More Aroma Oil, Faster: The Dry Hopster’s Holy Grail

OSU tests IH pellets vs Cones for aroma intensity and oil extraction rates

OK. OK. You want more aroma. Do you dry hop with whole cone hops, or pellets? And how long? You’ve got limited capacity. Do you dry hop for a week, or something less than that?

Questions. For answers, where do you turn? A textbook? A magazine? Your buddy? The BA message forum? Google? Or do you just wing it?

We tried all of the above, but decided the questions were serious enough to warrant serious study utilizing the scientific method and the best available technology.

In short, we called Peter Wolfe and Dr. Tom Shellhammer at Oregon State University. They spent a year researching the questions. It’s pretty interesting, even for a liberal arts guy like me. In fact, it’s fairly startling.

We won’t post the study here, as it has not yet been published. But, for details, give us a call, and we’ll give you a closer look at the data. For now, here’s a summary.

* A 10 member sensory panel evaluated the intensity of dry hop aroma from Cascade pellets and whole cones and concluded that the pellets provided more intense aroma.

* Beer samples dry hopped for one day had significantly more aroma than beer dry hopped for 7 days.

* Irrespective of form (pellet or whole cone), the concentrations of hydrocarbon terpenes (eg, myrcene, humulene and limonene) peaked between 3 and 6 hours in dry hopped beer and then declined, while the concentrations of terpene alcohols (e.g, linalool and geraniol) continued to increase throughout the 24 hour dry hop extraction.

A few caveats.

First, not all pellets are the same. The pellets used for this study were supplied by us, Indie Hops, and we’ve previously shown that our pellets are different in terms of the average particle size, the diameter and the “bakedness” (our grist is extruded at between 106F and 115F).

We’re gratified to learn that our pellets produced about twice the intensity of aroma than whole cones. That’s huge! The conclusion reinforces what common sense told us: nature designed the hop flower to keep the oils “in”, not let them out, while IH pellets were designed by guys who wanted to get the oil “out.” We deliberately designed our mill to chop up the cone in bigger, coarser particles so that we could open up without pulverizing the oil-exuding lupulin glands.

Second, the rapid extraction rates were likely influenced by the temperature of the solution (23.3C, which may not be representative of real world conditions), and the hops were continually stirred. Although there’s been ongoing anecdotes and discussion about methods for agitating or recirculating/re-entraining hop grist in the tanks, we don’t have a reasonably available tried and true technology for re-suspending hops during dry hopping.

The research suggests, however, that the machinery needed wouldn't be too terribly difficult, and it only need to engage for a few days.

Third, the sensory panel consisted of 10 trained beer geeks who measured the aroma intensity on a scale of 0-15 based on the smell, not taste. To quantify the aroma compounds extracted (e.g., linalool, myrcene, etc), as well as the extraction rates, OSU used all the usual hi-tech stuff.

The take home: if you don’t have a torpedo, prefer (IH) pellets over cones, don’t have limited tank capacity and like big oily aromas, you’re not measurably losing anything, other than lore points, by not using whole cones.

And if you really love big oil, keep noodling and tinkering with new ways to keep those pellets circulating. And if you really love big oil but aren’t big, if you can keep those pellet particles suspended, you might also be able to save money by shaving 3-4 days from the standard dry hop schedule.

In the meantime, we’ll keep asking the questions.

RGW
2/29/12

The name of the unpublished manuscript is: “Dry Hop Aroma Extraction and Sensory Evaluation Report on Phase II dry hopping experiments,” by Peter Wolfe and Thomas H. Shellhamer, Ph.D, Dept. of Food Science and Technology, OSU, Corvallis, Or. (1/2012).

Note: Check out these Guth Portable Agitators used for mixing, stirring and homogenization of liquids such as wine. Could the same technology be modified for use in agitating hops during dry hopping?

Hop Harvest Time: When and How Do You Know? OSU’s Tom Shellhammer Has A Clue

When is the optimum time to harvest hops for aroma?

How will you know when that optimum has been reached?

