Editing Hops

{{Short description|Flower used to flavour beer and other beverages}}
{{Other uses|Hop (disambiguation){{!}}Hop}}
{{Use dmy dates|date=September 2021}}
[[File:Humulus Lupulus Hopfendolde-mit-hopfengarten.jpg|thumb|Hop flower in a hop yard in the [[Hallertau]], Germany]]
[[File:Cross-section of hop cone.svg|thumb|Cross-section drawing of a hop]]
[[File:Hops on the Yakima Reservation.jpg|alt=Full grown hops {{not a typo|bines}}.|thumb|upright=1.3|Fully grown [[Vine#Twining vines|hops bines]] ready for harvest on the [[Yakama Indian Reservation]]]]<!--Note to editors: 'bines' here is an actual word, not a typo-->
[[File:Decorative Hops.jpg|thumb|Humulus on a house]]

'''Hops''' are the [[flower]]s (also called seed cones or [[strobile]]s) of the hop plant ''[[Humulus lupulus]]'',<ref>{{Cite web |date=13 May 2008 |title=University of Minnesota Libraries: The Transfer of Knowledge. Hops-''Humulus lupulus'' |url=http://www.lib.umn.edu/botanical/plant.php |access-date=20 May 2012 |publisher=Lib.umn.edu |archive-date=5 March 2012 |archive-url=https://web.archive.org/web/20120305173530/http://www.lib.umn.edu/botanical/plant.php |url-status=dead }}</ref> a member of the [[Cannabaceae]] family of flowering plants.<ref>{{Cite encyclopedia |title=Cannabaceae {{!}} Description, Genera, & Species |encyclopedia=Encyclopedia Britannica |url=https://www.britannica.com/plant/Cannabaceae |access-date=16 September 2020 |language=en}}</ref> 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.<ref name="schon">{{Cite journal |last=Schönberger C, Kostelecky T |date=16 May 2012 |title=125th Anniversary Review: The Role of Hops in Brewing |journal=Journal of the Institute of Brewing |volume=117 |issue=3 |pages=259–267 |doi=10.1002/j.2050-0416.2011.tb00471.x |doi-access=free}}</ref> 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.<ref>{{Cite book |url=https://www.eolss.net/ebooklib/bookinfo/soils-plant-growth-crop-production.aspx |title=Soils, Plant Growth and Crop Production Volume II |date=2010 |publisher=[[EOLSS]] Publishers |isbn=978-1-84826-368-0 |editor-last=Willy H. Verheye |page=194 |chapter=Hops and Hop Growing}}</ref> 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.<ref>{{Cite book |last=Hornsey |first=Ian S. |url=https://books.google.com/books?id=QqnvNsgas20C&pg=PA305 |title=A History of Beer and Brewing |publisher=Royal Society of Chemistry |year=2003 |isbn=9780854046300 |page=305}}</ref> Before this period, brewers used a "[[gruit]]", composed of a wide variety of bitter herbs and flowers, including [[dandelion]], [[burdock root]], [[Calendula|marigold]], [[Common horehound|horehound]] (the old German name for horehound, {{lang|de|Berghopfen}}, means "mountain hops"), [[ground ivy]], and [[Calluna|heather]].<ref>{{Cite web |title=Understanding Beer – A Broad Overview of Brewing, Tasting and Analyzing Beer – October 12th, 2006, Beer & Brewing, The Brewing Process |url=http://jongriffin.com/articles/understanding-beer/ |url-status=dead |archive-url=https://web.archive.org/web/20120315195032/http://jongriffin.com/articles/understanding-beer/ |archive-date=15 March 2012 |access-date=20 May 2012 |website=www.jongriffin.com |publisher=Jongriffin.com}}</ref> Early documents include mention of a hop garden in the will of [[Charlemagne]]'s father, [[Pepin the Short]].<ref>{{Cite book |last=Michael Jackson |url=https://archive.org/details/newworldguidetob00mich/page/18 |title=The New World World Guide to Beer |publisher=Running Press |year=1988 |isbn=978-0-89471-884-7 |page=[https://archive.org/details/newworldguidetob00mich/page/18 18] |author-link=Michael Jackson (writer) |url-access=registration}}</ref>

Hops are also used in brewing for their [[Antibiotics|antibacterial]] effect over less desirable [[microorganisms]] and for purported benefits including balancing the sweetness of the [[malt]] with [[Bitterness (taste)|bitterness]] and a variety of flavours and aromas.<ref name=schon/> 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.<ref>{{Cite book |last1=F. G. Priest |url=https://books.google.com/books?id=jafz6LhdUbEC&pg=PA5 |title=Brewing microbiology |last2=Iain Campbell |publisher=Springer |year=2003 |isbn=978-0-306-47288-6 |page=5}}</ref>

