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Hops are the
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s (also called seed cones or strobiles) of the hop plant ''
Humulus lupulus ''Humulus lupulus'', the common hop or hops, is a species of flowering plant in the hemp family Cannabinaceae, native to Europe, western Asia and North America. It is a perennial, herbaceous climbing plant which sends up new shoots in early spr ...
'', a member of the
Cannabaceae Cannabaceae is a small family (biology), family of flowering plants, known as the hemp family. As now Circumscription (taxonomy), circumscribed, the family includes about 170 species grouped in about 11 genera, including ''Cannabis'' (hemp), ''H ...
family of flowering plants. They are used primarily as a bittering, flavouring, and stability agent in
beer Beer is one of the oldest and the most widely consumed type of alcoholic drink in the world, and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from ce ...
, 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 Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern remed ...
. 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 Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of t ...
perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
, usually trained to grow up strings in a field called a hopfield, hop garden (in the South of England), or hop yard (in the
West Country The West Country (occasionally Westcountry) is a loosely defined area of South West England, usually taken to include all, some, or parts of the counties of Cornwall, Devon, Dorset, Somerset, Bristol, and, less commonly, Wiltshire, Gloucesters ...
and United States) when grown commercially. Many different varieties of hops are grown by farmers around the world, with different types used for particular styles of beer. The first documented use of hops in beer is from the 9th century, though
Hildegard of Bingen Hildegard of Bingen (german: Hildegard von Bingen; la, Hildegardis Bingensis; 17 September 1179), also known as Saint Hildegard and the Sibyl of the Rhine, was a German Benedictine abbess and polymath active as a writer, composer, philosopher ...
, 300 years later, is often cited as the earliest documented source. Before this period, brewers used a "
gruit Gruit (alternately grut or gruyt) is a herb mixture used for bittering and flavouring beer, popular before the extensive use of hops. The terms gruit and grut ale may also refer to the beverage produced using gruit. Historically, gruit is the te ...
", composed of a wide variety of bitter herbs and flowers, including
dandelion ''Taraxacum'' () is a large genus of flowering plants in the family Asteraceae, which consists of species commonly known as dandelions. The scientific and hobby study of the genus is known as taraxacology. The genus is native to Eurasia and Nor ...
,
burdock ''Arctium'' is a genus of biennial plants commonly known as burdock, family Asteraceae. Native to Europe and Asia, several species have been widely introduced worldwide. Burdock's clinging properties, in addition to providing an excellent mecha ...
root, marigold, horehound (the old German name for horehound, ''Berghopfen'', means "mountain hops"),
ground ivy ''Glechoma hederacea'' is an aromatic, perennial, evergreen creeper of the mint family Lamiaceae. It is commonly known as ground-ivy, gill-over-the-ground, creeping charlie, alehoof, tunhoof, catsfoot, field balm, and run-away-robin. It is als ...
, and heather. Early documents include mention of a hop garden in the will of
Charlemagne Charlemagne ( , ) or Charles the Great ( la, Carolus Magnus; german: Karl der Große; 2 April 747 – 28 January 814), a member of the Carolingian dynasty, was King of the Franks from 768, King of the Lombards from 774, and the first Holy ...
's father,
Pepin the Short the Short (french: Pépin le Bref; – 24 September 768), also called the Younger (german: Pippin der Jüngere), was King of the Franks from 751 until his death in 768. He was the first Carolingian to become king. The younger was the son of ...
. Hops are also used in brewing for their
antibacterial An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
effect over less desirable
microorganisms A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
and for purported benefits including balancing the sweetness of the
malt Malt is germinated cereal grain that has been dried in a process known as " malting". The grain is made to germinate by soaking in water and is then halted from germinating further by drying with hot air. Malted grain is used to make beer, wh ...
with bitterness and a variety of flavours and aromas. Historically, traditional herb combinations for beers were believed to have been abandoned when beers made with hops were noticed to be less prone to spoilage.


