(abcnews)
Gerald Zirnstein grinds his own hamburger these days. Why? Because this former United States Department of Agriculture scientist and, now, whistleblower, knows that 70 percent of the ground beef we buy at the supermarket contains something he calls “pink slime.”

“Pink slime” is beef trimmings. Once only used in dog food and cooking oil, the trimmings are now sprayed with ammonia so they are safe to eat and added to most ground beef as a cheaper filler.

It was Zirnstein who, in an USDA memo, first coined the term “pink slime” and is now coming forward to say he won’t buy it.

“It’s economic fraud,” he told ABC News. “It’s not fresh ground beef. … It’s a cheap substitute being added in.”

Zirnstein and his fellow USDA scientist, Carl Custer, both warned against using what the industry calls “lean finely textured beef,” widely known now as “pink slime,” but their government bosses overruled them.

According to Custer, the product is not really beef, but “a salvage product … fat that had been heated at a low temperature and the excess fat spun out.”

The “pink slime” is made by gathering waste trimmings, simmering them at low heat so the fat separates easily from the muscle, and spinning the trimmings using a centrifuge to complete the separation. Next, the mixture is sent through pipes where it is sprayed with ammonia gas to kill bacteria. The process is completed by packaging the meat into bricks. Then, it is frozen and shipped to grocery stores and meat packers, where it is added to most ground beef.

The “pink slime” does not have to appear on the label because, over objections of its own scientists, USDA officials with links to the beef industry labeled it meat.

“The under secretary said, ‘it’s pink, therefore it’s meat,’” Custer told ABC News.

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