The Story of Hops Part Two: Breeding meets Science

By Mark Bowers

(continuation of The Story of Hops Part One)

From Roadside Attraction to Mainstream Crop

With the expansion of commercial beer in the 1800s, especially the later part of the century, hops too became big business. However, farming hops still was a risky proposition for farmers. For example, in the 1800s a hop grower could only expect a full crop once in about 10-20 years. Sometimes the harvest could vary from one year to the next by nearly 10 times.

As a result of the importance of hops in beer coupled with the many scientific advances in the 19th century, in the early 20th century, most of the major hop growing regions in the world established breeding research centers. For example, Wye College in the UK in 1904 established a hop breeding program and within a couple of years hired Ernest S. Salmon whose work greatly influenced later hop researchers as well as modern hop varieties. In addition, the influential hop researcher Karel Osvald started a Czech hop breeding program in 1925 and shortly thereafter the Hop Research Center in Hull Germany in 1926 opened. Plus the US Department of Agriculture established a hop program in Oregon in 1930. Other countries followed with their programs too, including countries not normally associated with beer like Mexico, South Africa and Peru plus Australia and New Zealand.

It should be no surprise that researchers at these institutions are quite aware of and use all the modern scientific instruments and techniques available to scientists today. This is especially true of biological advancements in genetic research.

One early scientific revelation was the discovery of the bittering compounds in hops that are not only responsible for beer’s bitter flavor but also its preservative properties. The major chemical compounds responsible for the bitterness are called alpha acids. There are three of them of major importance and although they are not very bitter or soluble in beer themselves they become so when boiled in wort for a while. The chemical process of the transformation from insoluble non bitter to soluble bitter compounds is isomerization. That is for those of you who haven’t had many chemistry courses or forgot them, is where the atoms in the chemical compound are the same ones and number but change their positions to form different molecular shapes or structures. Each of the three alpha acids isomerize in boiling wort to yield two isomers, surprisingly referred to as iso alpha acids.

Brewers are very concerned with the amount of iso alpha acids in beer as this is the way bitterness in a beer is measured. The measurement of the total amount of the 6 iso alpha acids is expressed as ppm (parts per million or milligrams per liter³) in a beer. This number is also referred to as IBUs (pronounced “eye-bee-yous”), which stands for international bittering units. Many brewers list their beer’s IBUs on their labels. 

As this talk of IBUs is kind of academic, let’s try to give it something to relate to. For example, the common American macro lager, think BMC (Busch, Millers, Coors), comes in at about 8 IBUs. It’s generally thought that the threshold of detecting bitterness in a drink is about 5 IBUs for most people. So these macro lagers are definitely on the low end of bitterness for a beer. 

Here is a table with some more IBU values for some commercial beers including several from Aeronaut:

So as a general rule of thumb, 5-15 IBUs low bitterness, 15-25 IBUs moderate bitterness, 25-50 IBUs definitively bitter, >55 IBUs quite bitter. 100 IBUs or more, palate wrecking

The amount of alpha acids in a given lot or batch of hops is given as a percentage of the total weight of the hops. Typical values range from about 2% for many noble hops like Saaz to well over 20% for some newer, high alpha varieties like Columbus. So to make a bitter hoppy brew like say Stone’s IPA, it would take 10 times more Saaz hops than Columbus. For a 10 barrel batch (310 gal) it would take about 4 lbs of a high alpha batch of Columbus or closer to 50 lbs for a low alpha batch of Saaz. Thats a huge difference in the amount of hop material in a brew!

BB1, Fuggle and the Hop Revolution 

BB1? Sounds like a ’droid from Star Wars. Responsible for a revolution in the world of hops and beer? Yes, that’s right. And it gets some help from the hop of my youth, Fuggle.

In what was likely a cold and wet spring day in 1917, Professor Salmon planted a female hop in the first position of row BB in his hop nursery of Wye College. This hop plant was referred to as BB1 in his research. Although BB1 died in the winter of 1918-1919, apparently unable to adapt to its transplanted environment, hundreds of its offspring in the form of seeds did survive and were used in research to develop new hop varieties. 

What’s so special about the female hop plant BB1? It was grown from a cutting of a wild hop plant sent to Salmon from Professor W. T. Macoun of Morden, a town in southern Manitoba, Canada.4 And where does Fuggle enter in? The offspring of BB1 were likely the result of a cross pollination by a nearby male hop plant, which was quite likely a Fuggle (or maybe a Goldings).

Salmon was very clear in what his research group’s goal was. He specifically stated in a paper that his main objective was to mate the high alpha acid content of American hops with the aroma of European hops. His (and others too) goal undoubtedly led the decades long development of high alpha acid hops. Early on in the development of hops, how much a given hop had in bitter producing alpha acids was quite important. It became almost the only criteria important to the major brewing companies in the 20th century. Hence the search for high alpha acid hops. As it costs about the same to grow and produce high alpha acid hops as it does low alpha acid hops, brewers would save a lot of money by purchasing high alpha acid hops. Great for the brewers. Not so good for the farmers.

The offspring of BB1 led directly to two very important hop varieties — Brewer’s Gold and Bullion — both of which were released in the 1930s. These hops had alpha acids in the 8-10% range, significantly higher than the typical European hops. Before long these hops became some of the most popular hops in the US by the mid 20th century or so. Unfortunately, British brewers were not enamored with either of these two hops. However, Brewer’s Gold did find some success in Germany where it was routinely planted for a number of years.

The search for more and higher alpha acid hops continued throughout most of the 1900s. Many  of the high alpha hops could trace at least some of its DNA back to BB1. Clearly, this hop research was driven by the major breweries in their endless goal to improve efficiencies and reduce costs as much as possible. However, one unintended outcome of this search was the rise of new hops with differing aroma/flavor attributes that would play a major role early in America’s craft brewing revolution.

