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The Role of Genealogy in Hop Substitutions

06/11/2018

A Question of Pedigree

When your favorite hop is nowhere to be found, check out other members of the family to find a suitable alternative.

Ever feel slightly overwhelmed when searching for the right hop for your next brew? To home brewers, reading the labels in the hop section of the local supply store can be like reading the road signs on a German highway. And a commercial brewer’s attempt at replicating a classic style can meet with frustration because of the difficulty in getting the right hop character. Sometimes you pick a hop for a new recipe and find that your local supply store has never heard of it. To make matters worse, some hops are sold under different names in different parts of the world.

Well, it doesn’t have to be as bad as it seems. Knowing a hop’s relatives can help you make sensible substitutions that meet your needs.

Family History

The hop, or Humulus lupulus (lupulus: a little wolf, alluding to the tenacity with which it clings to any support), is native to three major continents: Europe, Asia, and North America. Hops are classified in the plant family of Cannabaceae, which includes the genera Cannabis and Humulus (Figure 1). The genus Humulus includes two major species: Humulus lupulus and Humulus japonicus (an annual Japanese hop that produces few resin glands and is of no value to brewers). Hops grow best between 30° and 52° latitude. Both hop species are dioecious; that is, their sex characteristics manifest as separate male and female plants. Only the female plant produces the hop flowers of brewing and commerce.

At the beginning of this century, scarcely a dozen hop varieties were in use by brewers worldwide; today there are approximately 140 (1). New cultivars proliferated not because brewers demanded new varieties but because growers were trying to keep one step ahead of diseases and pests as well as trying to increase yield. The American hop industry survived Prohibition only to be threatened by the invasion of downy mildew. Hallertauer Mittelfrüh, for example, has been nearly wiped out by verticillium wilt, a soil-borne fungus.

To fill the void left by the decline of Hallertauer Mittelfrüh (Mittelfrüh is German for “middle-early,” which refers to its point of maturation in the season), breeders developed new varieties — Mt. Hood, Ultra, Liberty, and Crystal, to name just a few. Researchers have introduced new varieties that the brewing industry had never even thought possible before the turn of the century — high-alpha hops, high-alpha hops with noble-hop characteristics, and hops without seeds.

Central European ancestry: Hop cultivation dates back over 1000 years in Central Europe. At that time, the geographical separation of regions created natural boundaries and a natural selection process. Pollination was open and left to the wind; female plants received genetic material from the pollen of wild male hops growing nearby.

Growers worked with that process, further selecting the best seeds and rhizomes for future plants. These hops became known by the region from which they came and are now commonly called “land race” varieties (“race” referring to breed or family). Examples of the old land race varieties include Saazer (from the region around what is now the city of Zatec in the Czech Republic), Tettnanger (from the Tettnang region of Germany), Hersbrucker (from the Hersbruck region of Germany), and Hallertauer Mittelfrüh (from the Hallertau region of Germany).

British heritage: By the 14th century, hops were grown in the region now called Belgium and the Netherlands and by the early 1500s were taken across the English Channel by Flemish weavers. Once in England, hops became known by the characteristics of either the cone (Long White, Oval, for example) or the bine or stem (Red Bine, White Bine, for example). During the 19th century, hops were named after the area in which they grew (such as Canterbury, Bramling, and Rodmersham) or by the person who introduced them (Fuggle and Golding, for example).

From 1932 to 1982 the Hops Marketing Board of England assigned English hops into four basic categories: Golding, Golding Varieties, Fuggle, and “other varieties” (which would include new seedlings). Today, the marketing and sale of British hops are governed by the rules of the European Economic Community (EEC) (1).

One of the oldest Golding hop still grown today is Canterbury Golding, sometimes also called Old Golding and now known as part of the East Kent Golding group. This variety was selected from a garden of Canterbury Whitebine by Mr. Golding of Malling around 1790.

