Trying to bring food-grade safety standards to the budding regulated cannabis industry wasn’t easy for Jill Ellsworth, founder and CEO of cannabis kill-step solution provider Willow Industries. As a registered dietician with a master’s degree in food science and nutrition and a resume that includes launching (and selling) a Santa Barbara- and Denver-based cold-press juice company and a Denver-area beverage distribution company, she looked at the nascent regulatory landscape through a food safety lens.

Colorado regulators required that cannabis cultivators test their products for microbials, including molds and yeast, with failing batches sentenced to destruction without an opportunity for remediation. “What I did not see in the regulations was a required kill-step,” Ellsworth told Cannabis Business Executive in an interview, referring to the precautionary step in food and beverage manufacturing used to kill potential pathogens. However, traditional kill-steps like pasteurizing or cooking can’t be used for most cannabis products.

“I had the idea to find a way to clean weed–to invent a kill-step and bring that to cannabis,” Ellsworth explained. The solution she and her team developed leveraged pure ozone in a contained system that kills microbes such as yeast, mold, aspergillus, E. coli, and salmonella. Dubbed WillowPure, the product launched in the cannabis market in 2016.

Despite the research backing the solution as viable, Ellsworth encountered a lot of skepticism about her system–after all, ozone was, and continues to be, used as an odor control technology for urban grows and greenhouse operations. There also was a not uncommon sense in the cannabis industry that if a grower’s product was contaminated, they should not be in the cannabis industry. “But that’s nearly impossible in commercial growing operations,” Ellsworth said.

Ellsworth was challenged in her first few years (“I cried all the time in the beginning,” she said), but a national scare around vitamin E acetate causing lung issues in vape consumers and California requiring aspergillus testing when it legalized adult-use cannabis in 2019 brought a change in tides for the remediation company. Suddenly, remediation was no longer viewed as a lesser grower’s best hope, but as a sometimes crucial step to protect a business’s crop.

How Ozone Works as a Cannabis Kill-Step

Willow’s technologies use a gaseous form of ozone, which the company’s research shows has a negligible impact (within the statistical margin of error) on cannabinoid and terpene content. In fact, cannabinoid concentrations may appear slightly higher after treatment as there can be a slight drop in relative water content from the process.

“In the food industry, you have to have a ‘six-log reduction’ to get your product on the shelf and to ensure that there are no pathogens,” Ellsworth said. A log reduction is a sterility measurement, where each one removes 90% of a microbial population. A six-log reduction takes a sample that has a million microorganisms down to near zero.

“That standard isn’t defined for cannabis right now,” she continued. “What [Willow does] is get your product under the testing thresholds for your state–in Colorado it’s 10,000 CFUs for total yeast and mold. Depending on your starting point of contamination and the treatment time you run, we can 98% of the time get you under that threshold so that you pass.”

Ellsworth said the term remediation has earned a bad rap in the cannabis industry and is a misconception that the company continues to educate on today. Instead, she is aiming to have cultivators view kill steps and decontamination as standard practices like in any consumer good. In the same way that all milk products sold at grocery stores go through pasteurization processes, “regardless if it has a contamination issue, [cannabis growers] should be treating everything,” she said.

That negative preconception of remediation led to many cultivators writing off Willow, but Ellsworth said the company has made improvements to its system and has developed different models that meet the needs of different-sized operations.

The WillowPure 5 system is the company’s smallest piece of hardware. With a capacity of 5 pounds of flower, it is designed for smaller operations. The WillowPure 20 is the company’s original system that the company now recommends for use on pre-rolls rather than flower products, although it can hold up to 20 pounds of bud if needed. “You can put thousands of pre-rolls on those shelves and then treat them,” Ellsworth explained.

The WillowPure360 is the company’s newest system. Launched in 2020, the main added feature is the rotating drum able to hold up to 20 pounds of whole flower and double the amount of trim. Having a drum toss the cannabis allows for better contact between the flower and the ozone, resulting in what Ellsworth said was the company’s “best kill rate.”

Growing Willow’s Service Tree

Cultivators interested in acquiring one of Willow’s pieces of hardware can only do so under a lease, and there are no secondary marketplaces for the system. Ozone being a potentially lethal gas when not used properly, “what I didn’t want to happen and what my team didn’t want to happen is see these WillowPure systems on the secondary market,” Ellsworth detailed. “That’s why we put this lease program in place…. If a cultivator doesn’t renew their lease, that machine comes back to us, we refurbish it, and we get it back into the market.”

The company leases its technology on 1- to 3-year contracts with prices ranging from $5,000-$7,000 per month, but each agreement is custom-tailored to meet the customer’s needs and scale. Maintenance and servicing also are included in the rental price, as is access to the company’s team of microbiologists for expert advice.

Willow Industries also offers microbial assessments, which Ellsworth said allows the company to be more than a product supplier to its customers, and instead become an integral part of a holistic approach to cultivation. “Our science team of microbiologists will go into your facility, do a full microbial assessment so you understand, as a cultivator, where is contamination coming from,” Ellsworth said. “We’ll swab all these different critical control points within your processes and then give you a very detailed report. If your water’s popping hot for yeast, if we’ve seen aspergillus in your growing medium, you’re gonna know all this stuff and can start making changes in relation to that so that you’re not seeing heavy contamination coming down the supply chain.”

Ellsworth noted that the fact she and her company are still around following her early struggles in getting the cannabis industry to understand the importance of having a kill-step is a sign that Willow Industries is around for the long haul. She shared that revenues between 2020 through 2022 grew at approximately 30% year-over-year. Combined with the $2 million raise, which it completed following its first cash-flow positive year in 2021, she believes Willow Industries is well-positioned to navigate the current market correction and capitalize on growth opportunities.

The company has already expanded into international markets with its dedicated cannabis solutions, having launched its products in Australia, and is looking to launch a software platform to further support its customers’ decontamination needs in 2023.

“We’re focused on growth–within the parameters that we can grow without spending all of our money,” Ellsworth said with a chuckle.