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Hops

From Wikipedia, the free encyclopedia
For other uses, seeHop.

Hop flower in a hop yard in theHallertau,Germany
Cross-section drawing of a hop
Full grown hops bines.
Fully grownhops binesready for harvest on theYakama Indian Reservation
Humulus on a house

Hopsare theflowers(also called seed cones orstrobiles) of the hop plantHumulus lupulus,[1]a member of theCannabaceaefamily of flowering plants.[2]They are used primarily as a bittering, flavouring, and stability agent inbeer,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 andherbal 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,herbaceousperennial,usually trained to grow up strings in a field called a hopfield, hop garden (in the South of England), or hop yard (in theWest Countryand 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, thoughHildegard 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, includingdandelion,burdock root,marigold,horehound(the old German name for horehound,Berghopfen,means "mountain hops" ),ground ivy,andheather.[6]Early documents include mention of a hop garden in the will ofCharlemagne's father,Pepin the Short.[7]

Hops are also used in brewing for theirantibacterialeffect over less desirablemicroorganismsand for purported benefits including balancing the sweetness of themaltwithbitternessand 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 theHallertauregion 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 ofPepin the Short,the father ofCharlemagne,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 ofgruitfor 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 ofale( "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 toimport 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 byDutchfarmers. Consequently, many words used in the hop industry derive from theDutch language.Hops were then grown as far north asAberdeen,near breweries for convenience of infrastructure.[15]

According toThomas Tusser's 1557Five 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, KingJames Iapproved 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]Beforeprohibition,cultivation was mainly centred around New York, California, Oregon, andWashington state.Problems withpowdery mildewanddowny mildewdevastated 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 the48th 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 theMaritime Provincesof Canada, for example, lack theboronthat hops prefer.[20]Historically, hops were not grown in Ireland, but were imported from England. In 1752 more than 500tonsof English hops were imported through Dublin alone.[21]

Important production centres today are theHallertauin Germany,[22]theŽatec(Saaz) in theCzech Republic,theYakima(Washington) andWillamette(Oregon) valleys, and western Canyon County, Idaho (including the communities ofParma,Wilder,Greenleaf,andNotus).[23]The principal production centres in the UK are inKent(which produces Kent Goldings hops),Herefordshire,andWorcestershire.[24][25]Essentially all of the harvested hops are used in beer making.[citation needed]

Early season hop growth in a hop yard in theYakima River ValleyofWashingtonwithMount Adamsin the distance
Hop producing country 2020 hop output intonnes(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]
A superstructure of overhead wires supports strings that in turn supportbines.

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'sreproductionmethod 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 propagatedvegetatively,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 newbinesthat 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 byEmil Clemens Horstin 1909.[31]

Hops are harvested at the end of summer.[32]The bines are cut down, separated, and then dried in anoast houseto 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 abaler.[33]

Hop cones contain different oils, such as lupulin, a yellowish, waxy substance, anoleoresin,that imparts flavour and aroma to beer.[34]Lupulin containslupuloneandhumulone,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]
Hops harvest in theKingdom of Bohemia(1898)
Hops harvest inSkåne,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 inhoppers' huts,with even the smallest children helping in the fields.[35][36]The final chapters ofW. Somerset Maugham'sOf Human Bondageand a large part ofGeorge Orwell'sA Clergyman's Daughtercontain a vivid description of London families participating in this annual hops harvest. In England, many of those picking hops inKentwere 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 theMalvernarea 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 1897Maidstone typhoid epidemicwas 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]

Puget Sound region, Washington, ca. 1893

In the United States,Prohibitionhad 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 throughoutSonoma County, California,among others. Florian Dauenhauer, ofSanta Rosain 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]
Isomerization scheme of humulone

Probably the most important chemical compound within hops are the alpha acids orhumulones.During wort boiling, the humulones are thermally isomerized into iso-alpha acids orisohumulones,which are responsible for the bitter taste of beer.[45]

Beta acids

[edit]
Structure oflupulone(beta acid)

Hops contain beta acids orlupulones.These are desirable for their aroma contributions to beer.[46]

Essential oils

[edit]

The main components of hops essential oils areterpenehydrocarbonsconsisting ofmyrcene,humuleneandcaryophyllene.[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]
Chemical structure of 8-prenylnaringenin

Xanthohumolis the principalflavonoidin hops. The other well-studiedprenylflavonoidsare8-Prenylnaringeninandisoxanthohumol.Xanthohumol is underbasic researchfor its potential properties, while 8-prenylnaringenin is a potentphytoestrogen.[47][48]

Brewing

[edit]
Hops sample at the Moscow Brewing Company

Hops are usually dried in anoast housebefore they are used in the brewing process.[49] Undried or "wet" hops are sometimes (since c. 1990) used.[50][51]

Thewort(sugar-rich liquid produced frommalt) is boiled with hops before it is cooled down andyeastis added, to startfermentation.

