Hops in America
A 20-Year Overview
by Ing. Gerard W. Ch. Lemmens (Brewing Techniques - Vol. 4, No.6)
A review of hop varieties currently grown in the United States shows a competitive, diverse, and growing U.S. hops industry.
Because of extensive favorable growing conditions, the United States has established a firm hold in the world hops market, offering American hops with distinct qualities. This article analyzes the varieties grown today in the United States compated with the well-known European cultivars and also reviews the changes in the profile of U.S. hop production over the past 20 years. Because of the many innovations made in the hops industry in recent years, no presentation about the U.S. hops industry would be complete without touching on the production of pellets, extracts, and other hop products.
The Roots of an American Industry
Hops have been grown in the United States for much longer than most people realize. They were first planted in about 1629 in the Boston area by English settlers and in New Amsterdam (New York) by Dutch settlers. Although the Dutch grew some hops, they preferred to import hops rather than grow them in America.
In the 19th century, as settlers moved west, hops moved with them from the East Coast via Wisconsin (a large producer of German beer) to the West Coast, first to California, Oregon (1850), and then western Washington (1865). Since an 1887 mite infestation in Puyallup, Washington (1), the Yakima Valley to the east, with its optimal climactic conditions for growing hops, has become the largest producer of hops in the United States, followed by Oregon and Idaho. The demise of the California hops industry was mostly due to moisture, which led to mold and pests.
Hop production has progressed so well in the United States, particularly in Washington state, that the total amount of alpha-acids, total weight of hops, and per-hectare yield in 1994 and 1995 were higher overall in the United States than in the other leading world hop producing country, Germany (Table I). Germany, however, still devotes more land to hops, though U.S. acreage has grown significantly over the past 20 years.
Much of the success of American hops can be attributed to climate. Washington state, in particular the Yakima Valley, produces 80% of U.S. hops. The valley, surrounded by the Cascade Mountains, has high daytime summer temperatures of about 95 °F (35 °C) with low humidity (38% relative humidity). These conditions, together with ample irrigation (750–1,000 mm of water applied during the spring and summer), produce 10–30% higher yields compared with European hop farms. The rainfall in the hop-growing region is only 40 mm during the growing season, which makes it resistant to hop diseases and pests (2). Consequently, less pesticides are applied in the Yakima Valley, and the hops are of such high quality, their appearance need no improvement from sulfur bleaching during the drying process.
Increased Production and a Changing Mix of Varieties
Great changes occurred in the U.S. hop industry between 1975 and 1995 (Figure 1). Overall, the total area of production increased by 33% in this 20-year period, from 13,140 to 17,478 hectares. The number of varieties grown and the relative production of aroma versus bitter hops have increased significantly (3).
Aroma hops: Over the past 20 years, the percentage of acreage devoted to production of aroma hops has increased significantly. Whereas aroma hop production accounted for only 22% of overall production in 1975, aroma hops now represent 37% of all U.S. hops produced. Twenty years ago, only two aroma varieties, Cascade and Fuggle hops, represented over 99% of the aroma crop. Since that time, many other varieties have been introduced, with Willamette, Tettnanger, Mt. Hood, and Cascade hops making up almost 75% of 1995 aroma acreage. Willamette hops alone accounted for 38% of aroma hop production in 1995, or 14% of total production. The expansion in aroma hop varieties can be attributed to increased export trade and the demands of both the large commercial and microbreweries; the industrial-sized breweries because they wanted easier access to European aroma types in the United States, and microbreweries because they wanted to brew with a greater variety of hops in their beer. Overall, the increase in Willamette, compared with the decline in Fuggles, may be attributed to better yields and slightly better alpha-acid levels.
Bitter, or high-alpha varieties: Growth in the aroma portion of the market has meant a decline in bittering hop production as a percentage of overall production (from 78% in 1975 to 63% in 1995). What is most interesting, however, is that the hop varieties that make up the bittering harvest have changed. In 1975, Cluster was the most widely grown variety in the United States, representing 85% of the bittering acreage (66% of total acreage). At that time, Cluster was such a dominant hop that it and the aroma variety Cascade together represented nearly 80% of total U.S. hop production. In 1995, however, Cluster accounted for only 22% of bittering acreage and 13.8% of total acreage, while Galena and Nugget accounted for about 63% of the bittering acreage and almost 40% of the total U.S. production. Since Clusters and varieties with similar alpha-acid levels were first introduced, researchers have developed other varieties with higher alpha-acids that are, hence, more economical. Cluster, incidentally, would now probably be put in the class of dual-purpose varieries that have an alpha-acid content of approximately 8–9% and acceptable aroma contributions.
