HOUSTON -

When you hear the words "pink slime" these days, you might feel a little queasy. Local 2 Investigates is getting to the bottom of the claims to find out what the "mystery" meat really is.

It's the name given to a type of beef we've heard all sorts of things about -- that it's meant for dog food and it's washed in a pink ammonia liquid to make it more palatable, among other things.  

It's sold in grocery stores, served at restaurants and earlier this month we learned public schools are feeding it to children. 

The "pink slime" scandal has spread like wildfire online. Reports say it is a meat filler made up of pieces of connective tissue and tendons that were scooped off the slaughterhouse floor and ground up, washed with a type of ammonia and then blended into the ground beef we all eat.

But there are a few things those in the meat industry want you to know.

"This is not a filler. It's not an additive. It's beef," said Janet Riley of the American Meat Institute. "So when we put beef on the label, we are being truthful."

"There's nothing on the floor or anything that's scooped up or anything like that," said Dr. Jeff Savell of Texas A&M's Meat Sciences Department.  

The American Meat Institute said the product everyone is talking about is called "lean finely textured beef." It starts as pieces of fatty meat left over after a cow is butchered for the better pieces of steak. 

Riley said the pieces of meat would be very difficult to remove from the fat efficiently. It's why 20 years ago a South Dakota company patented a technology that allowed it to heat up the fatty chunks to help separate the fat from the lean beef.

"We put those trimmings into something like a salad spinner or a centrifuge and that actually melts the fat away and leaves the 95-percent lean product," Riley explained.

Those smaller pieces are then packed together and treated with ammonia hydroxide to kill any bacteria.

"It's a puff of ammonia gas. It's not some sort of wash," Riley said. 

Local 2 Investigates wanted to know, just like you, why ammonia is used. If it's just more beef, why does it need to be treated with ammonia when the rest of the meat isn't?

Here's how the United States Department of Agriculture explains it: The source of most salmonella and E. coli comes from the hide of cows because they lay in their own feces. When the cows come into processing plants, workers do their best to keep the hides away from the carcass, but because most of that "lean finely textured beef" comes from areas close to the hide or the exterior of the cow, they said it's necessary to treat it with that ammonia hydroxide to kill the bacteria.

"I think the public outcry over pink slime has shown that consumers do want to know whether this stuff is in their ground beef, and they should have a choice about whether or not to purchase it," said Sarah Klein with the Center For Science in the Public Interest.

School districts across the nation couldn't ignore the outcry from parents.

"Certainly, we heard loud and clear from parents within HISD that it was important to them," Houston Independent School District's Food Services Administrator Brian Giles said.  

Since the "pink slime" scare started circulating, the United States Department of Agriculture decided to let schools choose whether to buy ground beef with or without the lean beef trimmings. HISD said that after checking with all of its vendors, it determined that the beef the district purchased from private vendors in years past did not contain any of the lean beef trimmings. It has elected to continue purchasing beef without the trimmings in the future.

"I think it's a pretty easy decision for us," said Giles.  

HEB, Fiesta, Costco and Whole Foods said its stores never carried the product. Kroger, Randalls andTarget pulled it and said they won't carry it any longer. Walmart said it will begin offering freshly ground beef that does not contain lean finely textured meat as quickly as possible.

Since the USDA doesn't require the beef to be labeled any differently, the only way to know you aren't getting it is if you buy beef with the "USDA organic" label.

The South Dakota company that makes the trimmings just closed three of its plants this week, laying off 650 employees because of the decreasing demand for its product. 

The American Meat Institute said if the technology to make lean finely textured beef was no longer used, the industry would need approximately 1.5 million cows a year to replace the meat currently generated from the process.