Meat slurry is a broad, informal term for meat products that have been mechanically processed into a paste-like or semi-liquid form. It most commonly refers to two specific products: mechanically separated meat (MSM), where bones with attached meat are forced through a sieve under high pressure, and lean finely textured beef (LFTB), the product at the center of the 2012 “pink slime” controversy. Neither product looks like the cuts of meat you’d recognize at a butcher counter, which is exactly why the term “slurry” stuck.
How Meat Slurry Is Made
The process differs depending on the type of meat and the end product, but the basic idea is the same: extract usable protein from parts of the carcass that can’t be sold as conventional cuts. For LFTB, beef trimmings that include fat, small pieces of meat, and bits of connective tissue are heated to about 100°F. The warm mixture is then spun in a centrifuge, which separates the lean meat from the fat and connective tissue. The result is a product that’s 94 to 97 percent lean beef. Roughly 10 to 12 pounds of this lean beef is recovered from each carcass.
Mechanically separated poultry (used in hot dogs, chicken nuggets, and some deli meats) works differently. Bones with residual meat are pushed through a machine that forces the soft tissue through small holes while leaving the bone behind. The result is a smooth paste with a texture nothing like ground meat.
In the case of LFTB, the separated lean beef is treated with a small amount of ammonium hydroxide gas to raise its pH and kill bacteria. This step became one of the most controversial aspects of the product when it entered public awareness. The USDA considers ammonium hydroxide safe for use in food processing, and it appears in a range of other foods including baked goods and cheese. Still, many consumers were unsettled to learn it was being used on beef products without clear labeling.
Where It Ends Up in the Food Supply
LFTB is not sold directly to consumers as a standalone product. Instead, it’s blended into conventional ground beef at a rate of no more than 15 percent. Because the recovered beef is so lean, adding it to fattier ground beef creates a leaner final product while maintaining the texture people expect. Before the 2012 controversy, this blending was standard practice across much of the U.S. beef industry, and the USDA did not require any special labeling. Ground beef containing LFTB was simply labeled “ground beef.”
Mechanically separated poultry is more visible on ingredient lists. If you check the label on hot dogs, bologna, or certain frozen chicken products, you’ll often see “mechanically separated chicken” or “mechanically separated turkey” listed. The USDA requires this disclosure for poultry. Mechanically separated beef, however, has not been permitted in human food since 2004 due to concerns about bovine spongiform encephalopathy (mad cow disease). LFTB uses a different process and remains legal.
The 2012 “Pink Slime” Backlash
LFTB had been used in ground beef for years with little public awareness. That changed rapidly in early 2012. In January, McDonald’s, Burger King, and Taco Bell announced they would stop using LFTB in their beef products. By March, the issue had exploded. Celebrity chef Jamie Oliver launched a petition at StopPinkSlime.org that drew over 258,000 signatures, and 41 members of Congress called for an end to the product in school lunches. A separate petition on Change.org pressured the USDA directly.
The fallout was swift and severe. Major grocery chains including Kroger and Safeway pulled LFTB products from their shelves. Beef Products Inc. (BPI), the primary manufacturer of LFTB, closed three of its four processing plants. The USDA responded by giving school districts the option to order ground beef with or without LFTB, and approved voluntary labeling so producers could mark their products as either containing LFTB or being “LFTB free.”
The debate split along predictable lines. Former USDA microbiologist Gerald Zirnstein, who had originally coined the term “pink slime,” called the product “economic fraud” and “a cheap substitute” for fresh ground beef. The beef industry countered that LFTB was simply lean beef recovered through an efficient process, nutritionally equivalent to any other ground beef. Public health officials at the USDA maintained that both LFTB and the ammonium hydroxide treatment were safe. Consumer sentiment, though, had already shifted. Surveys from 2012 showed more than 80 percent of respondents were thinking about food safety, with over 50 percent specifically worried about meat.
Safety and Bacterial Risk
One of the core concerns about meat slurry products is that processing creates more surface area for bacteria to grow. A whole muscle cut of beef, like a steak, has bacteria primarily on its outer surface, which gets killed during cooking. When meat is finely ground or mechanically separated, surface bacteria get mixed throughout the product, which is why ground beef needs to be cooked to a higher internal temperature than a steak.
The ammonium hydroxide treatment used in LFTB production is specifically designed to address this risk. Research on ammonium hydroxide brines shows they reduce counts of cold-tolerant bacteria, general bacteria, and gram-negative bacteria (the category that includes E. coli and Salmonella). Large-scale testing of processed beef products has generally found low pathogen rates. A Canadian study testing nearly 1,000 samples of mechanically tenderized beef found zero instances of dangerous E. coli O157:H7, compared to a 0.2 to 0.3 percent detection rate in conventional beef cuts tested in earlier U.S. studies.
That said, the safety picture depends heavily on the specific manufacturer and their quality controls. The 2012 controversy wasn’t primarily about documented illness outbreaks. It was about transparency: consumers didn’t know this product was in their food and felt they should have been told.
Nutritional Differences
Nutritionally, LFTB is leaner than most ground beef. At 94 to 97 percent lean, it has less fat than standard 80/20 or even 90/10 ground beef. When blended at the permitted 15 percent ratio, it modestly reduces the overall fat content of the final product. The protein content is comparable to conventional ground beef, though LFTB does contain more connective tissue protein, which is lower in nutritional quality than muscle protein.
For mechanically separated poultry, the nutritional picture is different. The high-pressure process can incorporate small amounts of calcium from bone fragments, and the resulting paste has a different protein and fat profile than hand-deboned meat. It’s a nutritionally adequate protein source, but it’s not equivalent to a chicken breast.
How to Know If It’s in Your Food
Labeling has improved since 2012, but it still isn’t fully straightforward. The USDA approved voluntary labeling for ground beef with or without LFTB, meaning some producers disclose it and others don’t. If a ground beef package doesn’t say “LFTB free” or “contains no finely textured beef,” there’s no guaranteed way to tell from the label alone. Buying from a butcher who grinds meat in-house, or choosing products explicitly labeled as free from LFTB, are the most reliable options if you want to avoid it. For products like hot dogs and deli meats, checking the ingredient list for “mechanically separated” chicken, turkey, or pork will tell you what you need to know.