SubZero Hop Kief: A New Liquid Dry Hop Extending Day One Freshness for Months

Published: April 29, 2024
A contain of SubZero Hop Kief shot outside

While innovations with hop products improve flavor and aroma, the name of the game is yield. Flowable hop innovations—we’ve covered a lot of them, including HopHaze, Incognito, SPECTRUM, FLEX®, Salvo™, and DynaBoost (formerly YCH 702)—are made for use in hot- and cold-side additions to save money and yield, while giving you true-to-varietal hop flavor and aroma. Most recently, Freestyle Hops added its cold-side flowable hop product to the market: SubZero Hop Kief.

SubZero Hop Kief provides another option for brewers to get optimal flavor and aroma from some of the best Southern Hemisphere hops on the market. We chatted with Freestyle Hops Managing Director David Dunbar and early adopters of the product at Fast Friends Beer Company to learn more about the product, how it differs from other flowable innovations, its benefits, and more.

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What Exactly Is SubZero Hop Kief?

A side-by-side photo showing different Hop Kief flavors

Photography courtesy of Freestyle Hops

According to the Freestyle Hops website, SubZero Hop Kief is a liquid dry hop intended for use in post-fermentation as part of cold-side hop additions.

“When we developed it, we wanted to create something true to lot for dry-hop character as best as possible,” Dunbar says. “And be flexible on usage on the cold side.”

Made with a cryogenic, solventless separation process, SubZero Hop Kief is all natural and comes entirely from New Zealand-grown hops. You can also add the product to a brite tank before carbonation for an additional hop boost of both flavor and aroma.

“We wanted to make sure what we created would work across other products like N/A beer,” Dunbar says. “We wanted to check boxes for food safety and wanted something directly edible so it can be added even just prior to packaging for N/A products and beer.”

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Freestyle Hops Explains the R&D Process Behind SubZero Hop Kief

A photo looking inside a SubZero Hop Kief container

Photography courtesy of Freestyle Hops

When we developed it, we wanted to create something true to lot for dry-hop character as best as possible,
David Dunbar - Freestyle Hops

So how did they get there?

Many trials.

Dunbar says Freestyle began its process about four years ago when it surveyed similar alternatives and was unsatisfied with the number of characters that would volatize.

“We didn’t want to lose that,” Dunbar says.

About a year and a half ago, Dunbar says they got to a place where they were happy enough with SubZero Hop Kief to send it to a collective of breweries to experiment with it and provide feedback.

After six months of feedback and some minor tweaks, Freestyle Hops finalized the product available today.

“About twelve months ago, with minor tweaks, we were comfortable with what we had,” Dunbar says. “It’s close to that today.”

Fast Friends is part of Hāpi Research, a collaborative industry-led hop breeding and market development program aiming to improve craft beer and hop farming in New Zealand. Freestyle approached them about SubZero Hop Kief during the R&D process.

“We’re lucky to have a relationship with Freestyle,” Fast Friends Director of Brewing Ops Keith Shaw says. “We purchased our first hops from them in March last year, and they asked us to be a part of [the Hop Kief R&D]. We started using it, and we love it.”

Shaw points to a double IPA they trialed with Hop Kief, where they used Southern Cross Hop Kief.

“We were blown away by the aromatics, and the flavor was sharper,” Shaw says. “Then we threw it in our New Zealand hazy IPA. We’ve been using it in conjunction with T-90 pellets, not as a replacement.”

Fast Friends Head Brewer Luke Wortendyke says Freestyle makes up a considerable portion of the hops they use, so it was a no-brainer.

“Our core hazy IPA is all New Zealand hops and almost all Freestyle Hops,” Wortendyke says. “We focus on yield and profitability, so we saw an opportunity to replace some T-90 pellets with the Hop Kief. It provided a better yield and complex, clean hop character.”

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How Does SubZero Hop Kief Differ From Other Cold-Side Flowable Products?

Dunbar says that having no solvents is a critical difference in the SubZero Hop Kief.

“Most of those others are CO2 extracts, so they are made with solvents. It’s only going solubilize what is in liquid CO2,” he says. “That is one of the reasons we didn’t go down that path. For the varietals we grow, we wanted to make sure we’re preserving that hop character.”

Dunbar adds that the patent-pending separation process is a major difference between SubZero Hop Kief and the other flowables.

“Most of the complexity is driven by wanting to end up with something effective on the cold side,” Dunbar says. “Separating the stuff we don’t want to solubilize things is the biggest challenge.”

For the varietals we grow, we wanted to make sure we’re preserving that hop character.
David Dunbar - Freestyle Hops

Wortendyke found something he liked about SubZero Hop Kief right away.