By many accounts, craft breweries got their start in the US at about 1980. Two very early influential breweries that led the way were Anchor Brewing in San Francisco and Sierra Nevada in Chico, both in California. Anchor had actually been around since 1876, but at the time Fritz Maytag bought it, in 1965, it was just producing a handful of kegs per month. It was a long road to keep the brewery afloat and to make it profitable, an effort that took more than a decade. At this time hops were just another part of the equation to making beer and selling it. However, Maytag from the beginning saw craft beer as a return to beer that tasted special, echoing what was occurring at that time with wine and the good food movement. As such Maytag was interested in producing an ale, a special ale, that reminded him of Real Ales, like Timothy Taylor’s Landlord in Yorkshire, England, which he had tasted on a trip to the UK in researching beer. Maytag was also inspired by the last commercial IPA made in the US — Ballantine’s IPA made with Bullion hops. He wanted to make an ale commemorating the 200th anniversary of Paul Revere’s 1775 ride.

Experimental Hop 56013

This was the number given to an experimental hop that was a cross between a Fuggle hop and a Russian hop in 1956 developed by the USDA hop breeding program. However, there was little interest in the hop until a small amount of it was grown by John Segal in 1970 who became enamored with it. The hop was released commercially in early 1972 and sometime after that Segal introduced it to his friend Maytag who used it Anchor’s commemorative Liberty Ale in June, 1975, by some accounts the first craft IPA in America. Although not labeled an IPA, it had a citrusy, grapefruit heady aroma and flavor from the generously dry hopped ale. And it had a substantial bitterness coming in at ~40 IBUs. This beer was a revelation to aspiring craft brewers5

By this time the hop had been renamed Cascade, in honor of the mountain range with that name. Ken Grossman used Cascade in his Sierra Nevada Pale Ale. Soon after, the Cascade hop was featured in most pale ales and IPAs from the burgeoning craft beer brewers. Eventually Cascade became the most popular hop grown in the US for over 10 years.

Sierra Nevada’s Iconic American Pale Ale brewed with Cascade Hops (Image, SteveR, Public domain, via Wikimedia Commons)

Hop ’Splosion

After Cascade helped fuel the start of the IPA revolution, other hops soon followed, starting as a trickle and then becoming a near steady stream. Centennial, whose ancestors, you guessed it, included BB1, was known as super Cascade and was featured in Sierra Nevada’s seasonal Celebration Ale along with Cascade and Chinook (another descendent of BB1), released in 1981.

More fruity hops were released throughout the coming decades as customers, brewers and hop breeders clamored for more fruity and not just citrusy, but tropical fruit, berries, stone fruit, melons and eventually way out flavors like coconut, mint, dill, oak and even bourbon. Popular hops that are derived from BB1 include two of my favorites, Citra and Mosaic, plus Nugget, Azacca, Calypso, Strata, Cashmere and probably Columbus. Many other hops are likely to include BB1 or Fuggle too as parents, but many commercial hop breeders are loath to reveal the lineage of their hops. Most of the fruity in demand hops from Australia and New Zealand also have some wild American hop ancestry as well.

Author Standing in Front of a Huge Pile of Fresh Citra Hops in Yakima Valley

These modern hops are the major reason IPAs have become the single most popular beer style by a long shot. Although hops, mostly due to their bitterness, are important in essentially all beer styles, modern aromatic and flavorful hops are the essential ingredient of new IPAs that include West Coast IPAs, Black IPAs, New England IPAs, Fruit IPAs, Milk Shake IPAs, Brut IPAs and more.

Mark Bowers is the Brewmaster at Aeronaut. The views and opinions expressed on this web site are solely those of the original author, and they do not necessarily represent those of Aeronaut Brewing Co.


3. When describing the attributes of beer as hoppy, this oftens leads to confusion. That is a beer’s bitterness is often described as hoppy and so are the non-bitterness flavors of beer that include, for example spicey, herbal, fruity, etc. Until recently, the only effective traditional way of getting more hop flavor also included more bitterness, so the two attributes were essentially linked in many drinkers’ minds.

4. It’s a bit ironic that the town of Morden is less than 80 miles away from Winnipeg, home to the original Drewrys brewery. And that Drewerys used Fuggle hops in their lager although clearly at the time I heard about Fuggles in Drewerys, the major hops used in American lagers were likely Brewers Gold, which had as one of its ancestor’s genetic material from Professor Salmon’s BB1, originally from Morden. 

5. Although I was not able to try the original Anchor Liberty Ale, I did taste it’s brethren, Anchor Christmas Ale in 1979. Anchor originally intended Liberty Ale to be a once only release. However, the beer was so popular they released it as their seasonal Christmas Ale in late 1975 and eventually renamed it back to Liberty Ale in 1983 as the beer became a standard in their lineup. This beer is the one that hooked me on citrusy, piney hops!


Stan Hieronymus, For the Love of Hops: The Practical Guide to Aroma, Bitterness and the Culture of Hops (Boulder, Colorado, Brewers Publication, 2012)

Tom Acitelli, Audacity of Hops (Chicago Illinois, Chicago Review Press, 2013)

Mitch Steele, IPA: Brewing Techniques, Recipes and the Evolution of India Pale Ale (Boulder, Colorado, Brewers Publication, 2012)

Martyn Cornell (November 20, 2009), “A short history of hops” Zythophile, retrieved from

Mark Bowers (April 2, 2020), “History of the India Pale Ale” , Aeronaut Blog, retrieved from

Mark Bowers (April 18, 2020), “History of the New England IPA”, Aeronaut Blog, retrieved from

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