Optimal Oil Extraction 101.

Whole Cones vs Turkish Espresso Pellets: Where’s That Sweet Spot?

How does a brewer get the most hop oil for the buck? Does he dry hop with whole cones? Or with pellets? The research shows that a brewer using pellets can extract about 30-35% more alpha acid in solution than he can from whole cones, but I’m not aware of any oil extraction studies pitting cones vs pellets.

It’s not a perfect analogy, but assuming the same holds true with respect to oil extraction – that a pellet offers up more oil for extraction than a cone, what is the optimal design of the pellet?

In short, where’s the sweet spot? On one end, we have a properly harvested, dried, baled and stored whole cone flower. On the other, we have that same flower pulverized into a fine Turkish espresso powder compressed to a 3 mm pellet.

How do we open up the flower to best utilize the oil inside the resin glands without unduly exposing them to the ravages of oxygen and heat? And why do we need to “open” them up at all?

The answer to that last question is intuitive. Look at a whole cone. The oil together with the resins is inside the tiny cup- shaped yellowish resin glands. The glands themselves are coated with a permeable membrane, or skin. Even though it seems logical, there’s no definitive research proving that heat or air have an impact on the gland’s permeability. The permeability varies between hop varieties.

The inside of the gland consists of many molecules, including the hop resins, the oil (about 250 bio-chemically distinct compounds) and anti-oxidants (like quercetin and xanthohumol), which themselves help prevent oxidation and prolong the shelf life of both the oil and the resin.

Nature designed the cone to protect those precious glands from predators. They’re tucked around the vertebrae of the cone (the strig) where they cling to the bracteoles, the internal scales shielded by the weather-exposed bracts. If you poured water over the cone, it’s not likely that much would penetrate the bracteoles and reach the resin glands (like water off a duck’s back).

If you dipped the cone into an aqueous solution, more water would reach the central axis, but the process of extracting the oils from the glands is not very efficient. This became clear to me when I recently scooped up a handful of spent whole cones that had been dry hopped. I opened a few up and I could plainly see a few yellowish glands, all perky and plump.

It’s not a great analogy, but think about coffee beans. You can’t dip coffee beans into hot water and efficiently extract any appreciable amount of oil. To bring out the oil, you need to grind the bean up. The question is, to get the best flavor and aroma out of that bean, how do you preserve the bean, when do you grind it up, and how finely do you grind it?

I’ve been applying these same questions to the hop cone. It’s clear to me after examining several pellets from different pellet mills that the size of the pellet and the coarseness/fineness of the grind dramatically influence both the quality and quantity of utilizable oil. Granted, I haven’t measured the “extraction” rate or amount in a laboratory. But it’s fairly well known that hop oils degrade rapidly when they’re exposed to heat, light and air.

If the key to optimal oil extraction is maximal lupulin gland preservation, but the oil glands are tucked inside, how does one “process” the cone, or open it up, and shake out the glands, without unduly rupturing, cooking, or shattering them? I called the People’ Hopmeister , Dr. Al Haunold, for help.

It turns out there is a middle ground, but I’ m not sure how sweet it is. Dr. Al tells me that there was a technique developed years ago for shaking the lupulin glands out of the cone and capturing them fairly whole: pure, concentrated glands containing resins and oils. The shake-out process requires freezing the dried cones followed by a “gentle” shaking. The cones are not compressed into a bale. The process is laborious and both time and space consuming.

The shake-down-and-out method might work in a Willy Wonka-ish factory run by oompa loompahs who never complain. But, after investing a few million in a pellet mill, not sure I’m ready to throw down for a massive shake down operation. Nor do I think there’s an immediate demand for pure unfractionated hop oil, as brewers are accustomed to using pellets and cones, and few have drilled down to knowing precisely which of the several dozen popular oil “essences” they want for each brew style.