==History==
The first documented hop cultivation was in 736, in the [[Hallertau]] region of present-day Germany.<ref>{{Cite book |last=Ian Hornsey |url=https://books.google.com/books?id=omwoDwAAQBAJ&pg=PA58 |title=Brewing |date=31 October 2007 |isbn=9781847550286 |page=58| publisher=Royal Society of Chemistry }}</ref> In 768, hop gardens were left to the Cloister of Saint-Denis in a will of [[Pepin the Short]], the father of [[Charlemagne]].<ref>{{Cite book |last=Unger |first=Richard W. |title=Beer in the Middle Ages and the Renaissance |date=2007 |publisher=University of Pennsylvania Press |isbn=978-0-8122-1999-9 |edition= |location=Philadelphia, Pennsylvania |pages=53–54}}</ref> The first mention of hops being used in German brewing was in 1079.<ref>{{Cite book |last=H.S. Corran |url=http://www.abebooks.com/servlet/BookDetailsPL?bi=17784589708&searchurl=isbn%3D0715367358%26tn%3DA%2520History%2520of%2520Brewing%26an%3Dcorran |title=History of Brewing |date=23 January 1975 |publisher=David and Charles PLC |isbn=978-0715367353 |page=303}}</ref>

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.<ref>{{Cite journal |last=Verberg |first=Susan |date=2020 |title=From Herbal to Hopped Beer: The Displacement of Regional Herb Beer Traditions by Commercial Export Brewing in Medieval Europe |url=https://www.researchgate.net/publication/346930430 |journal=Brewery History |volume=183 |pages=9–23 |via=ResearchGate}}</ref>

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".<ref>{{Cite book |last=Richard W. Unger |title=Beer in the Middle Ages and Renaissance |publisher=University of Pennsylvania Press |year=2004 |page=100}}</ref>

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.<ref>{{Cite journal |last=Mika Rissanen |title=The Reformation had some help from hops |url=https://www.academia.edu/28640210 |access-date=21 September 2016 |website=www.academia.edu}}</ref>

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 people|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.<ref>{{Cite book |last=Pocock |first=D. C. D. |title=England's diminished Hop-acreage |publisher=Geographical Association |year=1959 |pages=14–22}}</ref>

According to [[Thomas Tusser]]'s 1557 ''Five Hundred Points of Good Husbandry'':

<blockquote><poem>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.<ref>{{Cite magazine |last=Knight |first=Charles |author-link=Charles Knight (publisher) |year=1832 |url=https://archive.org/stream/ThePennyMagazineOfTheSocietyForTheDiffusionOfUsefulKnowledge/ThePennyMagazineOfTheSocietyForTheDiffusionOfUsefulKnowledge1832#page/n15/mode/2up |title=Antiquity of Beer |work=[[Penny Magazine|The Penny Magazine]] |page=3}}</ref></poem></blockquote>

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 VI and I|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".<ref>{{Cite book |last=Adam Anderson |url=https://archive.org/details/historicalchrono01ande |title=An Historical and Chronological Deduction of the Origin of Commerce |year=1764 |volume=1 |page=[https://archive.org/details/historicalchrono01ande/page/461 461] |author-link=Adam Anderson (economist)}}</ref>

Hop cultivation was begun in the present-day United States in 1629 by English and Dutch farmers.<ref>{{Cite book |last=Charles W. Bamforth |title=Beer: tap into the art and science of brewing |publisher=Plenum Press |year=1998 |isbn=978-0-306-45797-5 |page=245}}</ref> Before [[prohibition in the United States|prohibition]], cultivation was mainly centred around New York, California, Oregon, and [[Washington (state)|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.<ref>{{Cite web |last=Knight |first=Paul D. |title=HOPS IN BEER |url=http://www.usahops.org/index.cfm?fuseaction=hop_info&pageID=16 |url-status=dead |archive-url=https://web.archive.org/web/20150610130142/http://www.usahops.org/index.cfm?fuseaction=hop_info&pageID=16 |archive-date=10 June 2015 |access-date=11 June 2015 |website=USA Hops |publisher=Hop Growers of America}}</ref>

==World production==
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.<ref name="peicanada.com">{{Cite web |title=Hops industry has great potential for Atlantic Canada |url=https://www.peicanada.com/island_farmer/news/hops-industry-has-great-potential-for-atlantic-canada/article_647cda78-280a-5600-8676-20673eb7ba1f.html |website=peicanada.com|date=12 December 2012 }}</ref> Not all potato-growing areas can produce good hops naturally, however: for example, soils in the [[The Maritimes|Maritime Provinces]] of Canada lack the [[boron]] that hops prefer.<ref name="peicanada.com" /> Historically, hops were not grown in Ireland, but were imported from England. In 1752 more than 500 [[ton]]s of English hops were imported through Dublin alone.<ref>"The London magazine, 1752", page 332</ref>

