Costco sued by customer who claims one dish’s no preservatives’ promise is a lie

A Costco customer has sued the big-box brand,claiming it misled shoppers by marketing a popular frozen pasta product as preservative-free despite it allegedly containing a chemically manufactured additive.

The proposed class-action lawsuit, filed by Sydney Turner in a California federal court on April 29, centers on Kirkland Signature Five Cheese Tortelloni with Parmigiano Reggiano.

According to legal documents seen by Top Class Actions, the product features a prominent “no preservatives” claim on its packaging, which Turner alleges is contradicted by the inclusion of manufactured citric acid on the back ingredient panel.

Turner purchased the frozen tortelloni in December 2023, relying on the marketing claim, according to the complaint. She alleges that she would not have purchased the product, or would have paid less for it, had she known it contained an industrial preservative.

The lawsuit argues that manufactured citric acid is produced through industrial fermentation and heavy chemical processing rather than being naturally extracted from fruit, which the complaint states is not commercially feasible.

Turner alleges that the citric acid used in the product is manufactured using a genetically modified black mold called Aspergillus niger, citing studies and reports that link the ingredient to potential health risks.

Turner is seeking class-action certification on behalf of a nationwide class of consumers who purchased the product, as well as subclasses of consumers in certain states. The lawsuit seeks damages, fees, costs and a jury trial.

The complaint follows a separate class-action lawsuit filed against Costco earlier this year.

In March, a proposed class-action lawsuit filed in Washington federal court accused the retailer of unjustly keeping financial benefits from federal import tariffs that were struck down by the U.S. Supreme Court.

The dispute stemmed from duties imposed by the Trump administration in February 2025. According to the complaint, Costco raised prices on imported goods to pass the tax burden directly to shoppers, but failed to commit to refunding those same customers after the Supreme Court ruled the tariffs unlawful in February 2026.