History

The first documented hop cultivation was in 736, in the
Hallertau The Hallertau or Holledau is an area in Bavaria, Germany. With an area of 178 km², it is listed as the largest continuous hop-planting area in the world.Bentley, James; Catling, Christopher; & Locke, Tim (1994). ''Munich and Bavaria''. Chicago: ...
region of present-day Germany, although the first mention of the use of hops in brewing in that country was 1079. However, in a will of
Pepin the Short the Short (french: Pépin le Bref; – 24 September 768), also called the Younger (german: Pippin der Jüngere), was King of the Franks from 751 until his death in 768. He was the first Carolingian to become king. The younger was the son of ...
, the father of
Charlemagne Charlemagne ( , ) or Charles the Great ( la, Carolus Magnus; german: Karl der Große; 2 April 747 – 28 January 814), a member of the Carolingian dynasty, was King of the Franks from 768, King of the Lombards from 774, and the first Holy ...
, hop gardens were left to the Cloister of Saint-Denis in 768. Not until the 13th century did hops begin to start threatening the use of
gruit Gruit (alternately grut or gruyt) is a herb mixture used for bittering and flavouring beer, popular before the extensive use of hops. The terms gruit and grut ale may also refer to the beverage produced using gruit. Historically, gruit is the te ...
for flavouring. Gruit was used when the nobility levied taxes on hops. Whichever was taxed made the brewer then quickly switch to the other. In Britain, hopped beer was first imported from Holland around 1400, yet hops were condemned as late as 1519 as a "wicked and pernicious weed". In 1471,
Norwich Norwich () is a cathedral city and district of Norfolk, England, of which it is the county town. Norwich is by the River Wensum, about north-east of London, north of Ipswich and east of Peterborough. As the seat of the See of Norwich, with ...
, England, banned use of the plant in the brewing of
ale Ale is a Type of beer, type of beer brewed using a Warm fermentation, warm fermentation method, resulting in a sweet, full-bodied and fruity taste. Historically, the term referred to a drink brewed without hops. As with most beers, ale typicall ...
("beer" was the name for fermented malt liquors bittered with hops; only in recent times are the words often used as synonyms). In Germany, using hops was also a religious and political choice in the early 16th century. There was no tax on hops to be paid to the Catholic church, unlike on gruit. For this reason the Protestants preferred hopped beer. Hops used in England were imported from France, Holland and Germany and were subject to
import duty A tariff is a tax imposed by the government of a country or by a supranational union on imports or exports of goods. Besides being a source of revenue for the government, import duties can also be a form of regulation of foreign trade and polic ...
; it was not until 1524 that hops were first grown in the southeast of England (
Kent Kent is a county in South East England and one of the home counties. It borders Greater London to the north-west, Surrey to the west and East Sussex to the south-west, and Essex to the north across the estuary of the River Thames; it faces ...
), when they were introduced as an agricultural crop by
Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () Dutch may also refer to: Places * Dutch, West Virginia, a community in the United States * Pennsylvania Dutch Country People E ...
farmers. Consequently many words used in the hop industry derive from the
Dutch language Dutch ( ) is a West Germanic language spoken by about 25 million people as a first language and 5 million as a second language. It is the third most widely spoken Germanic language The Germanic languages are a branch of the Indo-Europea ...
. Hops were then grown as far north as
Aberdeen Aberdeen (; sco, Aiberdeen ; gd, Obar Dheathain ; la, Aberdonia) is a city in North East Scotland, and is the third most populous city in the country. Aberdeen is one of Scotland's 32 local government council areas (as Aberdeen City), and ...
, near breweries for convenience of infrastructure. According to
Thomas Tusser Thomas Tusser (c. 15243 May 1580) was an English poet and farmer, best known for his instructional poem ''Five Hundred Points of Good Husbandry'', an expanded version of his original title, ''A Hundreth Good Pointes of Husbandrie'', first publishe ...
's 1557 ''Five Hundred Points of Good Husbandry'':
"The hop for his profit I thus do exalt,
It strengtheneth drink and it flavoureth malt;
And being well-brewed long kept it will last,
And drawing abide, if ye draw not too fast."
In England there were many complaints over the quality of imported hops, the sacks of which were often contaminated by stalks, sand or straw to increase their weight. As a result, in 1603, King
James I James I may refer to: People *James I of Aragon (1208–1276) *James I of Sicily or James II of Aragon (1267–1327) *James I, Count of La Marche (1319–1362), Count of Ponthieu *James I, Count of Urgell (1321–1347) *James I of Cyprus (1334–13 ...
approved an Act of Parliament banning the practice by which "the Subjects of this Realm have been of late years abused &c. to the Value of £20,000 yearly, besides the Danger of their Healths". Hop cultivation was begun in the present-day United States in 1629 by English and Dutch farmers. Before
prohibition Prohibition is the act or practice of forbidding something by law; more particularly the term refers to the banning of the manufacture, storage (whether in barrels or in bottles), transportation, sale, possession, and consumption of alcoholic ...
, cultivation was mainly centred around New York, California, Oregon, and
Washington state Washington (), officially the State of Washington, is a state in the Pacific Northwest region of the Western United States. Named for George Washington—the first U.S. president—the state was formed from the western part of the Washington ...
. Problems with
powdery mildew Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant diseases to identify, as ...
and
downy mildew Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to the Peronosporaceae family. In commercial agriculture, they are a particular problem for growers of crucif ...
devastated New York's production by the 1920s, and California only produces hops on a small scale.