Important production centres today are the [[Hallertau]] in Germany,<ref>[http://www.hmelj-giz.si/ihgc/doc/5-EC%20table%20Nov06.pdf Summary of Reports: Nürnberg, Germany, 14 November 2006], International Hop Growers' Convention: Economic Committee</ref> the [[Žatec]] ([[Saaz hops|Saaz]]) in the [[Czech Republic]], the [[Yakima River Valley|Yakima]] ([[Washington (state)|Washington]]) and [[Willamette Valley|Willamette]] (Oregon) valleys, and western Canyon County, Idaho (including the communities of [[Parma, Idaho|Parma]], [[Wilder, Idaho|Wilder]], [[Greenleaf, Idaho|Greenleaf]], and [[Notus, Idaho|Notus]]).<ref>{{Cite web |title=NCGR-Corvallis Humulus Genetic Resources |url=http://www.ars-grin.gov/cor/humulus/huminfo.html#use |access-date=20 May 2012 |website=www.ars-grin.gov |publisher=Ars-grin.gov}}</ref> The principal production centres in the UK are in [[Kent]] (which produces Kent Goldings hops), [[Herefordshire]], and [[Worcestershire]].<ref>Norman Moss, [http://www.hops.co.uk/sectionone/Worcester.htm A Fancy to Worcesters] {{webarchive|url=https://web.archive.org/web/20070929072147/http://www.hops.co.uk/sectionone/Worcester.htm |date=29 September 2007 }}, [http://www.ars-grin.gov Agricultural research Service], US Department of Agriculture</ref><ref>{{Cite web |title=Herefordshire Through Time – Welcome |url=http://www.smr.herefordshire.gov.uk/agriculture%20_industry/hops_history.htm |access-date=24 May 2012 |website=www.smr.herefordshire.gov.uk |publisher=Smr.herefordshire.gov.uk |archive-date=27 December 2008 |archive-url=https://web.archive.org/web/20081227010957/http://www.smr.herefordshire.gov.uk/agriculture%20_industry/hops_history.htm |url-status=dead }}</ref> Essentially all of the harvested hops are used in beer making.{{Cn|date=January 2021}}

[[File:Yakima-Valley-Hop-Yard.jpg|thumb|right|Early season hop growth in a hop yard in the [[Yakima River Valley]] of [[Washington (state)|Washington]] with [[Mount Adams (Washington)|Mount Adams]] in the distance]]

{| class="wikitable sortable"
|-
! Hop producing country || 2020 hop output in [[tonne]]s (t)<ref>{{Cite web |date=February 2021 |title=International Hop Growers' Convention – Economic Commission Summary Reports |url=https://hopfen.de/wp-content/uploads/22.02.2021-Summary-Reports-IHGC-Meeting.pdf |access-date=5 June 2021 |archive-date=5 June 2021 |archive-url=https://web.archive.org/web/20210605195423/https://hopfen.de/wp-content/uploads/22.02.2021-Summary-Reports-IHGC-Meeting.pdf |url-status=dead }}</ref>
|-
| United States || style="text-align:right;"| 47,541
|-
| Germany || style="text-align:right;"| 46,878
|-
| China || style="text-align:right;" | 7,044
|-
| Czech Republic || style="text-align:right;" | 5,925
|-
| Poland || style="text-align:right;"| 3,417
|- 
| Slovenia  || style="text-align:right;" | 2,723
|-
| Australia || style="text-align:right;" | 1,714
|-
| New Zealand || style="text-align:right;" | 1,250
|-
| UK/England || style="text-align:right;" | 924
|-
| Spain || style="text-align:right;" | 908
|-
|-
| France || style="text-align:right;" | 767
|-
|}

===Cultivation and harvest===
[[File:Chmelnice.jpg|thumb|left|A superstructure of overhead wires supports strings that in turn support [[Bine (botany)|bine]]s.]]

Although hops are grown in most of the continental United States and Canada,<ref>{{Cite web |title=Humulus lupulus L. common hop |url=http://plants.usda.gov/core/profile?symbol=HULU |access-date=13 September 2013 |website=USDA Plants database}}</ref> 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.<ref>{{Cite journal |last=Keegstra |first=Kenneth |date=1 October 2010 |title=Plant Cell Walls |journal=Plant Physiology |language=en |volume=154 |issue=2 |pages=483–486 |doi=10.1104/pp.110.161240 |issn=1532-2548 |pmc=2949028 |pmid=20921169}}</ref>

The hop plant's [[Plant reproductive morphology|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.<ref>{{Cite book |last=C. C. Ainsworth |title=Sex Determination in Plants |date=15 June 1999 |publisher=Garland Science |isbn=9780203345993 |volume=38 |pages=167–223 |chapter=5 Sex Determination in Plants |series=Current Topics in Developmental Biology |doi=10.1016/s0070-2153(08)60247-1 |pmid=9399079 |chapter-url=https://books.google.com/books?id=MmO6rXOyvasC&pg=PA146}}</ref> Because pollinated seeds are undesirable for brewing beer, only female plants are grown in hop fields, thus preventing pollination. Female plants are propagated [[Vegetative reproduction|vegetatively]], and male plants are culled if plants are grown from seeds.<ref>{{Cite web |title=Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries. Economic Plants and their Diseases, Pests and Weeds. ''Humulus lupulus'' |url=http://www.agroatlas.ru/cultural/Humulus_lupulus_K_en.htm |url-status=dead |archive-url=https://web.archive.org/web/20120310182625/http://www.agroatlas.ru/cultural/Humulus_lupulus_K_en.htm |archive-date=10 March 2012 |access-date=20 May 2012 |website=www.agroatlas.ru |publisher=Agroatlas.ru}}</ref>