Al explains that the resin glands during picking and drying tend to fall out of the tossed-about cone. The rate at which the glands fall or shake out depends on the variety, the moisture content, and the harvest date – if the cone is harvested late and is therefore too “fluffy,” then the glands are more likely to fall out – a phenomenon he calls “shattering.”

A badly harvested, picked and dried cone can lose up to 40% of its lupulin glands. Where do they go? They fall on the floor. Per Al, you can separate the good farmers from the mediocre or worse by the concentration of yellow lupulin glands on the picking and drying floors – the so-called “Yellow Floor” syndrome. And by the way, according to the Hop Oracle, it’s not unusual for the farmer to scoop up all that yellow gold and sell it separately to extractors in years of hop shortages. In good hop production years, there may not be much of a demand for such sweepings.

All that piney, citrusy, mango-ish, floral oil, together with all the bittersweet alpha, swept away like dust in the wind. A tragedy!

So, where do we go from here? We continue to question and tinker. I recently met with a brewer who said he wanted to experiment with dry hopping using both pellets and whole cones. He’s convinced that while traditional, and perhaps even romantic, dry hopping with whole cones leaves a lot of juice on the table (in addition to soaking up a lot of valuable beer). He wants to dry hopping using cones, in one batch, hand, and coarsely ground and fatter IH pellets, in another, and evaluate the differences.

Straight up he says whats driving his curiosity is a blend of both wanting to up the quality of his brew and save money by using fewer hops but extracting more flavorful oil. We like that. Question everything.

In the meantime, we control the things we can. For example, we will freeze our freshly harvested 2010 bales on receipt. We’ll hammer the flowers minimally and squeeze them through our die lovingly at under 110 Degrees F. And we’ll double nitrogen flush our cool pellets, wrap them in an impermeable layer of foil, and whisk them right back into the deep freeze in under 70 minutes. Can’t wait to crank it up!

Roger Worthington
7/27/10

Part III: Dr. Al Haunold Hop History

Alpha Obsession: Origins of the Race for More Bittering “Juice”

Today it’s well known that alpha, or “juice,” is a form of hop currency. In an industry run more and more by bean counters who are eager to sacrifice a bit of quality to make a few more pennies, when it comes to choosing hops, the juice content of a hop is more often than not the deciding factor. Put simply, the more a processor can extract from a single cone , the fewer cones he has to buy.

Where did this obsession with alpha acids begin? To answer that, I spoke to Dr. Haunold, who it turns out was on the front lines in the race for more alpha. The race began in the early 1960s with a challenge that resulted in a hunch that yielded a breakthrough that the growers hated so much they threatened to suppress it with legal action. Oh my! Read on.

Early 1960s: Pride of Ringwood Rules

In the early 1960’s, when it came to high alpha acid, a hop from Australia called “Pride of Ringwood”(PoR) ruled. It sported a hefty 11% juice content, the high-water mark for commercially available bittering hops worldwide. PoR, however, did not thrive in the US. Instead, we (especially in Oregon) relied on the UK-born Bullion and Brewer’s Gold, which weighed in around 10% alpha. One problem with the UK B&B is they didn’t store well, losing as much as 50% of their juice in 4-5 months of unrefrigerated storage.

In the mid 1960’s, hop processors began to experiment with extracting the acids from hops. They saw the future, and the future was bitter syrup served up in air tight steel canisters. A Canadian chemist, Dr. Lloyd Rigby, had years earlier discovered that alpha acid resin actually had three major components: humulone, cohumulone and adhumulone, which made up about 10 or 11 of the total weight of a dried hop cone (e.g, the B&B sisters).

Dr. Rigby seized on the juice craze. He forecasted that each percent of additional juice was worth millions, so it was well worth trying to engineer new hops with a higher alpha content. John I. Haas hired Dr. Rigby to develop a hop extraction plant in Yakima. Dr. Al Haunold met Dr. Rigby in the late 1960s, and the former challenged the “new kid on the block” to breed a new hop that pushed the alpha envelope.