World production

Hops production is concentrated in moist temperate climates, with much of the world's production occurring near the
48th parallel north The 48th parallel north is a circle of latitude that is 48 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean. In Canada the parallel forms part of the border betwee ...
. Hop plants prefer the same soils as potatoes and the leading potato-growing states in the United States are also major hops-producing areas; however, not all potato-growing areas can produce good hops naturally: soils in the
Maritime Provinces The Maritimes, also called the Maritime provinces, is a region of Eastern Canada consisting of three provinces: New Brunswick, Nova Scotia, and Prince Edward Island. The Maritimes had a population of 1,899,324 in 2021, which makes up 5.1% of Ca ...
of Canada, for example, lack the
boron Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the ''boron group'' it has th ...
that hops prefer. Historically, hops were not grown in Ireland, but were imported from England. In 1752 more than 500
ton Ton is the name of any one of several units of measure. It has a long history and has acquired several meanings and uses. Mainly it describes units of weight. Confusion can arise because ''ton'' can mean * the long ton, which is 2,240 pounds ...
s of English hops were imported through Dublin alone. Important production centres today are the
Hallertau The Hallertau or Holledau is an area in Bavaria, Germany. With an area of 178 km², it is listed as the largest continuous hop-planting area in the world.Bentley, James; Catling, Christopher; & Locke, Tim (1994). ''Munich and Bavaria''. Chicago: ...
in Germany, the
Žatec Žatec (; german: Saaz) is a town in Louny District in the Ústí nad Labem Region of the Czech Republic. It has about 19,000 inhabitants. It lies on the Ohře river. The town centre is well preserved and is protected by law as an urban monument ...
(
Saaz Saaz may refer to: *Saaz, the former German name of Žatec, a town in the Czech Republic **Saaz hops, a hop variety used in production of pilsener style beer **DSV Saaz, a former football club in Žatec * ''Saaz'' (film), a 1998 Indian film * Saaz ...
) in the
Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...
, the
Yakima Yakima ( or ) is a city in and the county seat of Yakima County, Washington, and the state's 11th-largest city by population. As of the 2020 census, the city had a total population of 96,968 and a metropolitan population of 256,728. The uninco ...
(
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...
) and Willamette (Oregon) valleys, and western Canyon County, Idaho (including the communities of
Parma Parma (; egl, Pärma, ) is a city in the northern Italian region of Emilia-Romagna known for its architecture, Giuseppe Verdi, music, art, prosciutto (ham), Parmigiano-Reggiano, cheese and surrounding countryside. With a population of 198,292 ...
, Wilder, Greenleaf, and
Notus In ancient Greek religion and myth, the Anemoi (Greek: , 'Winds') were wind gods who were each ascribed a cardinal direction from which their respective winds came (see Classical compass winds), and were each associated with various seasons and ...
). The principal production centres in the UK are in
Kent Kent is a county in South East England and one of the home counties. It borders Greater London to the north-west, Surrey to the west and East Sussex to the south-west, and Essex to the north across the estuary of the River Thames; it faces ...
(which produces Kent Goldings hops),
Herefordshire Herefordshire () is a county in the West Midlands of England, governed by Herefordshire Council. It is bordered by Shropshire to the north, Worcestershire to the east, Gloucestershire to the south-east, and the Welsh counties of Monmouthshire ...
, and
Worcestershire Worcestershire ( , ; written abbreviation: Worcs) is a county in the West Midlands of England. The area that is now Worcestershire was absorbed into the unified Kingdom of England in 927, at which time it was constituted as a county (see His ...
. Essentially all of the harvested hops are used in beer making.


Cultivation and harvest

Although hops are grown in most of the continental United States and Canada, cultivation of hops for commercial production requires a particular environment. As hops are a climbing plant, they are trained to grow up trellises made from strings or wires that support the plants and allow them significantly greater growth with the same sunlight profile. In this way, energy that would have been required to build structural cells is also freed for crop growth. The hop plant's
reproduction Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual or ...
method is that male and female flowers develop on separate plants, although occasionally a fertile individual will develop which contains both male and female flowers. Because pollinated seeds are undesirable for brewing beer, only female plants are grown in hop fields, thus preventing pollination. Female plants are propagated
vegetatively Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or spec ...
, and male plants are culled if plants are grown from seeds. Hop plants are planted in rows about apart. Each spring, the roots send forth new bines that are started up strings from the ground to an overhead trellis. The cones grow high on the bine, and in the past, these cones were picked by hand. Harvesting of hops became much more efficient with the invention of the mechanical hops separator, patented by
Emil Clemens Horst Emil Clemens Horst (18 March 1867 – 24 May 1940) was a major figure in the cultivation, harvest and sale of hops in the United States. The founder of the Horst Company. He invented the mechanical hops separator in 1909 and was the largest hop gr ...
in 1909. Hops are harvested at the end of summer. The are cut down, separated, and then dried in an
oast house An oast, oast house or hop kiln is a building designed for kilning (drying) hops as part of the brewing process. They can be found in most hop-growing (and former hop-growing) areas and are often good examples of vernacular architecture. Many re ...
to reduce moisture content. To be dried, the hops are spread out on the upper floor of the oast house and heated by heating units on the lower floor. The dried hops are then compressed into bales by a
baler A baler or hay baler is a piece of farm machinery used to compress a cut and raked crop (such as hay, cotton, flax straw, salt marsh hay, or silage) into compact bales that are easy to handle, transport, and store. Often, bales are configured ...
. Hop cones contain different oils, such as lupulin, a yellowish, waxy substance, an
oleoresin Oleoresins are semi-solid extracts composed of resin and essential or fatty oil, obtained by evaporation of the solvents used for their production. The oleoresin of conifers is known as crude turpentine or gum turpentine, which consists of oil of ...
, that imparts flavour and aroma to beer. Lupulin contains
lupulone Lupulone is an organic chemical compound with the molecular formula C26 H38 O4 and an appearance of a yellow powder which was historically used in beer brewing. However, recent studies have revealed numerous antibacterial and anti-cancer abilitie ...
and
humulone Humulone (α-lupulic acid), a vinylogous type of organic acid, is a bitter-tasting chemical compound found in the resin of mature hops (''Humulus lupulus''). Humulone is a prevalent member of the class of compounds known as alpha acids, which c ...
, which possess antibiotic properties, suppressing bacterial growth favoring brewer's yeast to grow. After lupulin has been extracted in the brewing process the papery cones are discarded.


