Logo
 
MoreBeer!

Hops in America

11/30/-1

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

*Source: Reference 4.

†1 zentner = 50 kg.

 

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

20–25

Farnesene oil (%)

5-8

10–14

Caryophyllene oil (%)

6–7

5–9

Humulene/caryophyllene ratio

3.1–3.5

3.2–4.0

The Tettnangs. U.S. Tettnang was first released for cultivation in 1970. Apart from the fact that the U.S. variety’s farnesene oil percentage is approximately half that of its German counterpart, the analytical data seem very similar (Table IV).

The Perle group. U.S. Perle was developed in the early 1990s and is grown mainly in Washington. The data in Table V show remarkably similar analytical data for U.S. Perle, its German Hallertauer cousin, and Challenger from England. Challenger is grouped with the others because they share similar characteristics, but they are not linked genetically. Challenger has a higher farnesene content and generally lower cohumulone levels than the others, which results in a softer bitterness.

Table V: A Comparison of U.S. Perle, Hallertauer Perle, and English Challenger Aroma Hops

 

U.S. Perle

Hallertauer Perle

English Challenger

Alpha-acids (% w/w)

6.0–10

6.0–8.0

7.0–9.0

Cohumulone (% alpha-acids)

27-32

25-32

20-25

Beta acids (% w/w)

4.0–5.0

3.0–5.0

4.0–5.0

Alpha/beta ratio

1.5–2.5

1.2–1.8

1.8–2.2

Alpha stability (% after 6 months)

80–85

75–85

70–85

Total oil (% v/w)

0.7–1.0

0.8–1.3

1.0–1.7

Myrcene oil (%)

45–55

15–25

30–42

Humulene oil (%)

28–33

30–36

25–32

Farnesene oil (%)

<1%

<1%

1–3

Caryophyllene oil (%)

9–12

8–10

8–10

Humulene/caryophyllene ratio

2.7–3.3

3.0–3.6

3.0–3.3

 

Table VI: A Comparison of U.S. and Czech Saaz Aroma Hops

 

U.S. Saaz

Czech Saaz

Alpha-acids (% w/w)

2.5–4.5

3.0–4.0

Cohumulone (% alpha-acids)

24–28

24–28

Beta-acids (%)

3.0–4.0

3.0–4.0

Alpha/beta ratio

0.7–1.1

0.8–1.2

Alpha stability (% after 6 months)

45–55

45–55

Total oil (% v/w)

0.4–0.6

0.4–0.7

Myrcene oil (%)

15–25

20–25

Humulene oil (%)

25–40

40–45

Farnesene oil (%)

10–15

11–15

Caryophyllene oil (%)

8–12

10–12

Humulene/caryophyllene ratio

3.2–3.6

3.5–4.0

Saaz hops. U.S. Saaz hops, first grown in Washington in 1991, are still in their salad days, and therefore the analytical data need to be viewed cautiously (Table VI). All the signs suggest, however, that Saaz should be another successful American-grown variety; the analytical data between U.S. and Czech Saaz are nearly identical, except for much lower myrcene for the U.S. Saaz.

High-alpha, or bittering varieties (6): Cluster. The “traditional” U.S. alpha hop, selected Cluster clones have been propagated over the past 100 years to improve yields. In the past 20 years, Cluster, as a percentage of the total American crop, has dropped from 66.3% to 13.8%, and much of its acreage has been replaced by Galena, Nugget, and Chinook. It is now better classified as a dual-purpose hop.

Galena, Nugget, and Chinook. The data on these three major American high-alpha varieties (Table VII) compared with those of their European equivalents (German Northern Brewer and Hallertauer Magnum, English Wye Target, and Super Sryrians [Slovenian Aurora]) show higher alpha-acid contents for the American varieties than for any of the European varieties. Galena is unique in its high beta-acid content and, therefore, its low alpha/beta ratio. Galena also has a relatively low oil and caryophyllene content.

