A California cannabis company stopped by Minnesota this year to drum up business by testing the potency of about a dozen THC-infused beverages.

Shockingly, at first glance, several brands had too much or too little of the high-producing compound, the company Vertosa reported in April.

With four-packs of hemp-derived THC seltzers selling for $15 to $30, even one missing milligram of THC can lead to a letdown for consumers paying a premium for their buzz.

"Without accurate labeling, consumers are at risk of feeling little to none of the desired effects, or worse, consuming more than intended," Vertosa and third-party testing lab Anresco said in the report.

As the young industry enters a new era of regulation and mainstream acceptance, THC beverage makers will be held to increasingly higher standards compared with the early experimental days.

Many in the industry say Vertosa's results are in line with expectations of "potency stability."

Two of the drinks tested in the study had undetectable levels of THC, but those were also the only products that were more than six months old. The other 14 beverages tested mostly within the 10% margin of error — the standard accepted by industry professionals.

Experts say that's about as accurate as testing can get with such a small amount of a substance; some potency decay is expected given the science of cannabis in beverages is still being developed.

"There is a potency loss over time, and what that looks like is so variable based on the formula, based on the format," said Kyle Marinkovich, founder of Northern Diversified Solutions in Burnsville, which turns hemp into CBD and THC isolates and emulsions for use in food and beverages.

Jon Eager, lab director at White Bear Lake hemp extraction company Superior Molecular, said oxygen and light are likely the "biggest culprits."

"Everybody needs to do their own independent studies and bite that bullet," Eager said about brands investigating potency stability. "That is unfortunately expensive or time consuming, but as a product maker, it's your responsibility."

Minnesota charted a new course in 2022 by explicitly legalizing food and drink with low doses of THC derived from hemp, which unlike marijuana was already legal at the state and federal level. The past year has seen an explosion of THC gummies and beverages from dozens of brands, especially breweries.

Now that those products can be sold at Minnesota liquor stores, they will be more visible and readily available — and consumers will be picking winners and losers based on how well and consistently the products deliver their promised effects.

"We've started to see where the market has started to penalize some of the bad actors," Marinkovich said.

Consumers should scan those QR codes required on THC products to ensure brands are providing full and recent test results. Every new batch of products needs a new round of testing.

A Star Tribune review of a dozen recent lab tests for Minnesota-made cannabis beverages showed variability of up to 1 milligram — 20% — in tested THC content versus what the label says. How that might affect a consumer's high will be different for every person.

"I would say to consumers that have concerns: The proof is in the pudding," Marinkovich said. "If it's meeting the expectation that you're getting value out of that $5 can, then amen."

Potency loss

Despite marijuana being legal in some states for more than a decade, THC beverages have been slow to take off nationally. THC is not water soluble, so companies have been coming up with various methods of emulsifying tiny particles of the chemical, which can also speed up absorption and the onset of a high.

But when those emulsions mix with carbonated water and other ingredients, some unwanted chemistry can happen.

Beverage companies have long battled a phenomenon known as "scalping," where flavors and aromas stick to the plastic liner inside aluminum cans. Some say this can happen with cannabis compounds, which Fulton Brewery has used as a selling point for its glass-bottled THC drinks.

"Depending on the liner material you use, CBD or THC can adhere to the liner [in aluminum cans]," said Janet Johanson, CEO of St. Paul-based packaging and ingredient supplier BevSource.

As a result, brands are in some cases adding a little extra THC and waiting for a decline in dosage to level off before putting products on shelves. The industry is still in its infancy, Johanson said, and has a lot yet to learn.

Scott O'Malley, CEO of the Clr!ty brand of THC beverages, said scalping wasn't an obvious issue at the start of the hemp beverage boom, but he has found "it does make a difference what kind of can you use."

O'Malley said he pulls products at regular intervals to test for potency loss after canning. He had to recall a batch after a follow-up test showed potency had dropped by half.

Though the Minnesota Department of Health is now in charge of regulating the market, in many cases it remains up to individual companies whether they would do the same in a similar situation.

Falsifying test results can be punished by a fine of up to $3,000 and up to a year in jail. State law requires a hemp-derived THC product "contains the amount or percentage of cannabinoids that is stated on the label of the product."

Superior Molecular founder John Dugas said the process of making THC-infused beverages, which varies among producers, will have the greatest impact on potency stability.

"We should be incentivizing companies to tighten quality control in this industry," he said. "Our job is really to go in and analyze the situation from a production standpoint because everybody has limited resources and different canning lines."

Vertosa CEO Ben Larson said oxidation of THC molecules is a major factor.

"If not properly treated, THC will naturally degrade over time, and depending on the formulation of the beverage, this can happen rather quickly," he told the Star Tribune.

Overall, Vertosa's report struck an upbeat tone, given the new and largely unregulated nature of the business.

"Many brands did have accurate labeling and demonstrated consistent potency across multiple products," Vertosa's report said.

"These brands are a testament to the potential of the industry and show that it is possible to create high-quality, accurately labeled hemp-infused beverages."