I need to Write a new release for the center of science in the public interest. The idea is to present/support Your party's interest. We will assume that a lawsuit has not entered the dispute, so the contest will be a war of words, or news releases.
Based on this -
To force quaron to place adequate labels on their food products you can threaten their profit margins. By outreaching to major publi health advocates and spokesman(Dr. OZ) you cna run similar health compaigns as the American Legacy Foundation did to cause awareness of tabacco related problems(the guys who run all the TRUTH commercials). This can include distribution of "Shopping healthy" food pamphlets available to open public, preferablly close to where the foods will be distributed. Since listing the companies individual name could be considered deformation of character or slander the company can list alternatives to their food product that do not contain the fungus. A large enough campaign could severely threaten the product Quorn puts out by reducing their market share. This would in effect give Quorn the option to either place a label that may or may not cause a loss of potential profit or face an ad campaign that will definitely decrease their profit.