Flower used to flavour beer and other beverages
For other uses, see
Hop
.
Hops
are the
flowers
(also called seed cones or
strobiles
) of the hop plant
Humulus lupulus
,
[1]
a member of the
Cannabaceae
family of flowering plants.
[2]
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.
[3]
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.
[4]
The hop plant is a vigorous, climbing,
herbaceous
perennial
, 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
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
, 300 years later, is often cited as the earliest documented source.
[5]
Before this period, brewers used a "
gruit
", composed of a wide variety of bitter herbs and flowers, including
dandelion
,
burdock root
,
marigold
,
horehound
(the old German name for horehound,
Berghopfen
, means "mountain hops"),
ground ivy
, and
heather
.
[6]
Early documents include mention of a hop garden in the will of
Charlemagne
's father,
Pepin the Short
.
[7]
Hops are also used in brewing for their
antibacterial
effect over less desirable
microorganisms
and for purported benefits including balancing the sweetness of the
malt
with
bitterness
and a variety of flavours and aromas.
[3]
It is believed that traditional herb combinations for beers were abandoned after it was noticed that beers made with hops were less prone to spoilage.
[8]
History
[
edit
]
The first documented hop cultivation was in 736, in the
Hallertau
region of present-day Germany,
[9]
although the first mention of the use of hops in brewing in that country was 1079.
[10]
However, in a will of
Pepin the Short
, the father of
Charlemagne
, hop gardens were left to the Cloister of Saint-Denis in 768.
[11]
Not until the 13th century did hops begin to start threatening the use of
gruit
for flavouring. Gruit was used when the nobility levied taxes on hops. Whichever was taxed made the brewer then quickly switch to the other.
[12]
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".
[13]
In 1471,
Norwich
, England, banned use of the plant in the brewing of
ale
("beer" was the name for fermented malt liquors bittered with hops; only in recent times are the words often used as synonyms).
[
citation needed
]
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.
[14]
Hops used in England were imported from France, Holland and Germany and were subject to
import duty
; it was not until 1524 that hops were first grown in the southeast of England (
Kent
), when they were introduced as an agricultural crop by
Dutch
farmers. Consequently, many words used in the hop industry derive from the
Dutch language
. Hops were then grown as far north as
Aberdeen
, near breweries for convenience of infrastructure.
[15]
According to
Thomas Tusser
's 1557
Five Hundred Points of Good Husbandry
:
"The hop for his profit I thus do exalt,
It strengtheneth drink and it flavored malt;
And being well-brewed long kept it will last,
And drawing abide, if ye draw not too fast."
[16]
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
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".
[17]
Hop cultivation was begun in the present-day United States in 1629 by English and Dutch farmers.
[18]
Before
prohibition
, cultivation was mainly centred around New York, California, Oregon, and
Washington state
. Problems with
powdery mildew
and
downy mildew
devastated New York's production by the 1920s, and California only produces hops on a small scale.
[19]
World production
[
edit
]
Hops production is concentrated in moist temperate climates, with much of the world's production occurring near the
48th parallel north
. Hop plants prefer the same soils as potatoes and the leading potato-growing states in the United States are also major hops-producing areas;
[20]
however, not all potato-growing areas can produce good hops naturally: soils in the
Maritime Provinces
of Canada, for example, lack the
boron
that hops prefer.
[20]
Historically, hops were not grown in Ireland, but were imported from England. In 1752 more than 500
tons
of English hops were imported through Dublin alone.
[21]
Important production centres today are the
Hallertau
in Germany,
[22]
the
?atec
(
Saaz
) in the
Czech Republic
, the
Yakima
(
Washington
) and
Willamette
(Oregon) valleys, and western Canyon County, Idaho (including the communities of
Parma
,
Wilder
,
Greenleaf
, and
Notus
).
[23]
The principal production centres in the UK are in
Kent
(which produces Kent Goldings hops),
Herefordshire
, and
Worcestershire
.
[24]
[25]
Essentially all of the harvested hops are used in beer making.
[
citation needed
]
Hop producing country
|
2020 hop output in
tonnes
(t)
[26]
|
United States
|
47,541
|
Germany
|
46,878
|
China
|
7,044
|
Czech Republic
|
5,925
|
Poland
|
3,417
|
Slovenia
|
2,723
|
Australia
|
1,714
|
New Zealand
|
1,250
|
UK/England
|
924
|
Spain
|
908
|
France
|
767
|
Cultivation and harvest
[
edit
]
Although hops are grown in most of the continental United States and Canada,
[27]
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.