Hop plants are planted in rows about {{convert|2|to|2.5|m|ft|0}} apart. Each spring, the roots send forth new [[bine (botany)|bine]]s 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.<ref>{{Cite web |date=22 October 2013 |title=Innovative Hopping Equipment: New Belgium's Dry Hop Dosing Skid |url=https://www.craftbrewingbusiness.com/equipment-systems/innovative-hopping-equipment-new-belgiums-dry-hop-dosing-skid/ |access-date=4 May 2021 |website=Craft Brewing Business |language=en-US}}</ref>

Hops are harvested at the end of summer.<ref>{{Cite web |date=21 November 2014 |title=The Anatomy of a Hop |url=https://craftbeeracademy.com/hop-anatomy/ |access-date=5 June 2021 |website=Craft Beer Academy |language=en-US}}</ref> The {{not a typo|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]].<ref>{{Cite web |title=How Hops are Harvested and Used in Brewing • Bale Breaker Brewing Company |url=https://www.balebreaker.com/blog/how-hops-are-harvested-and-used-in-brewing |access-date=5 June 2021 |website=www.balebreaker.com |archive-date=26 September 2022 |archive-url=https://web.archive.org/web/20220926115220/https://www.balebreaker.com/blog/how-hops-are-harvested-and-used-in-brewing |url-status=dead }}</ref>

[[File:Hops Lupulin Macro.jpg|thumb|Macro shot of lupulin on a hop's cone]]

{{Anchor|lupulin}}Hop cones contain different oils, such as lupulin, a yellowish, waxy substance, an [[oleoresin]], that imparts flavour and aroma to beer.<ref>{{Cite web |last=Andrew |first=Sewalish |title=Hops: Anatomy and Chemistry 101 |url=http://bioweb.uwlax.edu/bio203/s2009/sewalish_andr/Humulus%20Lupulus%20-%20Common%20Hops/Hop%20Anatomy%20and%20Chemistry%20101.html |access-date=13 September 2013 |website=bioweb.uwlax.edu |archive-date=27 September 2013 |archive-url=https://web.archive.org/web/20130927135922/http://bioweb.uwlax.edu/bio203/s2009/sewalish_andr/Humulus%20Lupulus%20-%20Common%20Hops/Hop%20Anatomy%20and%20Chemistry%20101.html |url-status=dead }}</ref> 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 ===
[[File:Kratky, Frantisek - Sklizen chmele (ca 1898).jpg|thumb|Hops harvest in the [[Kingdom of Bohemia]] (1898)]]
[[File:NMA.0063746 Humleplockning mellan Vånga och Näsum.jpg|thumb|Hops harvest in [[Skåne]], Sweden, in 1937]]

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 [[hopper hut|hoppers' huts]], with even the smallest children helping in the fields.<ref>{{Cite web |title=Connie's Homepage – Hop Picking in Kent |url=http://www.btinternet.com/~hunny.pot/homepage/hopping.html |url-status=dead |archive-url=https://archive.today/20120721103026/http://www.btinternet.com/~hunny.pot/homepage/hopping.html |archive-date=21 July 2012 |access-date=20 May 2012 |website=www.btinternet.com |publisher=Btinternet.com}}</ref><ref>{{Cite web |title=George Orwell: Hop-picking |url=http://theorwellprize.co.uk/george-orwell/by-orwell/essays-and-other-works/hop-picking/ |access-date=20 May 2012 |website=www.theorwellprize.co.uk |date=20 October 2010 |publisher=Theorwellprize.co.uk |archive-date=26 March 2012 |archive-url=https://web.archive.org/web/20120326084442/http://theorwellprize.co.uk/george-orwell/by-orwell/essays-and-other-works/hop-picking/ |url-status=dead }}</ref> 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, Worcestershire|Malvern]] area of Worcestershire. Some photographs have been preserved.<ref>Smith, Keith. ''Around Malvern in old photographs.''. Alan Sutton Publishing, Gloucester. {{ISBN|0-86299-587-6}}.</ref>

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.<ref>Kentish Gazette, 23 October 1866</ref> 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.<ref>Sarah Rogers, ‘The Nurses of the 1897 Maidstone Typhoid Epidemic: Social Class and Training. How representative were they of mid-nineteenth century nursing reforms?’ (Unpublished Master of Letters dissertation, Dundee, March 2016),</ref><ref>{{Cite journal |last=Hales |first=I. |date=1984 |title='Maidstone Typhoid Epidemic' |journal=Bygone Kent. |volume=5 |issue=4 |pages=217–223}}</ref>

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.<ref>{{Cite web |title=The Furiners: A Forgotten Story |url=https://www.brewtek.ca/the-furiners-a-forgotten-story#hop-tokens |access-date=22 July 2019 |website=www.brewtek.ca |archive-date=4 May 2020 |archive-url=https://web.archive.org/web/20200504221219/https://www.brewtek.ca/the-furiners-a-forgotten-story#hop-tokens |url-status=dead }}</ref>

