 1 2 3 Almaguer, Cynthia; Schönberger, Christina; Gastl, Martina; Arendt, Elke K.; Becker, Thomas (September 2014). "Humulus lupulus - a story that begs to be told. A review: Humulus lupulus - a story that begs to be told". Journal of the Institute of Brewing. doi: 10.1002/jib.160 .
  6. Jaskula, Barbara; Kafarski, Pawel; Aerts, Guido; De Cooman, Luc (August 2008). "A Kinetic Study on the Isomerization of Hop α-Acids". Journal of Agricultural and Food Chemistry. 56 (15): 6408–6415. doi:10.1021/jf8004965. PMID   18598038.
  7. Urban, Jan; Dahlberg, Clinton J.; Carroll, Brian J.; Kaminsky, Werner (28 January 2013). "Absolute Configuration of Beer′s Bitter Compounds". Angewandte Chemie International Edition. 52 (5): 1553–1555. doi:10.1002/anie.201208450. PMC   3563212 . PMID   23239507.
  8. De Keukeleire, Denis (February 2000). "Fundamentals of beer and hop chemistry". Química Nova. 23 (1): 108–112. doi: 10.1590/S0100-40422000000100019 .
  9. Page, Jonathan E.; Nagel, Jana (2006). "Biosynthesis of terpenophenolic metabolites in hop and cannabis". Recent Advances in Phytochemistry. Vol. 40. pp. 179–210. doi:10.1016/S0079-9920(06)80042-0. ISBN   9780080451251.
  10. 1 2 Stevens, Jan F; Page, Jonathan E (May 2004). "Xanthohumol and related prenylflavonoids from hops and beer: to your good health!". Phytochemistry. 65 (10): 1317–1330. Bibcode:2004PChem..65.1317S. doi:10.1016/j.phytochem.2004.04.025. PMID   15231405.
  11. Reynolds, Francis J., ed. (1921). "Hop"  . Collier's New Encyclopedia . New York: P. F. Collier & Son Company.