Do different aroma oils reach their maximum concentration at different times as the cone ripens?

These are some of the questions that drive Indie Hops to fund hop ‘maturity’ studies at Oregon State University. We are pleased to announce that the results of our first effort to wrestle with this topic will be presented at this year’s Craft Brewers’ Conference in San Francisco by OSU Professor Dr. Tom Shellhammer on Saturday, March 26th.

In late summer and early fall of 2010, Cascade and Willamette hops were collected on three successive weeks at three Oregon locations and analyzed for aromatic compounds by Gas Chromatography and Mass Spectrometry. Thirty-one different GC ‘peaks’ were identified and compared.

In a fortunate coincidence, single hop beers using some of the very same hops were brewed by Deschutes Brewing and later judged by a sensory panel at OSU. This allowed us to relate some of the lab analysis to actual flavor perception in beer, something that will be pursued more fully in subsequent projects.

The complexity of hop aroma is so great that it’s not surprising to find that each attempt to answer one question brings several more to the surface. And although this first study is too limited to produce any grand conclusions, some commonly heard notions about hops now seem to be less certain. If you’re going to CBC, consider attending Dr. Shellhammer’s presentation to judge for yourself.

Perhaps some day we’ll learn that a 5-day difference at harvest can mean the difference between a decent well-hopped craft beer and a remarkable one.

See you at the CBC.

3/21/11

Flower to the People: OSU Empowers Hop Sensory Panel

Hood River, Or. Oregon State's Hop Docs wanted feedback from Pacific Northwest brewers on building a new aroma hop and it sounds like they got an earful.

The consensus? Dial down the alpha, jack up the oils, and add something "tropical" to our flavor arsenal beyond the all-pervasive citrus bomb.

In it's mission to breed new aroma hops, Oregon State pulled together a panel of seasoned craft brewers, predominantly from Oregon, to evaluate a series of single hop brews. The format was simple:

• Create a sensory neutral environment .


• Present an experienced panel with six (6) single hop brews, plus a series of dry hopped brews.


• Ask each to fill out a confidential form that best describes the primary hop aroma (viz., floral, fruity, tropical, spicy) and flavor (viz., cirtrus, herbal, grassy, woody, sulfury, cheesy). For each rubric, the panel was asked to further define secondary descriptors, for example, my personal favorites: rose, apricot, mango, anise, sagebrush and not-so-favorites like sweaty, garlicky, leathery and rabbit urine-ish.


• And, finally, after each pair of test brews, open up the panel to a robust but sincere discussion.

The hop sensory panel is the first step in a novel two-part strategy designed by OSU professors Tom Shellhammer (the fermenter/hop chemist) and Shaun Townsend (the geneticist/breeder) in their science-driven quest to breed new aroma hops. Tom and Shaun have been collaborating since January 2010 in their noble mission, pursuant to a $1 million grant from Indie Hops.

The panel was convened in conjunction with the annual meeting of the Pacific Division of the Master Brewers Association (MBAA).

Help Us, Help You

The sensory panels using trained brewers, explained Dr. Shellhammer, is critical in providing clear guidance to Dr. Townsend, who will be selecting hop candidates for crosses in the hope of amplifying known or new desirable characteristics.

"We're looking for consensus," said an optimistic Dr. Townsend, whose mind seemed to be spinning with ideas after the panel. "Early in the breeding process, breeders generally work with little feedback from brewers and chemists. This is an important first step in selecting genotypes that can lead to new cultivars that express the profile sought by brewers. Having the end-product users involved at the front end of the breeding process eliminates a lot of the guesswork and gives me a clear set of goals."

Dr. Shellhammer was equally pleased. "The brewers were excited about being asked to participate in the process. Their candid and honest evaluations will help us narrow down the target characteristics. In the end, we're looking to develop alternatives to the current menu of commercially available hops that will endure the test of time."