Table VII: A Comparison of U.S. and European Bittering Hops

 

U.S. varieties

 

European varieties

 

Galena

Nugget

Chinook

Wye Target

Northern Brewer

Hallertauer Magnum

Super Styrians

Alpha-acids (% w/w)

12–14

12–14

12–14

10–13

7–9

11–13

8–11

Cohumulone (% alpha-acids)

38–42

24–30

29–34

30–38

28–33

25–30

22–27

Beta-acids (%)

7–9

4–6

3–4

4–6

3–5

4–6

3–5

Alpha/beta ratio

1.4–1.8

2.8–3.5

3.5–4.2

2.0–2.4

2.1–2.5

2.5–3.0

1.9–2.3

Alpha stability (% after 6 months)

75–80

70–80

65–70

45–55

70–80

65–75

Total oil (% v/w)

0.7–1.4

1.3–2.3

1.5–2.5

1.6–2.6

1.4–2.0

1.8–2.4

1.0–1.5

Myrcene oil (%)

55–60

51–59

35–40

45–55

30–38

30–40

20–25

Humulene oil (%)

10–15

12–22

20–25

20–30

25–30

30–40

25–30

Farnesene oil (%)

<1.0

<1.0

<1.0

<1.0

<1.0

<1.0

8–11

Caryophyllene oil (%)

3–5

7–10

9–11

8–11

9–12

9–11

8–11

Humulene/caryophyllene ratio

2.0–3.0

2.0–2.4

2.1–2.4

2.1–2.5

3.2–3.6

3.0–4.0

3.0–4.0

                 

The data suggest that Galena and Nugget have equally good levels of alpha during storage, but over a 12-month cold storage at 24 °F (–4 °C), Nugget is the most stable (Figure 2), followed by Galena. Chinook is the least stable of the three (8).

Hop Products Produced in the United States

Hop products are produced similarly in the United States and overseas. The following information (9) describes the manufacturing procedures but provides site information specific only to the United States.

Hop pellets: Hop pellets are divided into three types: Type 90, Type 45, and isomerized pellets.

Type 90. Type 90 pellets are the most common form of hop pellet. They are simply whole hops ground, blended, and pelletized by extrusion.

Six facilities make Type 90 pellets in the United States in the Yakima Valley, and a seventh is scheduled to open next year. Sunrise (Sunnyside, Washington) may well be the largest facility in the world this crop year. Each pelletizing facility varies slightly in its equipment. The quality of a pellet is determined by a plant’s ability to blend the powder before pelletizing, its pellet dyes, and the mill. The gas flushing and vacuum packaging operations and the condition of the sachet and cartons are also important factors.

Type 45. Type 45 pellets, also called enriched pellets, are mechanically concentrated pellets. They derive their name from the fact that they contain 45% of the original weight of the hops. Type 45 pellets have an alpha-acid content nearly double that of the original hops. The hops are milled and screened at low temperatures (–31 °F [–35 °C]) to overcome the inherent stickiness of lupulin glands. The process yields more than 95% of the original lupulin in about 45–50% of the original weight. Customers who are situated far away from the pellet shipping sites benefit from Type 45 pellets because of their reduced storage volume and, hence, reduced transport cost.

Two U.S. pelleting facilities produce Type 45 pellets. The standards for judging Type 45 pellet quality are the same as those that apply to Type 90 pellets.

Isomerized pellets, or modified pellets. In 1978, Bert Grant patented a process for improving the isomerization rate of pellets during the wort boil. The patent consists of adding 1–3% magnesium oxide to the powdered Type 90 hops before pelletization, which yields a stabilized pellet. By moderately heating these pellets in their final packaging, the alpha-acids are converted into iso-alpha-acids to produce isomerized pellets.

These pellets can be added at any stage of the wort boil, significantly increasing utilization from around 35–40% to over 60% and decreasing energy needs because of shorter boiling times. Isomerized pellets are the most economical form of bittering available to the brewer (Figure 3). They do not require cold storage to preserve bittering value, though cool storage does enhance their ability to retain the flavor elements of the original hops. Two facilities in the Yakima Valley produce this type of pellet.

Interestingly, no hop plugs are produced in the United States because they are used primarily in cask-conditioned beer, which until recently, was rarely made by U.S. microbrewers.

Hop extracts: Three types of extracts are produced in the United States: hexane extract, liquid carbon dioxide extract, and supercritical carbon dioxide extract.

Hexane extract. Although hexane is a cost-effective solvent for the production of extracts, consumer desire for a safer solvent encouraged the Brewing Research Foundation International in the United Kingdom in 1970 to concentrate on developing the use of liquid carbon dioxide extract. Only one extract plant in Yakima Valley uses hexane.