“I accepted the challenge,” recalled Al, who had just joined the USDA as hop geneticist in 1965. At the time, the predominant all-purpose hop in the Pacific Northwest was Cluster, which stored well (refrigeration was uncommon in those days), carried a low price, and depending on the year and the test often rang the juice bell at close to 8 %, but was reputed to have an undesirable “black currant” aroma. The growers generally were content with Cluster.

At the time, the hop cognoscenti ordained that no hop could exceed 11-12%. They also prophesied that no high alpha could be stored more than a few months since juiced up hops were branded as “poor keepers.” Juiced up hops were also expected to have high co-humulone content (above 35 %).

Gold Fever

Undaunted, Dr. Haunold, driven by the new orthodoxy that each 1% percent alpha was a “gold mine,” began tinkering appropriately enough with hops related to Brewers Gold (BG). He started with a female BG-derived seedling that he crossed with a male (which had a sprig of BG and a sprinkle of German aroma hops in its genetic blood). “You never know for certain in science what will work, but I had a hunch that we’d strike gold with this parentage,” said Dr. Haunold.

He started in the early 1970s with 400 seedlings of the above mentioned cross and by 1976 had narrowed the lot down to 36 thriving seedlings selections. Dr. Haunold began growing the “super alpha” selections in a few replicated plots near Corvallis. Most selections showed promise for mildew resistance and above average alpha. The cones were compact, easy to pick, clean, and they dried and stored well – in a word, they were “gorgeous.”

Al knew he had the tiger by the tail when his chemist tested a few cones, read the results and suspected that somebody had “doctored the numbers,” as the alpha acid content weighed in at a scorching 13-14.5%! About 50% more juice per cone! A new world record!

Noting the parentage and the shape of the big bold cone, Al decided to name his brainchild “Nugget.” Now emboldened, our young over-achiever was ready to start growing Nugget in test plots in Idaho, California and Washington.

But a funny thing happened on the way to more juice. The Washington hop farmers grabbed their pitchforks and torches and fought back, sort of like blacksmiths shouting down the new gas-powered Iron Horses. The Washington growers were satisfied with Cluster (up to 8% alpha). A survey at the time showed that of 10 “priorities” , developing higher alpha acid hops ranked 9th, just above the bottom.

Too Good to be True

One can understand the grower’s protest. In the quest for higher juice, brewers and hop processors, who by then had figured out how to hop flowers to alpha juice, both demanded super alpha varieties. The more juice they could suck out, the fewer cones they needed, which meant that fewer acres needed to be planted. They of course did not pay extra for each percent of alpha, since they bought the cones by the pound. The Washington growers retaliated by closing their the borders to the Cluster-bustin’ Nugget, even for testing.

However, Dr. Rigby – recall, he’s the hop chemist who John I Haas hired as their Master Extractor – said “wait a minute, Nugget sounds like the Holy Grail, I want some!” So he arranged to have a few acres of the lupulinona non grata Nugget grown on J.I. Hass’ property. To be sure, our budding hopmeister certainly wasn’t a troublemaker – far from it. He was surprised by the protest. At the time, USDA hop scientists like Al under a “tristate agreement,” which included Washington, Oregon and Idaho, had a perfect right if not duty to test and evaluate hop selections in these key hop states. To prevent any one state from gaining an undue growing advantage, all 36 of the most promising selections were provided to each state under strict guidelines.

Nonetheless, the Washington Hop Commission and some of its grower members were outraged. They threatened legal action. That didn’t work. Then they threatened to order the local police to trample onto Haas’ private property and physically uproot the blacklisted Nugget rhizomes.

Dr. Rigby responded to the threats by promptly erecting a 10 foot high Cyclone fence around his precious crop and installing motion sensors and flood lights – everything short of pit bulls, claymore mines and armed Pinkerton agents. Over my dead hop! Across this line, you will not cross!