The Fuggle hop was first noticed in 1861 as a seedling growing in the garden of George Stace’s house at Horsmonden, Kent, and was introduced by Richard Fuggle in 1875. Fuggle is also grown in the Pacific Northwest and in Europe. The European Fuggle grown in the former Yugoslavia is actually marketed as Styrian (Savinja) Goldings, as a result of a case of mistaken identity in the 1930s.

Other Golding selections include:

  • Petham — selected in the parish of Petham, near Canterbury (date unknown).
  • Bramling — selected in 1865 by a farm balif named Smith on Musgrave Hilton’s farm at Bramling.
  • Rodmersham — selected in 1880 by Robert Mercer, of Rodmersham House, Sittingbourne, from a hop garden at Malling.
  • Cobbs — selected in 1881 by James West from a garden of Canterbury Whitebine on the farm of John Cobb.
  • Amos’s Early Bird — selected in 1887 by Alfred Amos of Wye from a garden of Bramlings.
  • Mathon — selected in 1901, and originally grown in the parish of Mathon, in Worcestershire. It is believed to be the same variety as Canterbury Whitebine and Farnham Whitebine.
  • Eastwell — selected in 1889, and originally grown at Eastwell Park near Ashford, Kent.

Whitbread’s Golding Variety (WGV) is one Golding variety not considered to be a true Golding. It was raised as a seedling in 1911 from a commercial variety of that time, Bate’s Brewer. WGV was found to be tolerant to verticillium wilt and was planted by growers in gardens that were affected by this disease, including parts of Kent where verticillium wilt is prevalent (2).

Pioneer and native stocks meet in the New World: The North American wild hop, Humulus americanus, played a significant role in the development of new hops, especially the high-alpha varieties. The Massachusetts Company introduced English hops to eastern North America in 1629; by 1646, growers were cultivating hops commercially (3). The English hops brought to the New World crossed with wild North American hops over time, and the hop known as Cluster emerged. By the turn of the twentieth century, the majority (about 96%) of the U.S. hop crop was Cluster (4).

Apart from Cluster, the most significant influence in the development of North American hops was the work carried on by Professor E.S. Salmon of Wye College, England. In 1916, seeds collected by Professor Macoun* near Morden in Manitoba, Canada, were sent to Wye College. From these seeds, Salmon obtained a plant he referred to as BB1. Salmon wrote that BB1 “attracted attention in 1925 by the extraordinary richness of its cones … which, when rubbed, became greasy or buttery to the touch” (5). BB1 was involved in crosses that resulted in Brewer’s Gold, Bullion, Northern Brewer (named after brewers in Northern Scotland), and other varieties (see Figure 2).

Several British breweries conducted brewing trials with Brewers Gold in 1933 and 1934. The head brewer of a Kent Brewery said of its dry-hopping test, “On comparing the finished ales it was found that in all ways the C9a (Brewer’s Gold) ale was equal to the Oregon-Saaz ale, and when considering the two ales from the aroma and hop flavor standpoint, there was a delicacy of bouquet in the C9a ale which justified the view that C9a hops could replace an Oregon-Saaz blend with advantage” (6).

In another test, a brewer in Edinburgh† reported, “Brewer’s Gold is too strongly flavored for use at the higher rate (14 oz per barrel) chosen, but the flavor is so pleasant that when used in smaller quantities (10 oz per barrel) this opinion does not hold. … When properly used, i.e. in the ratio of the resin content, and at low hopping rate, C9a is quite suitable for pale ale” (6).

The fact that a North American wild hop resulted in such high-alpha cultivars is surprising considering the findings published in a study for the American Society of Brewing Chemists in 1993 (5). The study essentially said that North American plants with alpha-acid levels above 5% were rare. North American hops are typically high in cohumulone‡ and even higher in colupulone§, which imparts a pungent, unpleasant aroma. By contrast, European land race hops such as Hallertauer, Hersbrucker, Saazer, and Tettnanger are characterized by relatively low content of soft resins (alpha- and beta-acids) — a ratio of almost 1:1 — and are low in cohumulone. Salmon must have selected his BB1 seedling for its unusually high alpha:beta ratio (5).

