For the better part of two decades, before it was dubbed “pink slime,” this beef byproduct was nothing more than a mild-mannered staple in fast food burgers, tacos in school lunches and ground beef stocked in supermarket freezers.

Federal regulators never sounded safety concerns about it. No one directly linked it to foodborne illnesses or outbreaks. In fact, many food safety activists praised it as a technological marvel in the dangerous world of raw meat.

That’s why federal officials and the family-owned company that makes this product were slack-jawed when a public backlash erupted last month against what the industry calls “lean finely textured beef.”

None of the usual suspects caused the uproar, even though a few had tried. Instead, the unlikely source was a Texas mom eager to improve school food. Early in March, from her kitchen in a leafy Houston neighborhood, Bettina Elias Siegel sounded off on her blog, The Lunch Tray. She urged readers to “put a stop to pink slime” in school lunches and hastily launched an online petition before taking off for the day’s errands.

Eight days later, the signatures topped 200,000.

“I think you all know that I didn’t have the slightest clue what I was about to unleash,” Siegel wrote on her blog.

People, it seems, who for years gobbled down “lean finely textured beef” sat upright when they saw “pink slime.”

The moniker went viral. The “yuck” factor repulsed consumers. Supermarket chains – including Safeway, Kroger and Food Lion – abandoned the product. Wendy’s took out newspaper ads assuring customers that it never has used the stuff. Even the plodding government bureaucracy leaped into action, granting schools the choice to stop using it in lunches next year. Systems big and small, including public schools in Montgomery and Fairfax counties, opted out.

The episode damaged the fortunes of Beef Products Inc., the producer in South Dakota, forcing it to suspend operations in three of its four plants, though it pledged to keep paying its workers for now. A meat processor in Pennsylvania, AFA Foods, filed for bankruptcy protection this month, citing reduced demand for lean beef as a factor. Meanwhile, ground beef sales in March hit a 10-year low for the month, just as the grilling season was about to take off.

The dramatic fallout signals yet again the power of social media to change the way political actors and businesses respond to public pressure, leaving them all vulnerable — for better or worse — to reputational slights. Some consumer groups watched the events unfold with a mix of admiration, jealousy and perhaps remorse.

“It’s substantively not the most critical health issue, yet it was framed in such a way that the public outcry actually changed food policy in a matter of weeks,” said Sarah Klein, a lawyer at the Center for Science in the Public Interest. “If we could figure out the formula and apply it to serious public health issues, that would be amazing.”

The yuck factor

The phrase — pink slime — was born in a 2002 e-mail.

Gerald Zirnstein, a USDA microbiologist at the time, came up with it in an exchange with his colleagues. Seven years later, the e-mail emerged in a New York Times article that questioned the product’s safety.

Then nothing much, until last April.

That’s when celebrity chef Jamie Oliver thrust pink slime back into the spotlight on his nationally televised show, “Food Revolution.” Before a live audience, Oliver took a chunk of beef trimming and demonstrated his take on how the product is made: He spun the trimming in a washing machine, doused it in kitchen cabinet ammonia and then a splash of water.

Drain and mince. The audience gasped.

“We’re taking a product that would be sold in the cheapest form for dogs, and after this process we give it to humans,” Oliver told them.

McDonald’s, for one, stopped using it soon after.

Siegel, a Harvard-educated advertising lawyer turned blogger and freelance writer, had flagged readers to the New York Times article as well as Oliver’s show, though she concluded that his demonstration was over the top.

Fast forward to last month, when Siegel spotted a story in TheDaily.com that rehashed the issue. She realized that USDA had not abandoned pink slime in school lunches. She fired off the petition.

The next day ABC News launched a series on pink slime, and the story really took off. “Pink slime” shot up as one of the most popular search terms on the Internet. By day six, Siegel was operating on caffeine and adrenaline to keep up. (“I am one jittery, freaked out blogger,” she wrote.) Nine days into it, USDA announced its school choice decision.

Along the way, when Siegel was feeling especially overwhelmed, Oliver re-emerged with a plug for her petition.

