The Brief A class-action lawsuit claims Costco misled shoppers by marketing its rotisserie chicken as preservative-free. Plaintiffs allege the chicken contains sodium phosphate and carrageenan, which they say function as preservatives. Costco is facing a class-action lawsuit accusing the warehouse retailer of falsely advertising that its Kirkland Signature Seasoned Rotisserie Chicken contains no preservatives, according to court documents. The lawsuit, filed Thursday in the U.S. District Court for the Southern District of California, alleges that Costco’s in-store signage and website "create an overall net impression that the Rotisserie Chicken does not contain added preservatives." But the suit further claims those representations are false, arguing that "the Rotisserie Chicken is made with two added preservatives—sodium phosphate and carrageenan."