Trader Joe’s “Ts & Js Lemon Grapefruit Lime Tangerine Sour Gummies” have soured the palate of at least one consumer, according to a recently-removed Southern District of California lawsuit. Plaintiff Serena Wong, who filed her complaint against the grocery giant earlier this year, claims that the candies contain an undisclosed artificial ingredient, d-l malic acid, which enhances the candies’ tangy flavor. The label discloses the ingredient “malic acid,” which is in fact natural, but laboratory testing of commercial samples of the product showed the presence of the compound’s “d-l” form—“a synthetic petrochemical” that has “never been extensively studied for its health effects in human beings” according to the complaint. Wong claims the failure to declare the artificial flavor on the packaging and labelling the candies as “all natural” is unlawful, and she brought the putative class action suit against Trader Joe’s for violations of California’s Consumer Legal Remedies Act, unfair competition, false advertising, breach of express and implied warranties, and negligent misrepresentation.

Trader Joe’s removed the suit in May and was granted an extension until August to respond to the complaint.

Takeaway: The differences between which ingredients have been deemed “natural” versus “artificial” may seem minute—such as malic acid versus d-l malic acid—but advertisers should be wary not to open themselves to potential liability by mislabeling or ambiguously-labeling a product’s ingredients.