BB1 died in 1918, but its genetic material lives on in Brewer’s Gold, Bullion, and many cultivars developed from these direct descendants of BB1.

In 1920, the Mosaic disease virus made its appearance in the hop gardens of Wye College. This disease was previously unknown to hops. Salmon discovered a few years later that some varieties, Fuggle among them, were symptomless carriers of Mosaic disease. Because Salmon had been conducting his trials during that time, all the new varieties being tested were symptomless carriers as well.

Modern U.S. cultivars: Although not very popular, Comet was one of the first uses of a North American wild hop for a new U.S. cultivar. Comet was an offspring of a wild male hop that was collected from Logan Canyon, Utah, and crossed with an English hop, Sunshine. The fitst successful U.S. variety came from Dr. Robert Romanko, who in 1968 released an improved Cluster he called Talisman. In 1972, USDA hop researchers at Oregon State University in Corvallis, Oregon, released an improved Fuggle (Fuggle-H) and Cascade.

The first new variety to be released from the USDA breeding program, Cascade was the result of a search for a hop that was resistant to downy mildew disease. It was one seed that was selected out of 7034 in 1956 by S.N. Brooks. The seed originated from a plant obtained by crossing Fuggle with the male Russian Serebrianka. The resulting plant was then crossed with another Fuggle-derived male seedling.

*Professor Macoun wrote in December 1916: “The town of Morden is situated in Southern Manitoba near a range of hills. The wild hop grows along a creek which flows through the town of Morden. Old residents in this town assure me that there has never been any introduction of cultivated hops in this district. The wild variety, growing so abundantly along the creek, was transplanted on the town lots, especially along the fences, and back lanes, to cover unsightly places” (7).

†Scottish and Newcastle breweries were instrumental in growing and naming the variety Northern (Scotland) Brewer (1).

‡Cohumulone exists as a major component of soft resins. High levels of cohumulone produce a harsh unpleasant bitterness and negatively affect head retention. The alpha- and beta-acids are the major components of soft resins (8).

§Colupulone — also part of the soft resins.

Its pedigree breaks down to something like 31% Fuggle, 13% Serebrianka, and 56% unknown due to open pollination, although some speculate that the unknown portion might contain Cluster. With more than half of Cascade’s pedigree unknown, placing it on any family tree is difficult, other than perhaps as a distant cousin to Fuggle. Cascade’s low farnesene content (about 5% of its total oils) is more characteristic of many European hops than of any previous American variety.

Cascade was first harvested in 1968, and the 1969–1970 crops were used by Anheuser-Busch, Coors, and Schaefer & Rheingold breweries. The ultimate success of Cascade can be measured by its current popularity with microbrewers.

Test Tube Babies

The most dramatic new development in the creation of new cultivars was the use of chemically induced tetraploids for use as breeding stock to produce triploids. Most hops are diploids, meaning they have 20 chromosomes. Occasionally through accidents of nature, a tetraploid (polyploid) with 40 chromosomes will develop. A tetraploid can also be induced in the laboratory by treating a plant with a 0.5% solution of the alkaloid colchicine. This tetraploid is then crossed with a diploid male to produce a triploid, which has 30 chromosomes. The resulting plant contains two-thirds of the female parent’s genetic characteristics, it is most likely sterile, and it usually produces seedless cones, which are of greater value to brewers.

This process of genetic manipulation as applied to hops was first published in a report by Wye College, London (3). The advantage of such laboratory-based breeding techniques is that they give researchers much more control over the end result relative to the more traditional techniques of crossbreeding and mass selection.

The first successful triploids were Willamette and its sister Columbia, released in 1976 by Dr. Alfred Haunold of the USDA Research Station in Oregon. These two hops are triploid offspring of Fuggle. Willamette was immediately recognized as having aroma characteristics nearly identical to those of Fuggle.