[28]
The hop plant's
reproduction
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.
[29]
Because pollinated seeds are undesirable for brewing beer, only female plants are grown in hop fields, thus preventing pollination. Female plants are propagated
vegetatively
, and male plants are culled if plants are grown from seeds.
[30]
Hop plants are planted in rows about 2 to 2.5 metres (7 to 8 ft) 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
in 1909.
[31]
Hops are harvested at the end of summer.
[32]
The bines are cut down, separated, and then dried in an
oast house
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
.
[33]
Hop cones contain different oils, such as lupulin, a yellowish, waxy substance, an
oleoresin
, that imparts flavour and aroma to beer.
[34]
Lupulin contains
lupulone
and
humulone
, 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
[
edit
]
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.
[35]
[36]
The final chapters of
W. Somerset Maugham
's
Of Human Bondage
and a large part of
George Orwell
's
A Clergyman's Daughter
contain a vivid description of London families participating in this annual hops harvest. In England, many of those picking hops in
Kent
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
area of Worcestershire. Some photographs have been preserved.
[37]
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
, 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.
[38]
The hop-pickers were given very basic accommodation, with very poor sanitation. This led to the spread of infectious diseases and led to contaminated water. The 1897
Maidstone typhoid epidemic
was partly as a result of hop-pickers camping near the Farleigh Springs which supplied Maidstone with water.
[39]
[40]
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.
[41]
In the United States,
Prohibition
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
, among others. Florian Dauenhauer, of
Santa Rosa
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.
[42]
Dauenhauer Manufacturing Company remains a current producer of hop harvesting machines.
[43]
Chemical composition
[
edit
]
In addition to water, cellulose, and various proteins, the chemical composition of hops consists of compounds important for imparting character to beer.
[3]
[44]
Alpha acids
[
edit
]
Probably the most important chemical compound within hops are the alpha acids or
humulones
. During wort boiling, the humulones are thermally isomerized into iso-alpha acids or
isohumulones
, which are responsible for the bitter taste of beer.
[45]
Beta acids
[
edit
]
Hops contain beta acids or
lupulones
. These are desirable for their aroma contributions to beer.
[46]
Essential oils
[
edit
]
The main components of hops essential oils are
terpene
hydrocarbons
consisting of
myrcene
,
humulene
and
caryophyllene
.
[44]
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.
[44]
Flavonoids
[
edit
]
Xanthohumol
is the principal
flavonoid
in hops. The other well-studied
prenylflavonoids
are
8-Prenylnaringenin
and
isoxanthohumol
. Xanthohumol is under
basic research
for its potential properties, while 8-prenylnaringenin is a potent
phytoestrogen
.
[47]
[48]
Brewing
[
edit
]
Hops are usually dried in an
oast house
before they are used in the brewing process.
[49]
Undried or "wet" hops are sometimes (since c. 1990) used.
[50]
[51]
The
wort
(sugar-rich liquid produced from
malt
) is boiled with hops before it is cooled down and
yeast
is added, to start
fermentation
.
The effect of hops on the finished beer varies by type and use, though there are two main hop types: bittering and aroma.
[3]
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
cultivars
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 acids
are
isomerized
during the boil, and the impact of a given amount of hops is specified in
International Bitterness Units
. On the other hand, unboiled hops are only mildly
bitter
.
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
is a major component in some hops.
[3]
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.
[3]
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.
[52]
Hop acids also contribute to and stabilize the foam qualities of beer.
[3]
Flavours and aromas are described appreciatively using terms which include "grassy", "floral", "citrus", "spicy", "piney", "lemony", "grapefruit", and "earthy".
[3]
[53]
Many
pale lagers
have fairly low hop influence, while lagers marketed as
Pilsener
or brewed in the Czech Republic may have noticeable noble hop aroma. Certain
ales
(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
allowing the reproduction of a recipe allowing for differences in hop availability.
Lately the dried pucks, extracts and pellets replace whole hops in brewing processes because of efficiency and cost.
[54]
Varieties
[
edit
]
Breeding programmes
[
edit
]
There are many different varieties of hops used in brewing today. Historically, hops varieties were identified by geography, ie. from the towns of
Hallertau
,
Spalt
, and
Tettnang
in
Germany
,
[55]
or the region writ large like the
Neomexicanus hops
of
New Mexico
.