A Comparison of U.S. and European Varieties
Hops of the same name (variety) can differ significantly depending on where they are grown. To complicate matters, each hop-growing country or region grows a mix of hops based on local climactic and market conditions. Analytical data for similar varieties of hops grown in the United States and elsewhere show distinct differences in the production of acids and oils from country to country (Tables II–VII; data from references 4–5).
| Table I: Hop Production n the United States, Germany, and the World, 1993–1995* | |||
|
| Crop Year | ||
|
| 1993 | 1994 | 1995 |
| Hop production (zentners)† |
|
|
|
| United States | 690,375 (25.0%) | 676,767 (28.4%) | 714,869 (27.7%) |
| Germany | 849,134 (30.7%) | 568,811 (23.9%) | 694,004 (26.9%) |
| World | 2,763,313 | 2,377,756 | 2,572,802 |
| Total alpha production (million kg) |
|
|
|
| United States | 3.523 (37.1%) | 3.214(42.8%) | 3.351 (39.0%) |
| Germany | 2.708 (28.5%) | 1.509 (14.1%) | 1.814(21.1%) |
| World | 9.501 | 7.498 | 8.584 |
| Hop yield (zentners/hectare) |
|
|
|
| United States | 39.6 (+33.3%) | 39.4 (+47.5%) | 40.9 (+42.5%) |
| Germany | 36.9 (+24.0%) | 25.9 (–3.0%) | 31.7 (+10.5%) |
| World | 29.7 | 26.7 | 28.7 |
| Hop hectarage |
|
|
|
| United States | 17,564 (18.9%) | 17,164 (19.3%) | 17,478 (19.5%) |
| Germany | 23,017 (24.8%) | 21,930 (24.7%) | 21,885 (24.4%) |
| World | 92,916 | 88,972 | 89,569 |
| †1 zentner = 50 kg. | |||
*Source: Reference 4.
| Table II: A Comparison of U.S. and European Aroma Hops* | ||||||
|
| U.S. Varieties |
| European Varieties | |||
|
| Cascade | Willamette | U.S. Fuggle | English Fuggle | Styrian Goldings | |
| Alpha-acids (% w/w) | 4.0–7.0 | 4.0–7.0 | 4.0–6.0 | 4.0–6.0 | 4.0–6.0 | |
| Cohumulone (% alpha-acid) | 33–40 | 30–35 | 25–32 | 23–30 | 25–30 | |
| Beta-acids (% w/w) | 4.0–7.0 | 3.0–4.0 | 2.0–3.0 | 2.0–3.0 | 2.0–3.0 | |
| Alpha/beta ratio | 0.8–1.3 | 1.2–1.7 | 1.5–2.5 | 1.5–2.5 | 1.5–2.5 | |
| Alpha stability (% after 6 months) | 48–52 | 60–65 | 60–65 | 70–80 | 65–80 | |
| Total oil (% v/w) | 0.7–1.5 | 0.8–1.5 | 0.6–1.2 | 0.7–1.4 | 0.5–1.0 | |
| Myrcene oil (%) | 45–60 | 45–55 | 40–50 | 24–28 | 27–33 | |
| Humulene oil (%) | 10–16 | 20–30 | 20–27 | 35–40 | 34–38 | |
| Farnesene oil (%) | 4–8 | 5–8 | 4–6 | 5–7 | 2–5 | |
| Caryophyllene oil (%) | 3–6 | 7–8 | 6–10 | 11–13 | 9–11 | |
| | ||||||
*Source: Reference 6.
