for mandatory disclosure of additives in beef, while others have expressed concerns about plant closures that occurred after the product received significant news media coverage. In December 2018, lean finely textured beef was reclassified as "ground beef" by The Food Safety And Inspection Service of the United States Department Of Agriculture. Production and content Finely textured meat is produced by heating boneless beef trimmings (the last traces of skeletal muscle meat, scraped, shaved, or pressed from the bone) to , removing the melted fat by centrifugal force using a centrifuge, and flash freezing the remaining product to in 90 seconds in a roller press freezer. The roller press freezer is a type of freezer that was invented in 1971 by BPI CEO Eldon Roth that can "freeze packages of meat in two minutes" and began to be used at Beef Products Inc. in 1981. The lean finely textured beef is added to ground beef as a filler or to reduce the overall fat content of ground beef. In March 2012 about 70% of ground beef sold in US supermarkets contained the product. It is also used as a filler in hot dogs produced in the United States. The recovered beef material is extruded through long tubes that are thinner than a pencil, during which time at the Beef Products, Inc. (BPI) processing plant, the meat is exposed to gaseous ammonia. At Cargill Meat Solutions, citric acid is used to kill bacteria such as E. coli and Salmonella. Gaseous ammonia in contact with the water in the meat produces ammonium hydroxide. The ammonia sharply increases the pH and damages microscopic organisms, the freezing causes ice crystals to form and puncture the organisms' weakened cell walls, and the mechanical stress destroys the organisms altogether. The product is finely ground, compressed into pellets or blocks, flash frozen and then shipped for use as an additive. Most of the finely textured beef is produced and sold by BPI, Cargill and Tyson Foods. As of March 2012 there was no labeling of the product, and only a USDA Organic label would have indicated that beef contained no "pink slime". Per BPI, the finished product is 94% to 97% lean beef (with a fat content of 3% to 6%) has a nutritional value comparable to 90% lean ground beef, is very high in protein, low in fat, and contains iron, zinc and B vitamins. U.S. beef