Migrant labor and social impact

The need for massed labor at harvest time meant hop-growing had a big social impact. Around the world, the labor-intensive harvesting work involved large numbers of migrant workers who would travel for the annual hop harvest. Whole families would participate and live in hoppers' huts, with even the smallest children helping in the fields. The final chapters of
W. Somerset Maugham William Somerset Maugham ( ; 25 January 1874 – 16 December 1965) was an English writer, known for his plays, novels and short stories. Born in Paris, where he spent his first ten years, Maugham was schooled in England and went to a German un ...
's ''
Of Human Bondage ''Of Human Bondage'' is a 1915 novel by W. Somerset Maugham. The novel is generally agreed to be Maugham's masterpiece and to be strongly autobiographical in nature, although he stated, "This is a novel, not an autobiography; though much in i ...
'' and a large part of
George Orwell Eric Arthur Blair (25 June 1903 – 21 January 1950), better known by his pen name George Orwell, was an English novelist, essayist, journalist, and critic. His work is characterised by lucid prose, social criticism, opposition to totalitar ...
's ''
A Clergyman's Daughter ''A Clergyman's Daughter'' is a 1935 novel by English author George Orwell. It tells the story of Dorothy Hare, the clergyman's daughter of the title, whose life is turned upside down when she suffers an attack of amnesia. It is Orwell's most f ...
'' contain a vivid description of London families participating in this annual hops harvest. In England, many of those picking hops in
Kent Kent is a county in South East England and one of the home counties. It borders Greater London to the north-west, Surrey to the west and East Sussex to the south-west, and Essex to the north across the estuary of the River Thames; it faces ...
were from eastern areas of London. This provided a break from urban conditions that was spent in the countryside. People also came from Birmingham and other Midlands cities to pick hops in the
Malvern Malvern or Malverne may refer to: Places Australia * Malvern, South Australia, a suburb of Adelaide * Malvern, Victoria, a suburb of Melbourne * City of Malvern, a former local government area near Melbourne * Electoral district of Malvern, an e ...
area of Worcestershire. Some photographs have been preserved. The often-appalling living conditions endured by hop pickers during the harvest became a matter of scandal across Kent and other hop-growing counties. Eventually, the Rev.
John Young Stratton The Rev. John Young Stratton (1829/30 – 30 March 1905) was an author, essayist, social reformer, campaigner against rural poverty, and Rector of Ditton, Kent for 48 years. He is remembered mainly for his tireless campaigning to improve the live ...
, Rector of Ditton, Kent, began to gather support for reform, resulting in 1866 in the formation of the Society for the Employment and Improved Lodging of Hop Pickers. Particularly in Kent, because of a shortage of small-denomination coin of the realm, many growers issued their own currency to those doing the labor. In some cases, the coins issued were adorned with fanciful hops images, making them quite beautiful. In the United States,
Prohibition Prohibition is the act or practice of forbidding something by law; more particularly the term refers to the banning of the manufacture, storage (whether in barrels or in bottles), transportation, sale, possession, and consumption of alcoholic ...
had a serious adverse effect on hops production, but remnants of this significant industry in the western states are still noticeable in the form of old hop kilns that survive throughout
Sonoma County, California Sonoma County () is a county (United States), county located in the U.S. state of California. As of the 2020 United States Census, its population was 488,863. Its county seat and largest city is Santa Rosa, California, Santa Rosa. It is to the n ...
, among others. Florian Dauenhauer, of
Santa Rosa Santa Rosa is the Italian, Portuguese and Spanish name for Saint Rose. Santa Rosa may also refer to: Places Argentina *Santa Rosa, Mendoza, a city * Santa Rosa, Tinogasta, Catamarca * Santa Rosa, Valle Viejo, Catamarca *Santa Rosa, La Pampa * Sa ...
in Sonoma County, became a manufacturer of hop-harvesting machines in 1940, in part because of the hop industry's importance to the county. This mechanization helped destroy the local industry by enabling large-scale mechanized production, which moved to larger farms in other areas. Dauenhauer Manufacturing Company remains a current producer of hop harvesting machines.


Chemical composition

In addition to water, cellulose, and various proteins, the chemical composition of hops consists of compounds important for imparting character to beer.


Alpha acids

Probably the most important chemical compound within hops are the alpha acids or
humulone Humulone (α-lupulic acid), a vinylogous type of organic acid, is a bitter-tasting chemical compound found in the resin of mature hops (''Humulus lupulus''). Humulone is a prevalent member of the class of compounds known as alpha acids, which c ...
s. During wort boiling, the humulones are thermally isomerized into iso-alpha acids or ''isohumulones'', which are responsible for the bitter taste of beer.


Beta acids

Hops contain beta acids or
lupulone Lupulone is an organic chemical compound with the molecular formula C26 H38 O4 and an appearance of a yellow powder which was historically used in beer brewing. However, recent studies have revealed numerous antibacterial and anti-cancer abilitie ...
s. These are desirable for their aroma contributions to beer.


Essential oils

The main components of hops essential oils are
terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ar ...
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
s consisting of
myrcene 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. ...
,
humulene 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 be ...
and
caryophyllene Caryophyllene (), more formally (−)-β-caryophyllene, (BCP), is a natural bicyclic sesquiterpene that is a constituent of many essential oils, especially clove oil, the oil from the stems and flowers of '' Syzygium aromaticum'' (cloves), the ess ...
. Myrcene is responsible for the pungent smell of fresh hops. Humulene and its oxidative reaction products may give beer its prominent hop aroma. Together, myrcene, humulene, and caryophyllene represent 80 to 90% of the total hops essential oil.


