Starbucks says it doesn't add potassium to its Dark French Roast coffee after another coffee company accused it of mislabeling the product

Starbucks is pushing back against a North Carolina coffee company's complaint about Starbucks' Dark French Roast coffee.

• A coffee company filed a complaint claiming Starbucks adds potassium to its Dark French Roast coffee.
• The complaint says the alleged potassium levels means Starbucks is selling misbranded food in North Carolina.
• Starbucks said it doesn't add any potassium and the complaint is "without merit."

Starbucks is pushing back against a North Carolina-based coffee company's complaint that claims the amount of potassium in Starbucks Dark French Roast coffee "significantly exceeds the levels of potassium" that naturally occurs in coffee.

Starbucks said the complaint is "without merit."

Puroast Coffee Company, a roaster and seller of low-acid coffee, filed the complaint with the North Carolina Consumer Protection Division in September claiming that independent laboratory test results show Starbucks Dark French Roast coffee sold in retail stores "is at over 14 standard deviations above the respective average" of potassium content in raw coffee beans. "Even at the extremes," the amount of potassium doesn't usually deviate beyond five or six from the average, the complaint said.

"We are aware of the complaint Puroast has filed with the North Carolina Consumer Protection Division and believe it is without merit," a Starbucks spokesperson said in a statement shared with Insider. "We do not add potassium to Starbucks Dark French Roast coffee. Potassium is naturally occurring in coffee. Further, we are confident that the labeling for our Dark French Roast coffee is fully compliant with all U.S. Food and Drug Administration labeling requirements."

Kerry Sachs, CEO of Puroast, told Insider that the company discovered the amount of potassium in the Starbucks Dark French Roast during routine testing of different brands of coffee in the company's lab that it does about once a month.

In March 2022, Sachs said a test showed an "abnormally" high level of pH in the Starbucks coffee. A higher pH level means the coffee has lower acidity, he said. While coffee usually has a pH balance around 5, the Starbucks coffee was allegedly showing a pH of 5.7 to 5.8, or about 70% less acid than regular coffee, Sachs said.

"We thought it was a mistake, it was odd, it kept showing up," Sachs said.

Puroast sent its results to North Carolina Agricultural and Technical State University to confirm its results, which the university did, Sachs said.

Taka Shibamoto, professor emeritus of environmental toxicology at the University of California Davis Coffee Center, told The New York Post that the finding in the complaint "is strange and hard to believe." 

"A company like Starbucks must know the regulations," Shibamoto told the NY Post, adding that if the findings of the complaint are true, potassium might have been added to the coffee for taste or to lower its acidity.

The complaint accuses Starbucks of failing to disclose that potassium is added during production of its Dark French Roast coffee, and labeling it as "100%" coffee means the company has and "is currently selling and distributing, a misbranded food product within the State of North Carolina."

The North Carolina Department of Agriculture is currently reviewing the complaint, a spokesperson for the department told Insider.

Sachs said Puroast is calling on Starbucks to add a label disclosing any added potassium. He said he hopes the complaint encourages a standard to be developed for low-acid coffee.