“I happened to glance at Tweetdeck and saw a tweet from Jamie saying ‘WELL DONE@thelunchtray!’ and sharing the petition with his 2 million-plus followers,” Siegel said in an interview. “I felt like the cavalry had arrived.”

And now they’ve reached the halls of Congress. Lawmakers are demanding that the USDA stop schools from serving pink slime in lunches. They want companies to start labeling meat that contains the product, and some firms voluntarily agreed to do so.

‘Dude, it’s beef’

Eldon Roth, BPI’s founder, took out a full-page ad in The Wall Street Journal to decry the “campaign of lies and deceit” waged against his company. But he’s declined to comment for this article or any other.

Besides, Roth is not so smooth in interviews, his friend David Theno said.

“Public speaking is not his forte. He’s kind of a country boy,” said Theno, a food safety consultant credited with revamping Jack in the Box after the chain’s undercooked hamburgers killed three children in the early 1990s. Theno is now advising BPI. “He’s brilliant, but he’s not the kind of guy in today’s five-second sound-bite world that you put on camera.”

With a high school degree, Roth built a refrigeration business in 1981 that catered to meat companies. A decade later, BPI was the first to commercially sell lean finely textured ground beef using a technique of his devising that separated the meat from fatty trimmings.

Roth, who worked in milk and ice cream factories early in his career, borrowed heavily from dairy plant technology when he created a process to reclaim the bits of beef left clinging to the trimmings after a cow carcass is cut up to make steak.

BPI buys the refrigerated trimmings from slaughterhouses. It grinds them, warms them to slightly below the body temperature of a live cow, and then spins them at high speeds to cull the beef. The lean meat is then flash-frozen and sold to meat processors, enabling those firms to meet increased demand for lower fat grinds.

The company began using ammonia gas in 2001, with the USDA’s blessing. When the gas hits the water in the meat, it turns to ammonium hydroxide and kills bacteria, the firm said. Through the years, some BPI critics balked at the safety claims and dismissed the meat as a salvage product that does not meet the government’s definition of ground beef.

The New York Times report found that USDA initially did not test BPI’s beef, figuring the ammonia made it pathogen-free. Federal school lunch officials tested it anyway, found E. coli and salmonella numerous times between 2005 and 2009, and pulled it before it was served.

But when the most recent controversy erupted, many rallied to the company’s side.

USDA officials vouched for BPI’s meat. They said it has never been directly linked to illnesses or outbreaks since the government started testing it in December 2009. Of 7,000 samples that BPI provided to USDA school lunch officials in the past two years, none has tested positive for Salmonella or a deadly strain of E. coli, a government spokesman said.

Bill Marler, a Seattle lawyer who has built a business out of suing meat companies, said BPI’s lean beef is safe enough. “It’s not any more or less dangerous than anything else in hamburger,” Marler said.

Nancy Donley’s only child died from an E. coli infection. Yet the consumer activist also stands by the beef product. “It just sounds gross to people, but at the end of the day it’s beef,” she said. “Nothing is 100 percent safe ... but this product is misunderstood.”

Ammonia, BPI’s defenders point out, is a naturally occurring chemical in the body that’s added to other foods. It’s used as a leavening agent in crackers, for instance. Very early in the cheese-making process, a tiny amount of ammonium hydroxide can be added to reduce acidity or encourage cultures to grow.

The American Meat Institute estimates that if the lean finely textured beef disappears, it would take another 1.5 million more cattle per year to offset the loss. Even before the pink slime controversy, the meat industry was struggling. Ground beef sales, including trimmings, fell 11 percent last month to 38 million pounds, a 10-year low for that month, according to a Bloomberg analysis of government data.

The governors of Iowa, Texas and Kansas — home to BPI’s shuttered plants — say this is a lot of hoopla. They recently toured one of the firm’s factories and scolded the news media for hyping the issue. Iowa Gov. Terry Branstad accused the company’s critics of launching a “smear campaign.” The threesome even came up with their own catchphrase: “Dude, It’s Beef.”

Then, in front of the cameras, they chowed down on hamburgers.