[[File:Indian_hop_pickers,_Puget_Sound_region,_Washington,_ca_1893_(LAROCHE_78).jpeg|thumb|Puget Sound region, Washington, c. 1893]]

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, California|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.<ref name="DauenhauerPD">{{Cite news |last=Gaye LeBaron |author-link=Gaye LeBaron |date=29 June 2008 |title=Hops, once king of county's crops, helped put region on map |work=Press Democrat |url=https://news.google.com/newspapers?nid=1673&dat=20080629&id=IIZPAAAAIBAJ&pg=1979,6896317 |access-date=4 September 2012}}</ref> Dauenhauer Manufacturing Company remains a current producer of hop harvesting machines.<ref>{{cite web |url=http://dmfg.com/about/ |title=About |website=dmfg.com |access-date=3 August 2021}}</ref>

==Chemical composition==
In addition to water, cellulose, and various proteins, the chemical composition of hops consists of compounds important for imparting character to beer.<ref name=schon/><ref name="Verzele 32–48">{{Cite journal |last=M. Verzele |date=2 January 1986 |title=100 Years of Hop Chemistry and Its Relevance to Brewing |journal=Journal of the Institute of Brewing |volume=92 |issue=1 |pages=32–48 |doi=10.1002/j.2050-0416.1986.tb04372.x |issn=2050-0416 |doi-access=free}}</ref>

=== Alpha acids ===
[[File:Reaction-degradation-humulone.png|thumb|upright=1.5|Isomerization scheme of humulone]]

Probably the most important chemical compound within hops are the alpha acids or [[humulone]]s. During wort boiling, the humulones are thermally isomerized into iso-alpha acids or [[Isohumulone|''isohumulones'']], which are responsible for the bitter taste of beer.<ref name="De Keukeleire 108–112">{{Cite journal |last=Denis De Keukeleire |year=2000 |title=Fundamentals of beer and hop chemistry |journal=Química Nova |volume=23 |issue=1 |pages=108–112 |doi=10.1590/S0100-40422000000100019 |issn=0100-4042 |doi-access=free}}</ref>

=== Beta acids ===
[[File:Lupulone.svg|thumb|upright|Structure of [[lupulone]] (beta acid)]]

Hops contain beta acids or [[lupulone]]s. These are desirable for their aroma contributions to beer.<ref>{{Cite book |last1=Ortega-Heras |first1=M. |title=Encyclopedia of Food Sciences and Nutrition |last2=González-Sanjosé |first2=M.L. |date=2003 |publisher=Academic Press |isbn=9780122270550 |editor-last=Benjamin |editor-first=Caballero |edition=Second |pages=429–434 |chapter=BEERS {{!}} Wort Production |doi=10.1016/B0-12-227055-X/00087-0}}</ref>

=== Essential oils ===
The main components of hops essential oils are [[terpene]] [[hydrocarbon]]s consisting of [[myrcene]], [[humulene]] and [[caryophyllene]].<ref name="Verzele 32–48" /> 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.<ref name="Verzele 32–48" /> 

=== Flavonoids ===
[[File:8-Prenylnaringenin.svg|thumb|upright|Chemical structure of 8-prenylnaringenin]]

[[Xanthohumol]] is the principal [[flavonoid]] in hops. The other well-studied [[prenylflavonoid]]s are [[8-Prenylnaringenin]] and [[isoxanthohumol]]. Xanthohumol is under [[basic research]] for its potential properties, while 8-prenylnaringenin is a potent [[phytoestrogen]].<ref>{{Cite journal |last1=Stevens |first1=Jan F |last2=Page |first2=Jonathan E |date=1 May 2004 |title=Xanthohumol and related prenylflavonoids from hops and beer: to your good health! |journal=Phytochemistry |volume=65 |issue=10 |pages=1317–1330 |doi=10.1016/j.phytochem.2004.04.025 |pmid=15231405|bibcode=2004PChem..65.1317S }}</ref><ref>{{Cite journal |last1=Milligan |first1=S |last2=Kalita |first2=J |last3=Pocock |first3=V |last4=Heyerick |first4=A |last5=Cooman |first5=L De |last6=Rong |first6=H |last7=Keukeleire |first7=D De |year=2002 |title=Oestrogenic activity of the hop phyto-oestrogen, 8-prenylnaringenin |url=https://www.researchgate.net/publication/11494867 |journal=Reproduction |volume=123 |issue=2 |pages=235–242 |doi=10.1530/rep.0.1230235 |pmid=11866690 |doi-access=free}}</ref>

==Brewing==
{{More citations needed section|date=January 2021}}
[[File:The Employment of Women in Britain, 1914-1918 Q28334.jpg|thumb|English brewers dry-hopping casks of beer (1918)]]
[[File:Hops are used for beer brewing.JPG|thumb|right|Hops sample at the Moscow Brewing Company]]