Flavonoids

Xanthohumol 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. Xanthohum ...
is the principal
flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...
in hops. The other well-studied
prenylflavonoid 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 herbali ...
s are 8-Prenylnaringenin and
isoxanthohumol Isoxanthohumol is a prenylflavonoid, and it is a phytoestrogen. It is abbreviated as IX or IXN. 8-Prenylnaringenin can be produced from isoxanthohumol by flora in the human intestine, and by fungi in cell cultures. This prenylflavonoid is found ...
. Xanthohumol is under
basic research Basic research, also called pure research or fundamental research, is a type of scientific research with the aim of improving scientific theories for better understanding and prediction of natural or other phenomena. In contrast, applied resear ...
for its potential properties, while 8-prenylnaringenin is a potent
phytoestrogen A phytoestrogen is a plant-derived xenoestrogen (see estrogen) not generated within the endocrine system, but consumed by eating plants or manufactured foods. Also called a "dietary estrogen", it is a diverse group of naturally occurring nonstero ...
.


Brewing

Hops are usually dried in an
oast house An oast, oast house or hop kiln is a building designed for kilning (drying) hops as part of the brewing process. They can be found in most hop-growing (and former hop-growing) areas and are often good examples of vernacular architecture. Many re ...
before they are used in the brewing process. Undried or "wet" hops are sometimes (since c. 1990) used. The
wort Wort () is the liquid extracted from the mashing process during the brewing of beer or whisky. Wort contains the sugars, the most important being maltose and maltotriose, that will be fermented by the brewing yeast to produce alcohol. Wort ...
(sugar-rich liquid produced from
malt Malt is germinated cereal grain that has been dried in a process known as " malting". The grain is made to germinate by soaking in water and is then halted from germinating further by drying with hot air. Malted grain is used to make beer, wh ...
) is boiled with hops before it is cooled down and
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...
is added, to start
fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...
. The effect of hops on the finished beer varies by type and use, though there are two main hop types: bittering and aroma. Bittering hops have higher concentrations of alpha acids, and are responsible for the large majority of the bitter flavour of a beer. European (so-called "noble") hops typically average 5–9% alpha acids by weight (AABW), and the newer American
cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
s typically range from 8–19% AABW. Aroma hops usually have a lower concentration of alpha acids (~5%) and are the primary contributors of hop aroma and (nonbitter) flavour. Bittering hops are boiled for a longer period of time, typically 60–90 minutes, and often have inferior aromatic properties, as the aromatic compounds evaporate during the boil. The degree of bitterness imparted by hops depends on the degree to which
alpha acid Alpha acids (α 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. Alpha acids may be isomerized ...
s are
isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...
ized during the boil, and the impact of a given amount of hops is specified in
International Bitterness Units 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 o ...
. On the other hand, unboiled hops are only mildly
bitter Bitter may refer to: Common uses * Resentment, negative emotion or attitude, similar to being jaded, cynical or otherwise negatively affected by experience * Bitter (taste), one of the five basic tastes Books * '' Bitter (novel)'', a 2022 nove ...
. Aroma hops are typically added to the wort later to prevent the evaporation of the essential oils, to impart "hop taste" (if during the final 30 minutes of boil) or "hop aroma" (if during the final 10 minutes, or less, of boil). Aroma hops are often added after the wort has cooled and while the beer ferments, a technique known as "dry hopping", which contributes to the hop aroma.
Farnesene The term farnesene refers to a set of six closely related chemical compounds which all are sesquiterpenes. α-Farnesene and β-farnesene are isomers, differing by the location of one double bond. α-Farnesene is 3,7,11-trimethyl-1,3,6,10-dodecat ...
is a major component in some hops. The composition of hop essential oils can differ between varieties and between years in the same variety, having a significant influence on flavour and aroma. Today, a substantial amount of "dual-use" hops are used, as well. These have high concentrations of alpha acids and good aromatic properties. These can be added to the boil at any time, depending on the desired effect. Hop acids also contribute to and stabilize the foam qualities of beer. Flavours and aromas are described appreciatively using terms which include "grassy", "floral", "citrus", "spicy", "piney", "lemony", "grapefruit", and "earthy". Many
pale lager Pale lager is a very pale-to-golden-colored lager beer with a well- attenuated body and a varying degree of noble hop bitterness. The brewing process for this beer developed in the mid-19th century, when Gabriel Sedlmayr took pale ale brewing ...
s have fairly low hop influence, while lagers marketed as
Pilsener Pilsner (also pilsener or simply pils) is a type of pale lager. It takes its name from the Bohemian city of Plzeň (german: Pilsen), where the world's first pale lager (now known as Pilsner Urquell) was produced in 1842 by Pilsner Urquell Brewe ...
or brewed in the Czech Republic may have noticeable noble hop aroma. Certain
ale Ale is a Type of beer, type of beer brewed using a Warm fermentation, warm fermentation method, resulting in a sweet, full-bodied and fruity taste. Historically, the term referred to a drink brewed without hops. As with most beers, ale typicall ...
s (particularly the highly hopped style known as India Pale Ale, or IPA) can have high levels of hop bitterness. Brewers may use software tools to control the bittering levels in the boil and adjust recipes to account for a change in the hop bill or seasonal variations in the crop that may lead to the need to compensate for a difference in alpha acid contribution. Data may be shared with other brewers via
BeerXML BeerXML is a free, fully defined XML data description standard designed for the exchange of beer brewing recipes and other brewing data. Tables of recipes as well as other records such as hop schedules and malt bills can be represented using B ...
allowing the reproduction of a recipe allowing for differences in hop availability.