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 hopshave 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 Americancultivarstypically range from 8–19% AABW.

Aroma hopsusually 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 whichalpha acidsareisomerizedduring the boil, and the impact of a given amount of hops is specified inInternational Bitterness Units.On the other hand, unboiled hops are only mildlybitter.

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.Farneseneis 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]

Macro shot of lupulin on a hop's cone

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] Manypale lagershave fairly low hop influence, while lagers marketed asPilseneror brewed in the Czech Republic may have noticeable noble hop aroma. Certainales(particularly the highly hopped style known asIndia 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 viaBeerXMLallowing 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]
Main article:List of hop varieties

Breeding programmes

[edit]

There are many different varieties of hops used in brewing today. Historically, hops varieties were identified by geography, i.e., from the towns ofHallertau,Spalt,andTettnanginGermany,[55]or the region writ large like theNeomexicanus hopsofNew 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 atWye CollegeinWye, Kent,was started in 1904 and rose to prominence through the work of Prof.E. S. Salmon.Salmon releasedBrewer's Goldand 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 WyeTarget,WyeChallenger,WyeNorthdown,WyeSaxonand WyeYeoman.More recently, Wye College and its successor institution Wye Hops Ltd., have focused on breeding the firstdwarfhop 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 examplepale lagersare usually brewed with European (often German, Polish or Czech) noble hop varieties such asSaaz,Hallertau and Strissel Spalt.British alesuse hop varieties such as Fuggles, Goldings and W.G.V.North American beersoften useCascade hops,Columbus hops, Centennial hops, Willamette,Amarillo hopsand 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]
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 inaroma.[62]They are the Europeancultivarsor races Hallertau, Tettnanger, Spalt, andSaaz.[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-stylelagers,such asPilsener,Dunkel,andOktoberfest/Märzen.In beer, they are considered aroma hops (as opposed to bittering hops);[62]seePilsner Urquellas 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 asDortmunder beermay within the EU be labelled "Dortmunder" only if it has been brewed inDortmund,noble hops may officially be considered "noble" only if they were grown in the areas for which the hop varieties (races) were named.

  • HallertauorHallertauer– The original German lager hop; named afterHallertauor Holledau region in central Bavaria. Due to susceptibility to crop disease, it was largely replaced byHersbruckerin the 1970s and 1980s. (Alpha acid 3.5–5.5% / beta acid 3–4%)
  • Spalt– Traditional German noble hop from theSpalterregion south of Nuremberg. With a delicate, spicy aroma. (Alpha acid 4–5% / beta acid 4–5%)
  • Tettnang– Comes fromTettnang,a small town in southernBaden-Württembergin Germany. The region produces significant quantities of hops, and ships them tobreweriesthroughout 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 afterŽatectown, used extensively in Bohemia to flavour pale Czech lagers such asPilsner 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]
2-methyl-3-buten-2-ol

In addition to beer, hops are used inherbal teasand in soft drinks. These soft drinks includeJulmust(a carbonated beverage similar to soda that is popular in Sweden during December),Malta(aLatin Americansoft drink) andkvass.[citation needed]Hops can be eaten; the young shoots of the vine are edible and can be cooked likeasparagus.[65][66]

Hops may be used inherbal medicinein a way similar tovalerian,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 fromalpha 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 totert-amyl alcoholwhich 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 forhormone replacement therapyand are under basic research for potential relief of menstruation-related problems.[71]

Toxicity

[edit]

Dermatitissometimes results from harvesting hops. Although few cases require medical treatment, an estimated 3% of the workers suffer some type ofskin lesionson the face, hands, and legs.[72]Hops are toxic todogs.[73]

Fiction

[edit]

Hops and hops picking form the milieu and atmosphere in the British detective novel,Death in the Hopfields(1937) byJohn Rhode.[74]The novel was subsequently issued in the United States under the titleThe 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 ofmeadcalledtej