Hops are usually dried in an oast house before they are used in the brewing process.<ref>{{Cite book |last=James S. Hough |url=https://books.google.com/books?id=TQuwGXt2NYAC&pg=PA78 |title=The Biotechnology of Malting and Brewing |publisher=Cambridge University Press |year=1991 |isbn=978-0-521-39553-3}}</ref> Undried or "wet" hops are sometimes (since c. 1990) used.<ref>{{Cite news |last=Elizabeth Aguilera |date=10 September 2008 |title=Hop harvest yields hip beer for brewer |work=Denver Post |url=http://www.denverpost.com/business/ci_10422358}}</ref><ref>Kristin Underwood [http://www.treehugger.com/files/2009/08/its-harvest-time-at-the-sierra-nevada-brewery.php "It's Harvest Time at the Sierra Nevada Brewery"] {{Webarchive|url=https://web.archive.org/web/20110913060917/http://www.treehugger.com/files/2009/08/its-harvest-time-at-the-sierra-nevada-brewery.php |date=13 September 2011 }}. Treehugger. 6 August 2009. Retrieved 20 March 2011.</ref>

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.<ref name=schon/>

'''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]]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]]s are [[isomer]]ized during the boil, and the impact of a given amount of hops is specified in [[International Bitterness Units scale|International Bitterness Units]]. On the other hand, unboiled hops are only mildly [[bitter (taste)|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). {{anchor|DryHopping}}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.<ref name=schon/> 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.<ref name=schon/>

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.<ref>{{Cite book |last=John Palmer |url=http://www.howtobrew.com/ |title=How to Brew |publisher=Brewers Publications |year=2006 |isbn=978-0-937381-88-5 |location=Boulder, CO |pages=41–44}}</ref> Hop acids also contribute to and stabilize the foam qualities of beer.<ref name=schon/>

Flavours and aromas are described appreciatively using terms which include "grassy", "floral", "citrus", "spicy", "piney", "lemony", "grapefruit", and "earthy".<ref name=schon/><ref>{{Cite book |url=https://books.google.com/books?id=ZZPTBwAAQBAJ&pg=PA867 |title=Malting and Brewing Science: Volume II Hopped Wort and Beer |vauthors=Hough JS, Briggs DE, Stevens R, Young TW |date=6 December 2012 |publisher=Springer |isbn=978-1-4615-1799-3 |page=867}}</ref>
Many [[pale lager]]s have fairly low hop influence, while lagers marketed as [[Pilsener]] or brewed in the Czech Republic may have noticeable noble hop aroma. Certain [[ale]]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]] 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.<ref>{{Cite web |last=Jan |date=2022-12-23 |title=Hops |url=https://beerwiki.org/hops/ |access-date=2022-12-29 |website=Beerwiki |language=en-US |archive-date=29 December 2022 |archive-url=https://web.archive.org/web/20221229212152/https://beerwiki.org/hops/ |url-status=dead }}</ref>

==Varieties==
{{Main article|List of hop varieties}}
{{More citations needed section|date=July 2014}}

===Breeding programmes===
There are many different varieties of hops used in brewing today. Historically, hops varieties were identified by geography, i.e., from the towns of [[Hallertau]], [[Spalt]], and [[Tettnang]] in [[Germany]],<ref name="Craft Beer & Brewing 2023">{{cite web | title=The Oxford Companion to Beer Definition of German hops | website=Craft Beer & Brewing | date=April 6, 2023 | url=http://beerandbrewing.com/dictionary/e02KFPB7Ey/ | access-date=April 6, 2023}}</ref> or the region writ large like the [[Humulus lupulus var. neomexicanus|Neomexicanus hops]] of [[New Mexico]].<ref name="Stephens 2021">{{cite web | last=Stephens | first=Hollie | title=The Rise of Neomexicanus | website=Craft Beer & Brewing | date=October 18, 2021 | url=https://beerandbrewing.com/the-rise-of-neomexicanus/ | access-date=April 6, 2023}}</ref> Others were named for the farmer who is recognized as first cultivating them, including Goldings or Fuggles from England,<ref name="BeerAdvocate 2016">{{cite web | title=Finding Mr. Fuggle: The Largely Mysterious History of England's Two Greatest Hop Varieties | website=BeerAdvocate | date=April 11, 2016 | url=https://www.beeradvocate.com/articles/13523/finding-mr-fuggle-the-largely-mysterious-history-of-englands-two-greatest-hop-varieties/ | access-date=April 6, 2023}}</ref> or by their growing habit like the Oregon Cluster.<ref>{{Cite web |title=Brewery History: 121, pp. 94–112 |url=http://www.breweryhistory.com/journal/archive/121/bh-121-094.htm |access-date=2 June 2017 |website=www.breweryhistory.com}}</ref>{{citation needed|date=July 2014}}

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 [[List of hop varieties#Brewer's Gold|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.<ref name="IBD APac">{{Cite web |last1=Capper |first1=Allison |last2=Darby |first2=Peter |date=24 March 2014 |title=What makes British Hops Unique in the world of Hop Growing? |url=http://www.britishhops.org.uk/wp-content/uploads/2014/06/Asia-Pacific-Final-Paper.pdf |url-status=dead |archive-url=https://web.archive.org/web/20140725154905/http://www.britishhops.org.uk/wp-content/uploads/2014/06/Asia-Pacific-Final-Paper.pdf |archive-date=25 July 2014 |access-date=4 July 2014 |website=www.britishhops.org.uk}}</ref>

