Monday, March 15, 2010

Interview with Dr. Shaun Townsend

Breeding a Bold New World of Aroma Hops

The quest to breed more desirable aroma hops, aromas and flavor, oddly enough, has never really begun. While breeders like Dr. Al have hit home runs on crafting hop cultivars with more alpha, or higher yields, or disease resistance, few if any public breeding programs have made new and better aroma oils their holy grail.

Until now. As we’ve reported, Indie Hops has sponsored a breeding and research program at Oregon State University which, for the first time, targets aroma hops. I spoke with Dr. Shaun Townsend, hops geneticist, about the new program that he’s pioneering along, along with his colleague Dr. Tom Shellhammer, a hop chemist.

Is there a Super Aroma Hop Profile?

The short answer, according to Shaun, is no. We can talk all day about total oils and specific oil compounds. But , but nobody really knows – largely because the research investment historically has been nearly nil—the association between particular oils (e.g., farnesene, linalool, humulene. Gerianol, citral, limonene, etc) and definable and discrete flavors (e.g., floral, piney, citrusy, spicy, herbal, etc). remains naggingly unclear.

“There’s a glaring gap in our knowledge on how hop oils and their constituents interact to influence the taste and flavor of beer,” said Shaun. “There’s not a blue print or road map that tells us which oils to amp up or tamp down, or how do either of these compounds might be genetically associated.” The acids, on the other hand, are relatively simple, he said. “Just look at CZT [Columbus, Zeus, Tomahawk]. In a few decades the high water mark for alpha acids went from around 11% to around 18 to t 19%.”

In contrast, Hhop oils, Shaun muses, are a more “complex beast.” Hornbook biology teaches us that the traits of a particular plant are influenced by genetics and environment. The exact contribution, however, is not well known. We know that soil, climate, pests insect invasion, and temperature are a huge influence, he says, but there’s a “gap in our knowledge” when it comes to connecting specific DNA sequences to specific oils that wind up in beers that register in our brains as having particular qualities.

Do You Start with A List of “Super Aroma” Target Traits?

Again, the answer is no, at least for Shaun. We know from the literature that aroma hops are associated with certain traits. For example, aroma hops are generally defined as having:

* Low alpha acid content (less than 5%)
* Low myrcene oil (less than 50% of total oil)
* Low cohumulone alpha acid
* Alpha acid to beta acid ratio near 1.0
* Poor storageability
* Medium total oils content (.5 to 1.5 % of the whole hop)
* High humulene to caryophyllene ratio (above 3)

These are decent guidelines, but under OSU’s new aroma flagship program, defining worthy traits is the domain of Tom, while Shaun will attempt to breed for those selected traits.

To help identify the hops which may express desirable characteristics, Tom will be orchestrating hop sensory panels over the next few years. The panels will consist of experienced craft brewers, who will be asked to identify and describe flavor and aroma qualities of various hop brews. The data analysis from the sensory panels will be fed to Shaun, who will in turn cross targeted female and male hops for breeding, using conventional breeding techniques.

How does the Breeding Work?

Using Tom’s data, Shaun should readily identify the female plants. Choosing the male crossing partner, however, will be more difficult. Why? It boils down to who’s got the most accessible humulus lupulin. Females are teeming with it, but males – not so much. Their resin glands are much, much smaller, making it harder to harvest resin for analysis.

“We aren’t exactly shooting in the dark,” assured Shaun. “We have several decades worth of data on breeding stock. Since males don’t produce cones, it will be harder to identify the best males with an optimal oil profile, but it can be done. Basically, if the oil profile from the progeny of a particular male is desirable, we can trace the genetic contribution back to the male partner. It just takes lots of sampling and testing.” And the patience of Job.

Once seedlings are available, they are tested for Downey and Powdery Mildew and viruses. Weirdly-shaped, runty or puny “off-types” are culled out - the bad phenotypes. The vigorous chosen few are then transplanted to the field, where over a 3 to 4 year period they’ll be evaluated by the usual criteria (yield, disease resistance, appearance, size, etc).

Can New Technology Speed Up the Selection Process?

As we’ve learned from the People’s Hopmesiter, Dr. Al, the process of breeding, selecting, planting, harvesting, testing and releasing new hop cultivars can take up to a decade. Is there a short cut?

The short answer, again from Shaun, is “yes” for mega crops like corn, soybeans and wheat, but a strong “maybe” for hops. The idea is to associate genetic markers with desirable traits (e.g., citrusy aroma). Once DNA sequences are mapped and understood, scientists could simply study the sample leaf tissue of seedlings for genetic markers (without destroying the plant). They wouldn’t have to wait for the 1 to -2 years it takes for females to yield plump cones before they could run their battery of tests.

The technique, known as “Marker-Assisted Selection,” would allow breeders to plant hundreds and hundreds of female seeds, grow them into small plants, and pluck the leafs for DNA analysis. Using reliable molecular markers from seedlings to identify “home runs” would shorten the breeding program by many years, save tons of money and speed up the process of inventing new “designer” aroma hops.

Of course, all of this is years away. But the journey has begun, thanks to the work of Shaun’s colleague, Dr. John Henning, who has been working on genetic markers, mainly for yield and disease reistanceresistance, at the USDA-ARS Hop Lab in Corvallis, Oregon for the better part of the last decade.

Of course, we’ll still need to somehow associate particular DNA sequences with particular flavors and aromas, a herculean task further complicated by the changes a hop undergoes during its life and brewing cycle, depending on the terroir and brewer.

Variation is the Spice of Life

Dr. Townsend is like a kid in the candy store. “I’m very excited about the program, “ he said. “There’s so much to love about beer and hops, but there’s so much we don’t know.” Shaun is optimistic that with the data from Tom’s hop sensory panels, he can ramp up the process of selecting female and male partners for crossing, the results of which can be tested later on down the road..

Indie Hops shares Shaun’s enthusiasm. Hop science is on the cusp of harnessing the power of new technologies that have the potential for transforming how we go about breeding new hop cultivars. Consumers of craft beer want variety. They want to experience new aromas and flavors, from the big and bold to the faint and subtle. Unlike the industrials, whose mantra is “consistency,” crafties are shooting for the “new and different.”

The OSU breeding program is as big and bold as the richest pale ale. Instead of delivering one thing – more alpha acid – OSU’s finest aim to unlock the hop oils treasure chest. Tucked away in each pouch of mysterious humulus lupulin, there are as many potential flavors and aromas as there are human moods, temperaments, and personalities. This is the start of a brilliant new beer world in which brewers will be free to cook up a diverse roster of beers showcasing endless combinations of new and dazzling aromas and flavors, limited only by the imagination.

Roger Worthington

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