Liquid carbon dioxide extract. This product is clean, containing very small amounts of polyphenolic material and no hard resins. Polyphenols contribute to haze formation in beer, so less polyphenolic material produces fewer haze problems. The final extract contains 30–60% alpha-acid. Two plants in the United States produce liquid carbon dioxide extract.

Supercritical carbon dioxide extract. The composition of supercritical carbon dioxide extract can be varied more than that of liquid carbon dioxide extract because processing plants can apply various pressure and temperature combinations. Customers, particularly large breweries, therefore gain more choice in the type and characteristic of hop extract they order. The alpha-acid range of the final extract is between 25 and 63%. The percentage is dependent on the alpha-acids in the original hops, but hops quality can influence the extraction yield. Three plants in the United States produce supercritical carbon dioxide extract.

Tapping Those Alpha-Acids — The Process of Extraction

Solvent Extraction

Hexane is the solvent used by the U.S. plant; European manufacturers use ethanol and methylene chloride.

·   Whole hops arrive at the extracting plant in bales weighing approximately 200 lb.

·   The bale cloth is removed and the bales are fed into the bale breaker, which breaks up the slightly compressed bale into individual cones.

In addition, extraneous material (metal, clay, stone, etc.) is removed by magnetic separators and pneumatic conveyors to avoid damage to the equipment and to reduce the fire hazard.

·   The hops are pneumatically or mechanically transported to an extractor (belt or carousel) and solvent is added.

·   The used hops are discarded and the solvent and alpha-acid solution is transported to evaporators, which separate the solvent from the alpha-acids by evaporation (heat).

·   The solvent is returned to the solvent tank for reuse.

·   The extract is collected in a tank and diluted with syrups to obtain a particular alpha-acid strength (20, 30, or 40%). From this holding tank the extract is fed to a canning machine and packaged in 1-, 2-, 5-, or 10-kg cans.

·   The cans are transported to the palletizing machine to prepare for storage or delivery.

·   Because of the extreme stability of extracts, they can be stored and transported without refrigeration.

Carbon Dioxide Extraction

·   Whole hops arrive at the extract plant in bales weighing approximately 200 lb.

·   The bale cloth is removed and the bales are fed into the bale breaker, which breaks up the slightly compressed bale into individual cones. In addition, extraneous material (metal, clay, stone, etc.) is removed by magnetic separators and pneumatic conveyors to avoid damage to the equipment and to reduce the fire hazard.

·   The mill grinds the hops into a powder, which is transported to a pellet press, where they are pelletized for ease of storage and handling.

·   Pellets can be stored before extraction either in large 1,000–5,000 lb bags, or, preferably, in large 170-kg sachets that fit into cartons.

·   For more efficient extraction, the pellets are fed through a mill again to grind them back into powder.

·   The hop powder is pneumatically transported to the extractors, and carbon dioxide is added to extract the alpha-acids.

·   The mixture of alpha-acids and carbon dioxide are fed into an evaporator to separate the carbon dioxide and alpha-acids.

·   From the evaporator the concentrated alpha-acids — 27–55% in the supercritical carbon dioxide extract and 30–60% in the liquid carbon dioxide extract — are fed into a blender. The liquid carbon dioxide is cleaner because it contains no hard resins or chlorophylls and very few polyphenolic compounds. The composition of supercritical carbon dioxide extract, however, can be varied more than that of the liquid carbon dioxide extract.

·   From the blender, the extract is weighed and fed into a canner (normally 1-kg cans, but these can be larger), and the cans are transported to the palletizer machine.

·   Because of the extreme stability of extracts, they can be stored and transported without refrigeration.

Other products: Isomerized resin extract (IRE), reduced isohumulone products, and hop oils. These further “downstream” hop products allow brewers greater flexibility and control over some aspects of beer quality. They are relatively “sophisticated” and expensive products in the brewer’s total available inventory of raw materials. Four plants in the United States produce these products.

Hops into the Future

The U.S. hop industry will lead world hop production in the future because of an experimental attitude, strong research and development support, and optimum climactic conditions. The microbrewery industry has played a part in this expansion, and will continue to influence the U.S. hop industry’s expansion in the world market.

All contents copyright 2019 by MoreFlavor Inc. All rights reserved. No part of this document or the related files may be reproduced or transmitted in any form, by any means (electronic, photocopying, recording, or otherwise) without the prior written permission of the publisher.