Making the Grade: Inspectors scrambling to make sure Yakima Valley hops measure up

YAKIMA, Wash. -- While beer fans flocked to Yakima to celebrate Fresh Hop Week, state inspectors have quietly been working overtime to grade all the hops harvested in the region.

Brewers want high quality hop cones — the sticky female flowers full of flavorful and bitter compounds — and they don’t want to see seeds, leaves, or stems mixed in. So a state Department of Agriculture inspection team takes samples from every sale lot of hops to assess the purity.

Thousands of samples — each extracted by punching a soup can-sized hole into a bale of hay — are processed by the lab every day in September and early October.

“We’re seeing every hop grown in Washington coming through here,” said inspection program manager Chris Wiseman.

They also inspect some of the hops grown in Idaho and Oregon that are trucked into Yakima for sale, she added.

Given that Northwest growers are expected to harvest a record 91.8 million pounds of hops this year, that’s a lot of work. Inspectors collect samples from 10 percent of the 200-pound bales in every lot of hops and bring those “cores” back to the WSDA lab in downtown Yakima.

The lab also looks for pesticide residue on food and analyzes animal feed and fertilizer samples, but every fall, hop grading takes over and the department hires dozens of temporary workers to collect and check samples of the fragrant flowers.

The samples for each lot are mixed together and workers pull out any foreign material, like a piece of rope, before measuring small portions that will be analyzed for the presence of leaves and seeds, which brewers don’t want to buy mixed in with their flower cones.

To separate out the tiny seeds, Wiseman puts a sample of the hops in an oven to dry. Then she grinds the dry hops through a sieve, which the turns cones into dust and leaves just the firm seeds and cones’ central spines.  Then, she counts seeds by hand.

“Hops are sticky, so we dry it out so it’s easier for the seeds to fall out,” Wiseman said. “For a really good grade, you don’t want to see a seed in here.”

Brewers prefer seedless female cones, but seeds indicate that male hop plants are also present in the fields to fertilize the female flowers.

After Wiseman pulls about a dozen seeds from a roasted, ground sample, she weights them. Trace amounts, less than 1 percent of the hops by weight, are rounded down to zero, the ideal score, she said.

All the samples moving through the lab carry barcodes, and when Wiseman scans the code and weighs the seed sample, the results are emailed directly to the grower.

Another fresh sample is checked for leaves and stems. The leaf bits and hop cones are green, but with a careful eye and tweezers, Wiseman pulls out a few darker green pieces. They’ll also be weighed.

Unlike apples or cherries, which have categorical grades, the inspection report on the hops just provides percentages. Zero percent seeds and 1 percent leaves and stems, for example, would be pretty good and will bring a better price than bales with higher percentages.

An extra sample is kept in the lab’s giant cooler for 15 days in case the grower wants to challenge the test results, Wiseman said.

The program is funded by a $1.25 inspection fee assessed on every bale of hops. Some growers opt to have the WSDA program assess the bitterness value of their hops as well.

Bitterness value, or B.V. in the industry, is a measurement of the alpha acids that give hops their characteristic bitter flavors, said Mike Firman, the manager of the WSDA lab in Yakima.

To test those acid levels, technicians grind the hop cones into a fine powder and mix them with a solvent that extracts the bitter compounds. Results range from 5 percent B.V. for aroma variety hops that are used more for flavor than bitterness to about 20 percent B.V. for alpha variety hops.

Most hop dealers do their own lab testing as well, but Firman said growers benefit from having the option to have the state lab do the tests.

“Basically, we’re the neutral referee, and growers want that because contract price is strongly influenced by B.V.,” Firman said.  

Most of this season’s harvest has already moved through the lab, Wiseman said, but she expects they have about another busy week left before all the region’s hops are out of the fields and into the warehouses waiting for brewers.

• Kate Prengaman can be reached at 509-577-7674 or at kprengaman@yakimaherald.com. Follow her on twitter @kprengaman.