| Table III. U.S. Mt. Hood and Liberty Hops Compared with German Aroma Hops | |||||
|
| U.S. Varieties |
| German Varieties | ||
|
| Mt. Hood | Liberty | Hallertauer Hersbrucker | Hallertauer Mittelfrüh | |
| Alpha-acids (% w/w) | 4.0–7.7 | 3.0–6.0 | 3.0–5.0 | 3.0–6.0 | |
| Cohumulone (% alpha-acids) | 22–26 | 24–30 | 20–28 | 18–26 | |
| Beta-acids (% w/w) | 4.0–7.9 | 3.0–4.0 | 4.0–6.0 | 3.0–5.0 | |
| Alpha/beta ratio | 0.8–1.4 | 1.0–1.4 | 0.7–1.0 | 0.6–1.2 | |
| Alpha stability (% after 6 months) | 40–55 | 35–55 | 55–65 | 50–60 | |
| Total oil (% v/w) | 1.0–1.3 | 0.6–1.2 | 0.7–1.3 | 0.7–1.3 | |
| Myrcene oil (%) | 40–55 | 30–40 | 12–20 | 15–25 | |
| Humulene oil (%) | 15–38 | 35–40 | 20–30 | 35–45 | |
| Farnesene oil (%) | <1.0 | <1.0 | <1.0 | <1.0 | |
| Caryophyllene oil (%) | 7–13 | 9–12 | 9–14 | 9–14 | |
| Humulene/caryophyllene ratio | 2.2–2.7 | 3.3–3.7 | 1.8–2.8 | 3.5–4.0 | |
First, though, it is important to separate the differences in the cultivated plants from differences that result from processing techniques. Unless specifically requested otherwise, U.S. hop growers generally place their hops in 24 °F (–4 °C) cold storage immediately after harvest to keep their aroma and alpha qualities at their best. The refrigeration process, however, also keeps myrcene content high, which is apparent in Tables II—VII. Myrcene is considered by some to be disadvantageous because it can impart harsh or grassy flavots. In my opinion, however, the myrcene content is not that important, because such a volatile compound readily evaporates during the boiling process or during hop processing into pellets and extract.
Lower moisture content gives American hops an economic advantage over European hops; higher moisture content correlates with alpha-acid loss during stotage. European Community laws allows a moistute level as high as 12%.
| Methods of Analysis for Tables II–VII |
| Alpha- and beta-acid content were calculated using ASBC spectrophotometric methods. Cohumulone content, expressed at the percent of alpha-acids, was figured using ASBC high performance liquid chromatography (HPLC). “Alpha storage stability” refers to the alpha-acid content after six months storage at room temperature. Oil content was determined from gas–liquid chromatography after a 4-hour boil of 100 g of hops in 3.5 L water (6). |
Aroma hops: The Fuggle group (6). The Willamette variety, a triploid seedling of the Fuggle, was developed in Oregon in the late 1970s and is now grown in Washington and Oregon as a Fuggle replacement. Cascade hops were bred in the United States from a Fuggle seedling and released in 1972 (5). Cascades have lost their popularity among the large commercial brewers, however, in the past 20 years. Production of Fuggle also has dramatically declined because Willamette’s yields are so much better.
When we compare these three American aroma varieties to theif European equivalents (Table II), Fuggles from England and Styrian Goldings from the Slovenian Republic, we notice great similarities with all except Cascade. Cascade shows higher cohumulone content, more beta-acids, lower alpha/beta ratios, less alpha-storage stability, and lower percentages of humulene and caryophyllene. As already mentioned, all three Ametican aroma varieties show a much higher myrcene percentage because of the cold stotage to which U.S. hops are exposed (7).
The Mittelfrüh group. Table III compares the two U.S. hops Mt. Hood and Liberty (which were derived from Hallertauer Mittelfrüh) with their European counterparts, Mittelfrüh and Hersbrucker.
Mt. Hood, a tetraploid seedling developed from Mittelfrüh in the late 1980s in Oregon, is now grown in Oregon and Washington. Mt. Hood shows characteristics similar to Hersbrucker and Hallertauer, but the percentage of humulene oil is closer to that of Hersbrucker.
Liberty is a triploid seedling of Mittelfrüh. It was released for general cultivation in 1991 and is planted mostly in Washington. Liberty shows great similarities analytically to Mittelfrüh. Its humulene content, however, is a little lower than that of Mittelfrüh.
| Table IV: A Comparison of U.S. and Tettnanger Tettnang Aroma Hops | ||
|
| U.S. Tettnang | Tettnanger Tettnang |
| Alpha-acids (% w/w) | 4.0-5.0 | 3.0–5.0 |
| Cohumulone (% alpha-acid) | 20-25 | 23–29 |
| Beta-acids (% w/w) | 3.0–5.0 | 3.0–5.0 |
| Alpha/beta ratio | 1.0-1.3 | 1.0–1.2 |
| Alpha stability (% after 6 months) | 55-60 | 55–60 |
| Total oil (% v/w) | 0.4-0.8 | 0.6–1.0 |
| Myrcene oil (%) | 35–45 | 20–26 |
| Humulene oil (%) | 18-23 |
|