Wye College continued its breeding program and again received attention in the 1970s, when Dr. Ray A. Neve released Wye [[List of hop varieties#Target|Target]], Wye [[Challenger hop|Challenger]], Wye [[List of hop varieties#Northdown|Northdown]], Wye [[List of hop varieties#Saxon|Saxon]] and Wye [[List of hop varieties#Yeoman|Yeoman]]. More recently, Wye College and its successor institution Wye Hops Ltd., have focused on breeding the first [[dwarfing|dwarf]] hop varieties, which are easier to pick by machine and far more economical to grow.<ref name="Brit Hops History">{{Cite web |title=History of Hops |url=http://www.britishhops.org.uk/history-of-hops/ |access-date=19 July 2014 |website=British Hop Association |archive-date=30 June 2017 |archive-url=https://web.archive.org/web/20170630041620/http://www.britishhops.org.uk/history-of-hops/ |url-status=dead }}</ref> 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]]s are usually brewed with European (often German, Polish or Czech) noble hop varieties such as [[Saaz hops|Saaz]], Hallertau and Strissel Spalt. [[Beer in England|British ales]] use hop varieties such as Fuggles, Goldings and W.G.V. [[Beer in the United States|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.<ref>{{Cite web |title=On Trade Preview 2014 |url=http://www.ontrade.co.uk/Backissues/Totp2014/files/assets/common/downloads/The_OnTrade_Preview_2014.pdf |website=www.ontrade.co.uk}}</ref>{{citation needed|date=October 2014}}

===Noble hops===
[[File:Hopfengarten.jpg|thumb|right|Mature hops growing in a hop yard in Germany]]

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]].<ref name="walsh">{{Cite web |last=Andrew Walsh |date=30 November 2001 |title=An Investigation into the Purity of Noble Hop Lineage |url=https://www.morebeer.com/articles/Noble_Hops |access-date=10 March 2019 |website=www.morebeer.com |publisher=More Beer; In: Brewing Techniques – Vol. 6, No.2}}</ref> They are the European [[cultivar]]s or races Hallertau, Tettnanger, Spalt, and [[Saaz hops|Saaz]].<ref>{{Cite web |title=Hop growers union of the Czech Republic |url=http://www.czhops.cz/index.php/en |access-date=20 May 2012 |website=www.czhops.cz |publisher=Czhops.cz}}</ref> 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 [[lager]]s, such as [[Pilsener]], [[Dunkel]], and [[Märzen|Oktoberfest/Märzen]]. In beer, they are considered aroma hops (as opposed to bittering hops);<ref name=walsh/> 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)|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 ([[Race (biology)|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 [[Hersbruck]]er in the 1970s and 1980s. (Alpha acid 3.5–5.5% / beta acid 3–4%)
* '''Spalt''': Traditional German noble hop from the [[Spalt]]er 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-Württemberg]] in Germany. The region produces significant quantities of hops, and ships them to [[brewery|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%)
* '''Žatec (Saaz)''': Noble hop, named after [[Žatec]] 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.<ref name=walsh/> 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.<ref name=walsh/><ref>{{Cite web |date=28 April 2000 |title=Hop Chemistry: Homebrew Science |url=http://www.byo.com/stories/article/indices/18-brewing-science/853-hop-chemistry-homebrew-science |url-status=dead |archive-url=https://web.archive.org/web/20100202165456/https://byo.com/stories/article/indices/18-brewing-science/853-hop-chemistry-homebrew-science |archive-date=2 February 2010 |access-date=20 May 2012 |website=www.byo.com |publisher=Byo.com}}</ref>

==Other uses==
[[File:2-methyl-3-buten-2-ol.svg|thumbnail|upright|2-methyl-3-buten-2-ol]]

Hops are used in [[herbal tea]]s, as well as soft drinks including [[julmust]] (a&nbsp;carbonated beverage similar to soda that is popular in Sweden during December), [[Malta (soft drink)|Malta]] (a&nbsp;[[Latin American]] soft drink), [[kvass]]{{citation needed|date=April 2018}} and [[hop water]].<ref name="The New York Times 19 April 2024">{{cite news |last1=Keough |first1=Ben |title=Hop Water Isn't Trying to Be Beer. That's Why We Like It. |url=https://www.nytimes.com/wirecutter/reviews/best-hop-water/ |access-date=14 August 2024 |work=[[The New York Times]] |date=19 April 2024}}</ref> Additionally, both the young shoots and young flowers are edible and can be cooked like [[asparagus]].<ref>{{Cite web |title=9 Perennial Vegetables You Can Plant Once, Harvest Forever … And Never Worry About Again |url=http://www.storageprepper.com/9-perennial-vegetables-you-can-plant-once-harvest-forever-and-never-worry-about-again/ |access-date=3 June 2017 |website=8 March 2017 |publisher=torageprepper.com |archive-date=23 April 2021 |archive-url=https://web.archive.org/web/20210423154418/https://storageprepper.com/9-perennial-vegetables-you-can-plant-once-harvest-forever-and-never-worry-about-again/ |url-status=dead }}</ref><ref name="eating">{{Cite news |last=Alexi Duggins |date=18 May 2015 |title='It's like eating a hedgerow': why do hop shoots cost €1,000 a kilo? |work=The Guardian |url=https://www.theguardian.com/lifeandstyle/wordofmouth/2015/may/18/its-like-eating-a-hedgerow-why-do-hop-shoots-cost-1000-a-kilo |access-date=3 June 2017}}</ref><ref>{{Cite book |last=Francis-Baker |first=Tiffany |title=Concise Foraging Guide |date=2021 |publisher=[[Bloomsbury Publishing|Bloomsbury]] |isbn=978-1-4729-8474-6 |series=[[The Wildlife Trusts]] |location=London |pages=41}}</ref>