References

[edit]
  1. ^"University of Minnesota Libraries: The Transfer of Knowledge. Hops-Humulus lupulus".Lib.umn.edu. 13 May 2008. Archived fromthe originalon 5 March 2012.Retrieved20 May2012.
  2. ^"Cannabaceae | Description, Genera, & Species".Encyclopedia Britannica.Retrieved16 September2020.
  3. ^abcdefghSchönberger C, Kostelecky T (16 May 2012)."125th Anniversary Review: The Role of Hops in Brewing".Journal of the Institute of Brewing.117(3): 259–267.doi:10.1002/j.2050-0416.2011.tb00471.x.
  4. ^Willy H. Verheye, ed. (2010). "Hops and Hop Growing".Soils, Plant Growth and Crop Production Volume II.EOLSSPublishers. p. 194.ISBN978-1-84826-368-0.
  5. ^Hornsey, Ian S. (2003).A History of Beer and Brewing.Royal Society of Chemistry. p. 305.ISBN9780854046300.
  6. ^"Understanding Beer – A Broad Overview of Brewing, Tasting and Analyzing Beer – October 12th, 2006, Beer & Brewing, The Brewing Process".www.jongriffin.com.Jongriffin.com. Archived fromthe originalon 15 March 2012.Retrieved20 May2012.
  7. ^Michael Jackson(1988).The New World World Guide to Beer.Running Press. p.18.ISBN978-0-89471-884-7.
  8. ^F. G. Priest; Iain Campbell (2003).Brewing microbiology.Springer. p. 5.ISBN978-0-306-47288-6.
  9. ^Ian Hornsey (31 October 2007).Brewing.Royal Society of Chemistry. p. 58.ISBN9781847550286.
  10. ^H.S. Corran (23 January 1975).History of Brewing.David and Charles PLC. p. 303.ISBN978-0715367353.
  11. ^Unger, Richard W. (2007).Beer in the Middle Ages and the Renaissance.Philadelphia, Pennsylvania: University of Pennsylvania Press. pp. 53–54.ISBN978-0-8122-1999-9.
  12. ^Verberg, Susan (2020)."From Herbal to Hopped Beer: The Displacement of Regional Herb Beer Traditions by Commercial Export Brewing in Medieval Europe".Brewery History.183:9–23 – via ResearchGate.
  13. ^Richard W. Unger (2004).Beer in the Middle Ages and Renaissance.University of Pennsylvania Press. p. 100.
  14. ^Mika Rissanen."The Reformation had some help from hops".www.academia.edu.Retrieved21 September2016.
  15. ^Pocock, D. C. D. (1959).England's diminished Hop-acreage.Geographical Association. pp. 14–22.
  16. ^Knight, Charles(1832)."Antiquity of Beer".The Penny Magazine.p. 3.
  17. ^Adam Anderson(1764).An Historical and Chronological Deduction of the Origin of Commerce.Vol. 1. p.461.
  18. ^Charles W. Bamforth (1998).Beer: tap into the art and science of brewing.Plenum Press. p. 245.ISBN978-0-306-45797-5.
  19. ^Knight, Paul D."HOPS IN BEER".USA Hops.Hop Growers of America. Archived fromthe originalon 10 June 2015.Retrieved11 June2015.
  20. ^ab"Hops industry has great potential for Atlantic Canada".peicanada.com.12 December 2012.
  21. ^"The London magazine, 1752", page 332
  22. ^Summary of Reports: Nürnberg, Germany, 14 November 2006,International Hop Growers' Convention: Economic Committee
  23. ^"NCGR-Corvallis Humulus Genetic Resources".www.ars-grin.gov.Ars-grin.gov.Retrieved20 May2012.
  24. ^Norman Moss,A Fancy to WorcestersArchived29 September 2007 at theWayback Machine,Agricultural research Service,US Department of Agriculture
  25. ^"Herefordshire Through Time – Welcome".www.smr.herefordshire.gov.uk.Smr.herefordshire.gov.uk. Archived fromthe originalon 27 December 2008.Retrieved24 May2012.
  26. ^"International Hop Growers' Convention – Economic Commission Summary Reports"(PDF).February 2021.Retrieved5 June2021.
  27. ^"Humulus lupulus L. common hop".USDA Plants database.Retrieved13 September2013.