According to Haunold, triploids represent the highest level of vigor and growth rate in the species (3). The USDA breeding program has been responsible for the development of many new triploid cultivars with emphasis on European aroma characteristics.

In 1989, Haunold released the next triploid, Mt. Hood, a cultivar produced from Hallertauer Mittlefrüh stock. According to its registration data, Mt. Hood produces higher yields in the fields than Hallertauer Mittlefrüh and is moderately resistant to hop downy mildew. Testing in nursery plots near Corvallis and in commercial plots in hop-growing areas of Oregon, Washington, and Idaho between 1985 and 1989 found no symptoms of verticillium wilt (9). A half-sister to Mt. Hood is Ultra, one of the newest releases of an aroma cultivar. Ultra is 66% Hallertauer Mittlefrüh and 17% Saazer.

Current Family Profile

In addition to the breeding programs in Corvallis, Oregon, and Wye College, England, hop research is conducted by commercial and academic interests elsewhere in the United States and England and in Germany, Slovenia, Serbia, the Czech Republic, the Ukraine, New Zealand, Australia, South Africa, India, Japan, and Argentina (3). The majority of world hop production is concentrated in Central Europe and the Pacific Northwest of the United States.* All commercial hop production in the United States occurs in Washington (73%), Oregon (19%), and Idaho (8%) (10). Small quantities are grown in some of the other countries mentioned above; Australia is the most notable area of new hop cultivation.

The good news for brewers is that the desirable traits we look for in hops are not likely to disappear in the near future as Hallertauer nearly did, and new varieties and improved agricultural practices are increasing yields. The tolerance of hops to disease is now within reach of control using modern methods of genetic manipulation (3). Researchers have narrowed down the specific genes for various diseases and have discovered that the genes responsible for the composition of hop essential oils are less complex than previously thought. This discovery makes it possible to retain the desirable essential oil composition and also the low cohumulone content of a Hallertauer and at the same time breed in disease resistance and higher yield.

When choosing a substitution for an unavailable hop, look for a hop that has the closest genetic relationship to the hop that you first wanted. A triploid daughter from a Hallertauer, for example, would be a very close substitution for a true Hallertauer because it carries two-thirds of the genetic material of the female. Some new cultivars even have very closely related parents, and thus also make good substitutions. Liberty, for example, would be a good substitution for a Hallertauer.

Hallertauer Triploid Comparison Test

The folks at Hopunion USA recently mashed 25 gal of wort for a single batch (1.045 SG), which they split into five boiling kettles and in each one used a different hop. In four of the kettles they used the triploids Mt. Hood, Liberty, Ultra, and Crystal, and in a fifth kettle they used domestic Hallertauer. The hopping schedule was three additions during the boil and one addition at the end.

The panelists reported that all of the beers they produced were very nice and showed only subtle differences. Their specific comments are as follows:

                        Liberty             closest to Hallertauer

                     Mt. Hood             slightly more bitter

                           Ultra             a typical Saaz flowery aroma and light hop flavor

                        Crystal             most hop presence, but not necessarily more bitter.

Hopheads that they are at Hopunion, the panelists’ only other comment was that they would have liked to have used more hops or to have tried dry-hopping.

In contrast, the breeding stock that Salmon introduced earlier this century on the female side (BB1) is literally continents apart from the English male hops they were crossed with. Thus, with such different parents the offspring were quite unlike the Goldings; when similar parents are bred, the resulting hops tend to perpetuate their ancestry more closely. The Salmon varieties are diploids, sharing an equal number of male and female chromosomes. Nevertheless, the different traits that were bred into the Salmon varieties make them excellent dual-purpose hops: they have high-alpha percentages for bittering and good aroma characteristics from the English side of the pedigree.

We as brewers have only to recognize that a hop by another name may yet be exactly what we need. A little understanding about the parents’ contributions goes a long way toward making sensible choices.

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