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Web Date: April 16, 2012

Pink Slime

Ammonia’s the player in this beleaguered meat product
Department: Science & Technology
News Channels: Analytical SCENE, Biological SCENE, Environmental SCENE
Keywords: Pink slime, beef, food chemistry, ammonia
Chips of lean finely textured beef, also known as pink slime, in frozen form.
Credit: Beef Products

What a difference a few years make for South Dakota meat processor Beef Products Inc. In 2008, the Washington Post lauded the company’s process for eliminating bacteria from beef. For an industry haunted by the specter of Escherichia coli outbreaks from the 1990s, it seemed like a triumph of technology over nature. Today, though, that same process is being vilified by the media and the public. And the company’s marquee product, which it calls boneless lean beef or lean finely textured beef (LFTB), has become infamously known by the unappetizing name of “pink slime.”

The story of pink slime is a case study in what happens when companies that lack transparency clash with a public that wants to make well-informed food choices and balks at mysterious-sounding food-processing efforts.

The slime (or LFTB, depending on whom you talk to) comes from beef trimmings, says James S. Dickson, a food microbiologist at Iowa State University who has conducted studies in collaboration with Beef Products. After cutting a cow carcass into roasts and steaks, “you end up with these odd-sized pieces of meat,” which have high fat content and can be susceptible to bacterial contamination, he says. In the name of reducing waste in beef production, companies including Beef Products and agribusiness giant Cargill turned to chemistry.

At Beef Products, Dickson explains, technicians release the beef from the trimmings by heating trimmings to roughly 100 °F, which liquefies fat. They then separate the fat and protein with a spin on an industrial centrifuge. To kill bacteria, the protein portion is exposed to a puff of ammonia gas. Ammonia reacts with water in the meat to form ammonium hydroxide, raising the processed product’s pH to as high as 9.35, according to a 2001 Beef Products study obtained by the New York Times.

“Bacteria can’t tolerate extremes in pH and they simply die,” Dickson says. The resulting finely textured beef gets frozen and cut into small chips. When the finished product is blended with other trimmings to make ground beef, the level of ammonia that results is about 0.02 g for every 100 g of meat, Beef Products spokesman Rich Jochum tells C&EN by e-mail. That’s on par with other foods and is less than what’s contained in products such as salami and bleu cheese, according to the University of Michigan’s Risk Science Center, citing a 1973 analysis of foods’ ammonia content (Am. J. Clin. Nutr. 1973, 26, 487).

Beef Products founder Eldon Roth was the first to patent ammonia as a beef sanitizer, but companies have several ways of making finely textured beef—most methods use food-grade acids such as citric or lactic acids as antimicrobials.

This isn’t even Beef Products’ first time through the media meat grinder. A 2009 New York Times investigation revealed that its ammonia treatment didn’t always finish off bacteria. “While the pH enhancement process is very effective in eliminating pathogens, no process is foolproof,” Jochum wrote. The method “is only one step in a multihurdle food-safety system,” including a sample testing program used to improve the process and ensure contaminated products don’t reach consumers, he adds.

“We’re not in the habit of endorsing products or companies, but we’ve seen no reason to believe that the ammonia process itself is dangerous for consumers,” says Sarah Klein, a food-safety attorney for the nutritional watchdog Center for Science in the Public Interest.

“That’s not to say that American consumers want it,” Klein adds. Safety is one of many factors that can determine food choice, she explains. “The consuming public may say, ‘We don’t care if it’s safe, we don’t want it anyway.’” Plenty of other products represent the high-tech marriage of engineering and food, she says. “Pink slime is just the most well-known this month.”

In the aftermath of pink slime ire, Department of Agriculture officials on April 4 said they’ll grant requests from some meat producers to list lean finely textured beef as an ingredient on packaging. Federal officials had previously agreed with Beef Products that ammonia was a processing agent and didn’t need to be listed on labels, according to the 2009 New York Times story. It was a former scientist from USDA, Gerald Zirnstein, who coined the term “pink slime” in disgust over that decision.

“Food isn’t just about nutrition, just like politics isn’t just about policy,” says Robin D. Hanson, a professor who teaches health economics at George Mason University. “There’s just an ick factor about the kinds of things that go into our foods.”

Though it may be too late to mend pink slime’s image, Klein adds, “the industry could do a better job of educating consumers about the benefits of not wasting parts of an animal, to avoid the public outcry that happens when people feel they’ve been misled.”

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