  28. ^Keegstra, Kenneth (1 October 2010)."Plant Cell Walls".Plant Physiology.154(2): 483–486.doi:10.1104/pp.110.161240.ISSN1532-2548.PMC2949028.PMID20921169.
  29. ^C. C. Ainsworth (15 June 1999)."5 Sex Determination in Plants".Sex Determination in Plants.Current Topics in Developmental Biology. Vol. 38. Garland Science. pp. 167–223.doi:10.1016/s0070-2153(08)60247-1.ISBN9780203345993.PMID9399079.
  30. ^"Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries. Economic Plants and their Diseases, Pests and Weeds.Humulus lupulus".www.agroatlas.ru.Agroatlas.ru. Archived fromthe originalon 10 March 2012.Retrieved20 May2012.
  31. ^"Innovative Hopping Equipment: New Belgium's Dry Hop Dosing Skid".Craft Brewing Business.22 October 2013.Retrieved4 May2021.
  32. ^"The Anatomy of a Hop".Craft Beer Academy.21 November 2014.Retrieved5 June2021.
  33. ^"How Hops are Harvested and Used in Brewing • Bale Breaker Brewing Company".www.balebreaker.com.Archived fromthe originalon 26 September 2022.Retrieved5 June2021.
  34. ^Andrew, Sewalish."Hops: Anatomy and Chemistry 101".bioweb.uwlax.edu.Retrieved13 September2013.
  35. ^"Connie's Homepage – Hop Picking in Kent".www.btinternet.com.Btinternet.com. Archived fromthe originalon 21 July 2012.Retrieved20 May2012.
  36. ^"George Orwell: Hop-picking".www.theorwellprize.co.uk.Theorwellprize.co.uk. 20 October 2010. Archived fromthe originalon 26 March 2012.Retrieved20 May2012.
  37. ^Smith, Keith.Around Malvern in old photographs..Alan Sutton Publishing, Gloucester.ISBN0-86299-587-6.
  38. ^Kentish Gazette, 23 October 1866
  39. ^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),
  40. ^Hales, I. (1984). "'Maidstone Typhoid Epidemic'".Bygone Kent.5(4): 217–223.
  41. ^"The Furiners: A Forgotten Story".www.brewtek.ca.Archived fromthe originalon 4 May 2020.Retrieved22 July2019.
  42. ^Gaye LeBaron(29 June 2008)."Hops, once king of county's crops, helped put region on map".Press Democrat.Retrieved4 September2012.
  43. ^"About".dmfg.com.Retrieved3 August2021.
  44. ^abcM. Verzele (2 January 1986)."100 Years of Hop Chemistry and Its Relevance to Brewing".Journal of the Institute of Brewing.92(1): 32–48.doi:10.1002/j.2050-0416.1986.tb04372.x.ISSN2050-0416.
  45. ^Denis De Keukeleire (2000)."Fundamentals of beer and hop chemistry".Química Nova.23(1): 108–112.doi:10.1590/S0100-40422000000100019.ISSN0100-4042.
  46. ^Ortega-Heras, M.; González-Sanjosé, M.L. (2003). "BEERS | Wort Production". In Benjamin, Caballero (ed.).Encyclopedia of Food Sciences and Nutrition(Second ed.). Academic Press. pp. 429–434.doi:10.1016/B0-12-227055-X/00087-0.ISBN9780122270550.
  47. ^Stevens, Jan F; Page, Jonathan E (1 May 2004). "Xanthohumol and related prenylflavonoids from hops and beer: to your good health!".Phytochemistry.65(10): 1317–1330.Bibcode:2004PChem..65.1317S.doi:10.1016/j.phytochem.2004.04.025.PMID15231405.
  48. ^Milligan, S; Kalita, J; Pocock, V; Heyerick, A; Cooman, L De; Rong, H; Keukeleire, D De (2002)."Oestrogenic activity of the hop phyto-oestrogen, 8-prenylnaringenin".Reproduction.123(2): 235–242.doi:10.1530/rep.0.1230235.PMID11866690.
  49. ^James S. Hough (1991).The Biotechnology of Malting and Brewing.Cambridge University Press.ISBN978-0-521-39553-3.
  50. ^Elizabeth Aguilera (10 September 2008)."Hop harvest yields hip beer for brewer".Denver Post.