Varieties


Breeding programmes

There are many different varieties of hops used in brewing today. Historically, hops varieties were identified by geography (such as Hallertau, Spalt, and Tettnang from Germany), by the farmer who is recognized as first cultivating them (such as Goldings or Fuggles from England), or by their growing habit (e.g., Oregon Cluster). Around 1900, a number of institutions began to experiment with breeding specific hop varieties. The breeding program at
Wye College bio sciences -> social sciences -> business school Pictures of OLT, Old Hall,Cloister, Parlour --> The College of St Gregory and St Martin at Wye, commonly known as Wye College, was an education and research institution in the village of Wye ...
in
Wye, Kent Wye is a village in Kent, England, from Ashford and from Canterbury. It is the main settlement in the civil parish of Wye with Hinxhill. Hop varieties including Wye Challenger were bred at Wye College and named for the village. In 2013, ''S ...
, was started in 1904 and rose to prominence through the work of Prof.
E. S. Salmon Ernest Stanley Salmon (1 June 1871 – 12 October 1959) was a British mycologist and plant pathologist best known for his work in breeding new varieties of hops. Salmon crossed a wild Manitoban hop with cultivated English stock to create hybri ...
. Salmon released Brewer's Gold and Brewer's Favorite for commercial cultivation in 1934, and went on to release more than two dozen new cultivars before his death in 1959. Brewer's Gold has become the ancestor of the bulk of new hop releases around the world since its release. Wye College continued its breeding program and again received attention in the 1970s, when Dr. Ray A. Neve released Wye
Target Target may refer to: Physical items * Shooting target, used in marksmanship training and various shooting sports ** Bullseye (target), the goal one for which one aims in many of these sports ** Aiming point, in field artillery, fi ...
, Wye
Challenger Challenger, Challengers, or The Challengers may refer to: Entertainment Comics and manga * Challenger (character), comic book character * ''Challengers'' (manga), manga by Hinako Takanaga Film and TV * ''The Challengers'' (TV series), a 1979 ...
, Wye Northdown, Wye
Saxon The Saxons ( la, Saxones, german: Sachsen, ang, Seaxan, osx, Sahson, nds, Sassen, nl, Saksen) were a group of Germanic * * * * peoples whose name was given in the early Middle Ages to a large country (Old Saxony, la, Saxonia) near the Nor ...
and Wye
Yeoman Yeoman is a noun originally referring either to one who owns and cultivates land or to the middle ranks of servants in an English royal or noble household. The term was first documented in mid-14th-century England. The 14th century also witn ...
. More recently, Wye College and its successor institution Wye Hops Ltd., have focused on breeding the first
dwarf Dwarf or dwarves may refer to: Common uses *Dwarf (folklore), a being from Germanic mythology and folklore * Dwarf, a person or animal with dwarfism Arts, entertainment, and media Fictional entities * Dwarf (''Dungeons & Dragons''), a humanoid ...
hop varieties, which are easier to pick by machine and far more economical to grow. Wye College have also been responsible for breeding hop varieties that will grow with only 12 hours of daily light for the South African hop farmers. Wye College was closed in 2009 but the legacy of their hop breeding programs, particularly that of the dwarf varieties, is continuing as already the US private and public breeding programs are using their stock material. Particular hop varieties are associated with beer regions and styles, for example
pale lager Pale lager is a very pale-to-golden-colored lager beer with a well- attenuated body and a varying degree of noble hop bitterness. The brewing process for this beer developed in the mid-19th century, when Gabriel Sedlmayr took pale ale brewing ...
s are usually brewed with European (often German, Polish or Czech) noble hop varieties such as
Saaz Saaz may refer to: *Saaz, the former German name of Žatec, a town in the Czech Republic **Saaz hops, a hop variety used in production of pilsener style beer **DSV Saaz, a former football club in Žatec * ''Saaz'' (film), a 1998 Indian film * Saaz ...
, Hallertau and Strissel Spalt. British ales use hop varieties such as Fuggles, Goldings and W.G.V. North American beers often use
Cascade hops Cascade is one of the many cultivars of hops. Cascade hops are one of the most widely used hops by craft breweries in the United States. Cascade was the most widely planted hop by growers in the US for many years, before being surpassed by Citra ...
, Columbus hops, Centennial hops, Willamette,
Amarillo hops Amarillo is a popular brand name of the VGXP01 hops owned by Virgil Gamache Farms Inc. The VGXP01 c.v., was discovered by Virgil Gamache Farms Inc. in one of their hop yards in Washington (state), Washington state and propagated and introduced by t ...
and about forty more varieties as the US have lately been the more significant breeders of new hop varieties, including dwarf hop varieties. Hops from New Zealand, such as Pacific Gem, Motueka and Nelson Sauvin, are used in a "Pacific Pale Ale" style of beer with increasing production in 2014.