The Patience of a Public Servant

In the end, the bluff was called and Dr. Rigby nursed his Nuggets. However, because of political pressure, Dr. Haunold did not release Nugget to the public until late 1981 , even though it had been ready to roll since about 1978. Why? “I was a public servant,” said Dr. Haunold modestly. “Since a very loud fraction of public clearly did not want the fruits of my labor, I just waited until the time was right.”

But wouldn’t Nugget serve the public? I mean, this was your major opus, your brainchild, your baby? Didn’t you want to unleash your masterpiece? “No,” he replied with typical matter-of-factness. “The Hop Research Council and the Hop Commissions of several states asked me to delay release for a few years because the growers felt threatened. End of story.”

During those three years between 1978 and 1981, while Al was waiting, his
coworker in Idaho (Dr. Bob Romanko), was putting the finishing touches on his own Super Alpha pet hop. Dr. Romanko had been experimenting with a new cultivar that came to be known as “Galena.”

Suddenly, in 1980, a world-wide hop shortage struck, and the need for US grown bittering hops just ratcheted upward, as the price for alpha extract instantly quadrupled. Unlike Al, who answered to all three states, Romanko answered only Idaho’s hop commission, which basically said “bring it on!” In early 1981, the Idaho Agricultural Experiment Station at Parma released Galena to the public. Galena’s juice came in just under Nugget’s, at 12% by weight.

1980 Hop Shortage: Brewers Scramble as Alpha Spikes

The world-wide shortage of alpha acids following the 1980 harvest had brewers scrambling to obtain additional alpha, at any price. This affected especially those brewers who had not entered into forward contracts and thus had to pay as much as 11 dollars for a single pound of hops, an unheard of price at the time. Farmers did not get rich since they had long-term contracts and had to deliver at the lower contracted prices. The few farmers who had excess production (above the contracted prices) could, however, sell their non-contracted “spot hops” to the highest bidder. And bid high the brewers most certainly did.

Hop dealers now offered ever increasing prices for forward contracts of high-alpha hops, with premiums of up to 25 cents for each quarter percent alpha above 9%. Growers could make more in premiums than they could get just for a pound of hops with Galena and Nugget. Dr. Haunold responded by launching a massive Nugget propagation program and established multi-acre test plots in Oregon, Washington and Idaho, this time, without having to duck pitchforks or rotten tomatoes.

Galena rootstock was freely available at that time and Washington growers stampeded to get their hands on available root stock despite a quarantine of importing non-inspected rootstock into the state. Alpha was suddenly all the rage and its emergent value changed the way hops were priced.

Al recalls that one Oregon grower told him that he had forward contracted at the alpha premiums for 4 years starting in 1982. By early 1984, however, high alpha hops had flooded the market and the price began to slide. The dealer went back to the grower and offered to buy back their high priced contracts for 50 cents on the dollar, provided the grower would pull out his alpha plots that were contracted out for a few more years.

According to Al, the grower accommodated, even though it meant he’d be eating major labor costs. The grower had just finished stringing on the Friday before the deal was cut on a Monday; on that same day the grower ordered his foreman to go back and take the strings down as they were no longer going to be growing what they had contracted for.

What have I wrought?

Dr. Haunold looks back on those days with a mixture of pride, surprise, and perhaps even a tinge of regret. “I guess I opened the flood gates. The race for higher alpha acid hasn’t abated. We were told back in the early 1980’s after my Nugget that ‘no way’ can you breed a hop with more than 14 or perhaps 15% alpha. Now, there’s new hops juiced to the gills at over 18%, both in the US as well as in some other hop growing areas around the world. ”

“I didn’t want to make a fuss about not being able to release Nugget earlier. The farmers, it turns out, were absolutely right to be worried. The big brewers today can get the same amounts of alpha at very reasonable prices from one-third less acreage. Farmers back then and still for the most part today get paid by the bale, not alpha points. I can see why they’d resist, especially today when it seems like the alpha craze is retarding the growth and variety of aroma hops.”

Roger Worthington
1/26/2010