“What drew me immediately was it is solventless,” Wortendyke says. “It is packaged with food grade, no solvent or CO2. You get a true characterization of the hop.”

Wortendyke says he has consumed many IPAs made with flowables, and it’s pretty obvious when that’s the case.

“They seem to be one-track aroma on them,” he says. “The solventless gives you a true representation of hops in terms of cold side.”

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What Are the Benefits of SubZero Hop Kief?

A promotional photo of MataMata, a craft beer from Fast Friends Brewing Company brewed with SubZero Hop Kief

Photography courtesy of Fast Friends Brewing Company

Wortendyke and Shaw feel like SubZero Hop Kief brings many benefits to the brewing process.

“Aroma is the number one benefit for me,” Shaw says. “Then yield.”

Though they haven’t conducted trials for the yield increase, Wortendyke estimates anywhere from a five to ten percent increase in yield, depending on the beer.

“[For] our core hazy IPA, Matamata, we use around twenty-five to thirty percent T-90 replacement and get a six to eight percent increase in yield,” Wortendyke says. “Which is huge. It’s almost as good a yield improvement as [with the] centrifuge.”

He adds, “And the consistency from the aroma. You are just mixing liquid with liquid, a known result every time.”

... you have a more potent flavor and aroma.
Keith Shaw - Fast Friends Beer Company

Shaw says that SubZero Hop Kief is also cost-efficient—on par with the price point of other similar products.

“But it’s giving such a higher yield and increases the shelf life of your beer,” he says. “And you have a more potent flavor and aroma.”

Shaw notes that an eleven-pound bag of Nelson and a vial of the Nelson SubZero Hop Kief are almost one-to-one in price.

Wortendyke echoes Shaw on the shelf life.

“We’ve added it to a serving tank three to four weeks after we racked it just to bring it back to Day One freshness,” Wortendyke says. “We’ve had Day One freshness for two months. I haven’t met a dry hop that achieves that.”

Dunbar points to two main benefits of SubZero Hop Kief.

“The two biggest ones in our minds are adjusting fresh hop flavor at the end—in the brite or just prior to packaging—and adjustments that will hang on really well in packaging,” he says. “And the other is being able to hit flavor and aroma profiles that would be really challenging to do with just T-90s.”

Dunbar adds, “Perhaps the beers are seeking an intensity, and this helps avoid green matter and other drawbacks.”

Beyond those two, Dunbar says SubZero Hop Kief really benefits smaller brewery operations.

“Smaller breweries can use this for the intensity without sucking up much of the yield,” Dunbar says.

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What Is the Dosage Rate of SubZero Hop Kief?

A hand holding a container of Motueka SubZero Hop Kief hop extract

Photography courtesy of Freestyle Hops

Freestyle Hops suggests that you dose SubZero Hop Kief at around 0.2ml per liter.

“One 275ml bottle has the flavor of a 5kg bag of T-90s,” Dunbar says. “If someone wants to add that much in T-90s, they’d add a 275ml bottle of Hop Kief.”

He adds, “We wouldn’t recommend someone do a heavily dry-hopped double IPA that they are trying to exceed forty percent of the hop load with Hop Kief.”

One 275ml bottle has the flavor of a 5kg bag of T-90s,
David Dunbar - Freestyle Hops

In that case, Dunbar says to use at least sixty percent T-90.

“[For] a Mexican lager, you could use the entire load of dry-hop with Hop Kief,” Dunbar says. “It’s very style dependent.”

Fast Friends doesn’t even approach that forty percent threshold.

“We haven’t messed with anything over thirty percent, but we will in the future,” Wortendyke says.

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Which Style of Beer Works Best with SubZero Hop Kief?

“IPA in general,” Wortendyke says. “[But], I think it shines the best in a West Coast IPA because that’s a clean beer in general.”

Dunbar sees it with lower-ABV hazies and pale ales, though he admits those are in higher demand in New Zealand and Australia.

“I think it’s just allowing people to hit levels of bright, fresh hop character that hangs on in packaging beers that [you] otherwise wouldn’t get,” Dunbar says.

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About The Author

Giovanni Albanese

Giovanni is a content writer for Next Glass, contributing to the Ollie blog. He is a writer by day and a brewer/business owner by night, owning and operating Settle Down Brewery & Taproom in Gilroy, California.

Giovanni is passionate about a number of things, including history, documentaries and sports, but none more than reporting/writing and brewing beer. After receiving a radio broadcasting degree then a journalism degree from Salem State College in his home state of Massachusetts, he relocated to California in 2008.

Then, his writing career kicked off – covering sports, business, politics and more along the way – while concurrently dabbling in home brewing. The home brewing turned pro in 2021 when he launched SDB Brewing Company. Settle Down Beer officially opened in February.

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