Noble hops

The term "noble hops" is a marketing term that traditionally refers to varieties of hops low in bitterness and high in
aroma An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sense ...
. They are the European
cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
s or races Hallertau, Tettnanger, Spalt, and
Saaz Saaz may refer to: *Saaz, the former German name of Žatec, a town in the Czech Republic **Saaz hops, a hop variety used in production of pilsener style beer **DSV Saaz, a former football club in Žatec * ''Saaz'' (film), a 1998 Indian film * Saaz ...
. Some proponents assert that the English varieties Fuggle, East Kent Goldings and Goldings might qualify as "noble hops" due to the similar composition, but such terms aren't applied to English varieties. Their low relative bitterness, but strong aroma, are often distinguishing characteristics of European-style
lager Lager () is beer which has been brewed and conditioned at low temperature. Lagers can be pale, amber, or dark. Pale lager is the most widely consumed and commercially available style of beer. The term "lager" comes from the German for "storage" ...
s, such as
Pilsener Pilsner (also pilsener or simply pils) is a type of pale lager. It takes its name from the Bohemian city of Plzeň (german: Pilsen), where the world's first pale lager (now known as Pilsner Urquell) was produced in 1842 by Pilsner Urquell Brewe ...
,
Dunkel Dunkel, or Dunkles, is a word used for several types of dark German lager. ''Dunkel'' is the German word meaning ''dark'', and dunkel beers typically range in color from amber to dark reddish brown. They are characterized by their smooth malty f ...
, and Oktoberfest/Märzen. In beer, they are considered aroma hops (as opposed to bittering hops); see
Pilsner Urquell Pilsner Urquell (; cs, Plzeňský prazdroj ) is a lager beer brewed by the Pilsner Urquell Brewery in Plzeň (German name: Pilsen), Czech Republic. Pilsner Urquell was the world's first pale lager, and its popularity meant it was much copied, ...
as a classic example of the Bohemian Pilsener style, which showcases noble hops. As with grapes, the location where hops are grown affects the hops' characteristics. Much as Dortmunder beer may within the EU be labelled "Dortmunder" only if it has been brewed in
Dortmund Dortmund (; Westphalian nds, Düörpm ; la, Tremonia) is the third-largest city in North Rhine-Westphalia after Cologne and Düsseldorf, and the eighth-largest city of Germany, with a population of 588,250 inhabitants as of 2021. It is the la ...
, noble hops may officially be considered "noble" only if they were grown in the areas for which the hop varieties ( races) were named. * Hallertau or Hallertauer – The original German lager hop; named after
Hallertau The Hallertau or Holledau is an area in Bavaria, Germany. With an area of 178 km², it is listed as the largest continuous hop-planting area in the world.Bentley, James; Catling, Christopher; & Locke, Tim (1994). ''Munich and Bavaria''. Chicago: ...
or Holledau region in central Bavaria. Due to susceptibility to crop disease, it was largely replaced by
Hersbruck Hersbruck () is a small town in Middle Franconia, Bavaria, Germany, belonging to the district Nürnberger Land. It is best known for the late-gothic artwork of the Hersbruck altar, the "Hirtenmuseum" and the landscape of Hersbruck Switzerland. Hi ...
er in the 1970s and 1980s. (Alpha acid 3.5–5.5% / beta acid 3–4%) * Spalt – Traditional German noble hop from the
Spalt Spalt (Northern Bavarian: ''Schbåld'') is a town in the Roth (district), district of Roth, in Bavaria, Germany. It is situated 19 km southwest of Schwabach. Spalt is famous for growing hops for brewing beer. Geography Spalt is situated betw ...
er region south of Nuremberg. With a delicate, spicy aroma. (Alpha acid 4–5% / beta acid 4–5%) * Tettnang – Comes from
Tettnang Tettnang is a town in the Bodensee district in southern Baden-Württemberg in a region of Germany known as Swabia. It lies 7 kilometres from Lake Constance. The region produces significant quantities of Tettnang hop, an ingredient of beer, an ...
, a small town in southern
Baden-Württemberg Baden-Württemberg (; ), commonly shortened to BW or BaWü, is a German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million inhabitants across a ...
in Germany. The region produces significant quantities of hops, and ships them to
breweries A brewery or brewing company is a business that makes and sells beer. The place at which beer is commercially made is either called a brewery or a beerhouse, where distinct sets of brewing equipment are called plant. The commercial brewing of bee ...
throughout the world. Noble German dual-use hop used in European pale lagers, sometimes with Hallertau. Soft bitterness. (Alpha acid 3.5–5.5% / beta acid 3.5–5.5%) * Žatec (Saaz) – Noble hop, named after
Žatec Žatec (; german: Saaz) is a town in Louny District in the Ústí nad Labem Region of the Czech Republic. It has about 19,000 inhabitants. It lies on the Ohře river. The town centre is well preserved and is protected by law as an urban monument ...
town, used extensively in Bohemia to flavour pale Czech lagers such as
Pilsner Urquell Pilsner Urquell (; cs, Plzeňský prazdroj ) is a lager beer brewed by the Pilsner Urquell Brewery in Plzeň (German name: Pilsen), Czech Republic. Pilsner Urquell was the world's first pale lager, and its popularity meant it was much copied, ...
. Soft aroma and bitterness. (Alpha acid 3–4.5% /Beta acid 3–4.5%) Noble hops are characterized through analysis as having an aroma quality resulting from numerous factors in the essential oil, such as an alpha:beta ratio of 1:1, low alpha-acid levels (2–5%) with a low cohumulone content, low myrcene in the hop oil, high humulene in the oil, a ratio of humulene:caryophyllene above three, and poor storability resulting in them being more prone to oxidation. In reality, this means they have a relatively consistent bittering potential as they age, due to beta-acid oxidation, and a flavor that improves as they age during periods of poor storage.