Hops may be used in [[Herbalism|herbal medicine]] in a way similar to [[Valerian (herb)|valerian]], as a treatment for anxiety, restlessness, and insomnia.<ref>[http://www.pfaf.org/user/Plant.aspx?LatinName=Humulus+lupulus Plants for a Future: ''Humulus lupulus''] Plants for a Future. Retrieved 4 September 2012.</ref> A pillow filled with hops is a popular folk remedy for sleeplessness, and animal research has shown a sedative effect.<ref name="pmid22849837">{{Cite journal |vauthors=Franco L, Sánchez C, Bravo R, Rodriguez A, Barriga C, Juánez JC |year=2012 |title=The sedative effects of hops (Humulus lupulus), a component of beer, on the activity/rest rhythm |journal=Acta Physiologica Hungarica |volume=99 |issue=2 |pages=133–9 |doi=10.1556/APhysiol.99.2012.2.6 |pmid=22849837}}</ref> The relaxing effect of hops may be due, in part, to the specific degradation product from [[alpha acid]]s, 2-methyl-3-buten-2-ol, as demonstrated from nighttime consumption of non-alcoholic beer.<ref name="pmid22849837" /><ref name="pmid22815680">{{Cite journal |vauthors=Franco L, Sánchez C, Bravo R, Rodríguez AB, Barriga C, Romero E, Cubero J |year=2012 |title=The sedative effect of non-alcoholic beer in healthy female nurses |journal=PLOS ONE |volume=7 |issue=7 |pages=e37290 |bibcode=2012PLoSO...737290F |doi=10.1371/journal.pone.0037290 |pmc=3399866 |pmid=22815680 |doi-access=free}}</ref> 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.<ref>{{Cite web |date=12 June 2020 |title=How Long Do Hops Last? Do Hops Expire? (With Fridge & Freezer Chart) – Learning to Homebrew |url=https://learningtohomebrew.com/how-long-do-hops-last-freezer-fridge-sealed/ |access-date=28 April 2021}}</ref>

Hops are of interest for [[hormone replacement therapy]] and are under basic research for potential relief of menstruation-related problems.<ref name="planta">{{Cite journal |vauthors=Keiler AM, Zierau O, Kretzschmar G |year=2013 |title=Hop extracts and hop substances in treatment of menopausal complaints |journal=Planta Med. |volume=79 |issue=7 |pages=576–9 |doi=10.1055/s-0032-1328330 |pmid=23512496 |doi-access=free}}</ref>

== Toxicity ==
[[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.<ref>{{Cite web |date=7 January 1998 |title=Purdue University: Center for New Crops and Plant Products. ''Humulus lupulus'' L |url=http://www.hort.purdue.edu/newcrop/duke_energy/Humulus_lupulus.html#Toxicity |access-date=20 May 2012 |website=www.hort.purdue.edu |publisher=Hort.purdue.edu}}</ref> Hops are toxic to [[Dog health#Dangerous foods|dog]]s.<ref>{{Cite web |title=Animal Poison Control Center. Hops |url=http://www.aspca.org/pet-care/poison-control/plants/hops.html |access-date=20 May 2012 |website=www.aspca.org |publisher=ASPCA}}</ref>

== See also ==
{{Portal|Beer}}
* [[Mugwort]], an herb historically used as a bitter in beer production
* ''[[Rhamnus prinoides]]'', a plant whose leaves are used in the Ethiopian variety of [[mead]] called [[tej]]

==References==
{{Reflist|30em}}

== Further reading ==
* {{Cite web |title=Oregon Brewers Played an Outsized Role in Popularizing IPA |url=https://www.npr.org/2024/06/01/nx-s1-4985917/oregon-brewers-played-an-outsized-role-in-popularizing-ipa |work=[[All Things Considered]] |date=1 June 2024 |publisher=[[NPR]] |access-date=1 June 2024}}

== External links ==
{{Commons category|Hops}}
* [https://daily.jstor.org/plant-of-the-month-hops/ "Plant of the Month: Hops"] at ''[[JSTOR Daily]]'', June 29, 2022
* {{Cite NSRW|wstitle=Hop|short=x}}

[[Category:Brewing ingredients]]
[[Category:Crops originating from Europe]]
[[Category:Medicinal plants]]
[[Category:Medieval agriculture]]
[[Category:Humulus|+]]