The next step is for Dr. Shellhammer to analyze the data for patterns. Over the next few years, Dr. Shellhammer will be conducting at least six sensory panels. He is in early discussions with the San Diego Brewers Guild to hold a second hop sensory panel in early November of 2010.

More Tongues and Noses, More Data, Better Science

Several of the brewer panelists agreed that the research effort was both valuable and long overdue. One brewer told me that it was "just nice to be included. Instead of a few brewers pursuing their own agenda behind a veil of secrecy, it was great for OSU to open up the discussion among a diverse group of brewers. In the end, everyone benefits from innovation." To preserve the objectivity of the effort, and to avoid any hasty conclusions, OSU is keeping confidential the identity of the hop cultivars that were evaluated by the panel.

Another area of research of keen interest to the brewers was the optimal harvest date of aroma hops. As part of the Indie Hops grant, OSU will be conducting a pilot study on the correlation between harvest date and oil content in fresh cones. The brewers did not venture to say which specific oils they were interested in seeing more of. For now, their uncomplicated message is less alpha, more total oils. The panel also raised the concern that the craving for super alphas has led to a proliferation of harshly bitter concoctions that tend to blow up the tongue like a wet sponge.

The road to new and useful cultivars is long, narrow and mostly uphill into a headwind. There are no shortcuts -- no magical bullets -- although advances in molecular marker mapping could one day speed up the process of selecting desirable traits (such as disease resistance, crop yield, and, since we're dreaming here, guava-mango aroma). As Dr. Townsend explains, "There's a reason that Fuggles, Saaz, East Kent Golding, and similar ancestral varieties selected before 1900 are still used today: hop aroma and flavor is an exceedingly complex beast and very difficult to select for."

Planting the Seeds of Future Innovation

Every paradigm shift, every great revolution, has to start somewhere. The prize starts with a vision. The sensory panels will help bring the prize into focus. Amping up oils (after first determining which of the 200 plus hop oils are useful) presents challenges that are orders of magnitude greater than the shade tree mechanic task of boosting the alpha juice.

Put simply, when it comes to tinkering with aroma oils, the current state of the art is somewhere between 1st and 2nd grade. Using conventional breeding methods, we can of course get to the “promised land” in my lifetime – and we will much sooner than that. But to get there repeatedly, in addition to bucket loads of data, ample amounts of sweat and tears and gobs of good luck, to paraphrase Mr. Spicoli from Fast Times : we're going to need to develop a cool set of new tools, pronto.

Indie Hops is naturally proud to sponsor OSU’s aroma hop breeding program and it was especially gratifying to see over a dozen OSU undergraduate “eager Beavers” helping out with the research effort. I also want to thank them for leaving me a six pack of their test brews – sniff, sniff, sip, sip... hmm... spicy with a whisper of anise and a minty fresh finish…

Roger Worthington
5/17/10

OSU's Quest for Aroma

Check out OSU's beermeister, Dr. Tom Shellhammer, and hopmeister, Dr. Shaun Townsend, on television! http://www.kval.com/news/local/89487982.html?tab=video The two titans of the Oregon academic beer scene discuss their quest to "add new scents to Oregon suds" (quote courtesy of KVAL's Todd Milbourn, and a good one!). Indie Hops is pleased to provide the seed money for this noble quest.

Tom and Shaun are the perfect spokesmen for the new age of creative breeding and brewing. Goodness these two are lean, fit and poised! They exude the tranquility and clarity of an athlete who's just run 5 miles, or biked 50, cooling down with a refreshing, herbal and tose-tingling craft beer.

By the way, we appreciate the vote of confidence from the TV anchorman, but Indie Hops is brand new to the scene -- we can't yet lay claim to being the biggest hop merchant in Oregon! But our eyes are on the prize.

And finally, a buddy of mine watched this, called me and demanded an explanation. "Do you mean to tell me you donated all that money to invent buttered popcorn flavored beer?!" Breathe easy, buttered popcorn scented hops is not tops on the agenda. And yet, I wonder, could it be done? Try them, try them, then you'll see...

Roger Worthington
3/31/10

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
3/15/10