Other uses

In addition to beer, hops are used in
herbal tea Herbal teas, also known as herbal infusions and less commonly called tisanes (UK and US , US also ), are beverages made from the infusion or decoction of herbs, spices, or other plant material in hot water. Oftentimes herb tea, or the plain term ...
s and in soft drinks. These soft drinks include
Julmust ''Julmust'' ( sv, jul "yule" and ' English: 'must' "not-yet-fermented juice of fruit or berries", though there is no such juice in ''julmust'') is a soft drink that is mainly consumed in Sweden around Christmas. During Easter, the name is ' (from ...
(a carbonated beverage similar to soda that is popular in Sweden during December),
Malta Malta ( , , ), officially the Republic of Malta ( mt, Repubblika ta' Malta ), is an island country in the Mediterranean Sea. It consists of an archipelago, between Italy and Libya, and is often considered a part of Southern Europe. It lies ...
(a
Latin American Latin Americans ( es, Latinoamericanos; pt, Latino-americanos; ) are the citizens of Latin American countries (or people with cultural, ancestral or national origins in Latin America). Latin American countries and their diasporas are multi-eth ...
soft drink) and
kvass Kvass is a fermented cereal-based Alcohol by volume, low alcoholic beverage with a slightly cloudy appearance, light-brown colour and sweet-sour taste. It may be flavoured with berries, fruits, herbs or honey. Kvass stems from the northeastern ...
. Hops can be eaten; the young shoots of the bine are edible and can be cooked like
asparagus Asparagus, or garden asparagus, folk name sparrow grass, scientific name ''Asparagus officinalis'', is a perennial flowering plant species in the genus ''Asparagus''. Its young shoots are used as a spring vegetable. It was once classified in ...
. Hops may be used in
herbal medicine Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern remed ...
in a way similar to valerian, as a treatment for anxiety, restlessness, and insomnia. A pillow filled with hops is a popular folk remedy for sleeplessness, and animal research has shown a sedative effect. The relaxing effect of hops may be due, in part, to the specific degradation product from
alpha acid Alpha acids (α 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. Alpha acids may be isomerized ...
s, 2-methyl-3-buten-2-ol, as demonstrated from nighttime consumption of non-alcoholic beer. 2-methyl-3-buten-2-ol is structurally similar to
tert-amyl alcohol ''tert''-Amyl alcohol (TAA) or 2-methylbutan-2-ol (2M2B), is a branched pentanol. Historically TAA has been used an anesthetic and more recently used as a recreational drug. TAA is mostly a positive allosteric modulator for GABAA receptors in t ...
which was historically used as an anesthetic. Hops tend to be unstable when exposed to light or air and lose their potency after a few months' storage. Hops are of interest for
hormone replacement therapy Hormone replacement therapy (HRT), also known as menopausal hormone therapy or postmenopausal hormone therapy, is a form of hormone therapy used to treat symptoms associated with female menopause. These symptoms can include hot flashes, vaginal ...
and are under basic research for potential relief of menstruation-related problems.


Toxicity

Dermatitis Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can v ...
sometimes results from harvesting hops. Although few cases require medical treatment, an estimated 3% of the workers suffer some type of
skin lesions A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this sy ...
on the face, hands, and legs. Hops are toxic to
dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
s.


Fiction

Hops and hops picking form the milieu and atmosphere in the British detective novel, ''
Death in the Hopfields ''Death in the Hopfields'' is a 1937 detective novel by John Rhode, the pen name of the British writer Cecil Street. It is the twenty fifth in his long-running series of novels featuring Lancelot Priestley, a Golden Age armchair detective. It was ...
'' (1937) by
John Rhode Cecil John Charles Street (3 May 1884 – 8 December 1964), who was known to his colleagues, family and friends as John Street, began his military career as an artillery officer in the British Army. During the course of World War I, he became a ...
. The novel was subsequently issued in the United States under the title ''The Harvest Murder''.


See also

*
Gruit Gruit (alternately grut or gruyt) is a herb mixture used for bittering and flavouring beer, popular before the extensive use of hops. The terms gruit and grut ale may also refer to the beverage produced using gruit. Historically, gruit is the te ...
, an old-fashioned herb mixture used for bittering and flavouring beer, popular before the extensive use of hops * ''
Humulus lupulus ''Humulus lupulus'', the common hop or hops, is a species of flowering plant in the hemp family Cannabinaceae, native to Europe, western Asia and North America. It is a perennial, herbaceous climbing plant which sends up new shoots in early spr ...
'', the hop plant *
Mugwort Mugwort is a common name for several species of aromatic flowering plants in the genus ''Artemisia.'' In Europe, mugwort most often refers to the species '' Artemisia vulgaris'', or common mugwort. In East Asia the species '' Artemisia argyi'' i ...
, an herb historically used as a bitter in beer production *
Oast house An oast, oast house or hop kiln is a building designed for kilning (drying) hops as part of the brewing process. They can be found in most hop-growing (and former hop-growing) areas and are often good examples of vernacular architecture. Many re ...
, a building designed for drying hops * ''
Rhamnus prinoides ''Rhamnus prinoides'', the shiny-leaf buckthorn, is an African shrub or small tree in the family Rhamnaceae. Commonly referred to as "gesho" it was first scientifically described by French botanist Charles Louis L'Héritier de Brutelle in 1789. ...
'', a plant whose leaves are used in the Ethiopian variety of
mead Mead () is an alcoholic beverage made by fermenting honey mixed with water, and sometimes with added ingredients such as fruits, spices, grains, or hops. The alcoholic content ranges from about 3.5% ABV to more than 20%. The defining character ...
called
tej Tej (from pronounced ; ; ) is a honey wine, like mead, that is brewed and consumed in Ethiopia and Eritrea. It has an alcohol content generally ranging from 7 to 11%. It is often home processed and consists of three main ingredients; honey, wa ...


References


External links

* {{Cite NSRW, wstitle=Hop, short=x Brewing ingredients Crops originating from Europe Medicinal plants Medieval agriculture +