  51. ^Kristin Underwood"It's Harvest Time at the Sierra Nevada Brewery"Archived13 September 2011 at theWayback Machine.Treehugger. 6 August 2009. Retrieved 20 March 2011.
  52. ^John Palmer (2006).How to Brew.Boulder, CO: Brewers Publications. pp. 41–44.ISBN978-0-937381-88-5.
  53. ^Hough JS, Briggs DE, Stevens R, Young TW (6 December 2012).Malting and Brewing Science: Volume II Hopped Wort and Beer.Springer. p. 867.ISBN978-1-4615-1799-3.
  54. ^Jan (23 December 2022)."Hops".Beerwiki.Retrieved29 December2022.
  55. ^"The Oxford Companion to Beer Definition of German hops".Craft Beer & Brewing.6 April 2023.Retrieved6 April2023.
  56. ^Stephens, Hollie (18 October 2021)."The Rise of Neomexicanus".Craft Beer & Brewing.Retrieved6 April2023.
  57. ^"Finding Mr. Fuggle: The Largely Mysterious History of England's Two Greatest Hop Varieties".BeerAdvocate.11 April 2016.Retrieved6 April2023.
  58. ^"Brewery History: 121, pp. 94–112".www.breweryhistory.com.Retrieved2 June2017.
  59. ^Capper, Allison; Darby, Peter (24 March 2014)."What makes British Hops Unique in the world of Hop Growing?"(PDF).www.britishhops.org.uk.Archived fromthe original(PDF)on 25 July 2014.Retrieved4 July2014.
  60. ^"History of Hops".British Hop Association.Archived fromthe originalon 30 June 2017.Retrieved19 July2014.
  61. ^"On Trade Preview 2014"(PDF).www.ontrade.co.uk.
  62. ^abcdAndrew Walsh (30 November 2001)."An Investigation into the Purity of Noble Hop Lineage".www.morebeer.com.More Beer; In: Brewing Techniques – Vol. 6, No.2.Retrieved10 March2019.
  63. ^"Hop growers union of the Czech Republic".www.czhops.cz.Czhops.cz.Retrieved20 May2012.
  64. ^"Hop Chemistry: Homebrew Science".www.byo.com.Byo.com. 28 April 2000. Archived fromthe originalon 2 February 2010.Retrieved20 May2012.
  65. ^"9 Perennial Vegetables You Can Plant Once, Harvest Forever… And Never Worry About Again".8 March 2017.torageprepper.com. Archived fromthe originalon 23 April 2021.Retrieved3 June2017.
  66. ^Alexi Duggins (18 May 2015)."'It's like eating a hedgerow': why do hop shoots cost €1,000 a kilo? ".The Guardian.Retrieved3 June2017.
  67. ^Plants for a Future:Humulus lupulusPlants for a Future. Retrieved 4 September 2012.
  68. ^abFranco L, Sánchez C, Bravo R, Rodriguez A, Barriga C, Juánez JC (2012). "The sedative effects of hops (Humulus lupulus), a component of beer, on the activity/rest rhythm".Acta Physiologica Hungarica.99(2): 133–9.doi:10.1556/APhysiol.99.2012.2.6.PMID22849837.
  69. ^Franco L, Sánchez C, Bravo R, Rodríguez AB, Barriga C, Romero E, Cubero J (2012)."The sedative effect of non-alcoholic beer in healthy female nurses".PLOS ONE.7(7): e37290.Bibcode:2012PLoSO...737290F.doi:10.1371/journal.pone.0037290.PMC3399866.PMID22815680.
  70. ^"How Long Do Hops Last? Do Hops Expire? (With Fridge & Freezer Chart) – Learning to Homebrew".12 June 2020.Retrieved28 April2021.
  71. ^Keiler AM, Zierau O, Kretzschmar G (2013)."Hop extracts and hop substances in treatment of menopausal complaints".Planta Med.79(7): 576–9.doi:10.1055/s-0032-1328330.PMID23512496.
  72. ^"Purdue University: Center for New Crops and Plant Products.Humulus lupulusL ".www.hort.purdue.edu.Hort.purdue.edu. 7 January 1998.Retrieved20 May2012.
  73. ^"Animal Poison Control Center. Hops".www.aspca.org.ASPCA.Retrieved20 May2012.
  74. ^Rhode, John (1937).Death in the Hop Fields(First; hardcover ed.). UK: Dodd, Mead & Company.
  75. ^Rhode, John.The Harvest Murder.US.

Further reading

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