[56]
Others were named for the farmer who is recognized as first cultivating them, including Goldings or Fuggles from England,
[57]
or by their growing habit like the Oregon Cluster.
[58]
[
citation needed
]
Around 1900, a number of institutions began to experiment with breeding specific hop varieties. The breeding program at
Wye College
in
Wye, Kent
, was started in 1904 and rose to prominence through the work of Prof.
E. S. Salmon
. 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.
[59]
Wye College continued its breeding program and again received attention in the 1970s, when Dr. Ray A. Neve released Wye
Target
, Wye
Challenger
, Wye
Northdown
, Wye
Saxon
and Wye
Yeoman
. More recently, Wye College and its successor institution Wye Hops Ltd., have focused on breeding the first
dwarf
hop varieties, which are easier to pick by machine and far more economical to grow.
[60]
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 lagers
are usually brewed with European (often German, Polish or Czech) noble hop varieties such as
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
, Columbus hops, Centennial hops, Willamette,
Amarillo hops
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.
[61]
[
citation needed
]
Noble hops
[
edit
]
The term "noble hops" is a marketing term that traditionally refers to certain varieties of hops that became known for being low in bitterness and high in
aroma
.
[62]
They are the European
cultivars
or races Hallertau, Tettnanger, Spalt, and
Saaz
.
[63]
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 are not applied to English varieties. Their low relative bitterness, but strong aroma, are often distinguishing characteristics of European-style
lagers
, such as
Pilsener
,
Dunkel
, and
Oktoberfest/Marzen
. In beer, they are considered aroma hops (as opposed to bittering hops);
[62]
see
Pilsner Urquell
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
, 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
or Holledau region in central Bavaria. Due to susceptibility to crop disease, it was largely replaced by
Hersbrucker
in the 1970s and 1980s. (Alpha acid 3.5?5.5% / beta acid 3?4%)
- Spalt
? Traditional German noble hop from the
Spalter
region south of Nuremberg. With a delicate, spicy aroma. (Alpha acid 4?5% / beta acid 4?5%)
- Tettnang
? Comes from
Tettnang
, a small town in southern
Baden-Wurttemberg
in Germany. The region produces significant quantities of hops, and ships them to
breweries
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%)
- ?atec (Saaz)
? Noble hop, named after
?atec
town, used extensively in Bohemia to flavour pale Czech lagers such as
Pilsner Urquell
. 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.
[62]
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.
[62]
[64]
Other uses
[
edit
]
In addition to beer, hops are used in
herbal teas
and in soft drinks. These soft drinks include
Julmust
(a carbonated beverage similar to soda that is popular in Sweden during December),
Malta
(a
Latin American
soft drink) and
kvass
.
[
citation needed
]
Hops can be eaten; the young shoots of the vine are edible and can be cooked like
asparagus
.
[65]
[66]
Hops may be used in
herbal medicine
in a way similar to
valerian
, as a treatment for anxiety, restlessness, and insomnia.
[67]
A pillow filled with hops is a popular folk remedy for sleeplessness, and animal research has shown a sedative effect.
[68]
The relaxing effect of hops may be due, in part, to the specific degradation product from
alpha acids
, 2-methyl-3-buten-2-ol, as demonstrated from nighttime consumption of non-alcoholic beer.
[68]
[69]
2-methyl-3-buten-2-ol is structurally similar to
tert-amyl alcohol
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.
[70]
Hops are of interest for
hormone replacement therapy
and are under basic research for potential relief of menstruation-related problems.
[71]
Toxicity
[
edit
]
Dermatitis
sometimes results from harvesting hops. Although few cases require medical treatment, an estimated 3% of the workers suffer some type of
skin lesions
on the face, hands, and legs.
[72]
Hops are toxic to
dogs
.
[73]
Fiction
[
edit
]
Hops and hops picking form the milieu and atmosphere in the British detective novel,
Death in the Hopfields
(1937) by
John Rhode
.
[74]
The novel was subsequently issued in the United States under the title
The Harvest Murder
.
[75]
See also
[
edit
]
- Gruit
, an old-fashioned herb mixture used for bittering and flavouring beer, popular before the extensive use of hops
- Humulus lupulus
, the hop plant
- Mugwort
, an herb historically used as a bitter in beer production
- Oast house
, a building designed for drying hops
- Rhamnus prinoides
, a plant whose leaves are used in the Ethiopian variety of
mead
called
tej
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[
edit
]
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- ^
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a
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f
g
h
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- ^
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