Every day, millions of Americans are likely putting something in their mouths that contains a substance called “meat glue” by critics of the food industry.

The additive with the unappetizing nickname is used to produce meats found in supermarkets, in local delis and in restaurants ranging from fast food to fine dining. Even vegetarian food isn’t exempt.

Marketing consultants and food scientists estimate – because no company will discuss sales figures – that anywhere from 11 percent to 35 percent of all packaged and sliced ham, beef, chicken, fish, pizza toppings and other deli products are enhanced, restructured or molded using the meat glue, which is made from one of two brands of protein adhesive.

Even though federal laws require labeling, a spot-check of meat purveyors and restaurant suppliers by Scripps Howard News Service found that almost no companies listed the substances among their products’ ingredients.

Further, 10 meat and cold-cut processors and fast-food outlets – including Tyson Food, Cargill Meats, McDonald’s and Arby’s – were contacted by Scripps, but all declined to discuss whether they used transglutaminase or blood-extract products, saying either that it was proprietary, or, if they did use them, it need not be reported because the binders were considered a “processing aid.”

Like the “pink slime” used as a cheap ground-beef filler, meat glue is not considered a health risk by federal food watchdogs. Nonetheless, consumers recently reacted with revulsion to the presence of pink-slime filler in ground meat, leading, ultimately, to the closing of three processing plants and the removal of the additive from some restaurants’ fare.

Whether or not meat glue will meet the same fate, the lack of disclosure is the same in critics’ eyes. “For decades, the meat industry has conveniently operated in the dark, not sharing the dirty details of their practices with the public, while the federal government looked the other way,” Michele Simon, a policy consultant for the Center for Food Safety, told Scripps.

“But now, consumers are demanding to know the truth about what they are. We need more transparency in a food system that puts profits before people.”

One of the two most common forms of meat glue used in the U.S. is Activa, a white powder form of a natural coagulant-like enzyme called transglutaminase. (The popular yogurt Activia has no connections to Activa.)

The other is Fibrimex, which is made of enzymes extracted from pig or beef blood by a process developed in the Netherlands. Both products were designed and sold, their advertising says, to bond pieces of protein or irregularly shaped meat so it can be cut and cooked evenly by the food-service industry.

Food scientists tell Scripps that the two cold-binding agents are used to reduce the use of sodium phosphate, sodium alginate, carrageenan, sodium caseinate and other chemicals that had been used for decades to form and mold meat.

Not knowing that Activa and Fibrimex are in certain foods can present problems for people with religious and dietary beliefs or special needs.

How are Jews, Muslims and others who don’t eat pork products going to know whether there are pig-blood extracts holding together their chicken or fish pieces? What about vegans and vegetarians who might not want to eat “meatless” hot dogs, sausage and luncheon meats containing bovine blood or the fermented enzymes?

“There may be economic adulteration going on here, and the (U.S. Department of Agriculture) or the (U.S. Food and Drug Administration) needs to look at whether laws are being violated,” says Tony Corbo, legislative representative for the national consumer group Food & Water Watch. “We are especially appalled that certain consumers’ religious beliefs may be unknowingly violated because food manufacturers are hiding what goes into the production of these binding agents.”

Meat glue first drew attention last year when an Australian video went viral on YouTube. It showed a meat specialist sprinkling white powder on pieces of fat, gristle and other waste beef, covering it in plastic wrap and chilling it. Hours later, the pieces had transformed into a long log of solid meat, which was then cut into expensive-looking tenderloins.

These cold-bonding agents are being used at the top and bottom of the food chain, from fine chefs at the high-end of the culinary workforce to cut-rate meat purveyors at the other.

Interviews by Scripps with more than 60 industry or academic food scientists, physicians and government-safety regulators revealed other, unanticipated uses for the meat-glue additives. These include imitation seafood, gyro meat, hundreds of different baked goods, tofu, pasta, vegetables, cereals and dairy products such as yogurt. And, they add, that use is growing. But, as with pink slime, you won’t find meat glue on a list of ingredients.

Over the past five months, Scripps checked more than 130 meats and deli products in Seattle, Milwaukee, Omaha and Denver that food scientists believed contained the adhesives mixtures. Only four of them – all bolognas – had the word “enzymes” on the ingredient label. But “enzymes,” “transglutaminase,” “thrombin” and “blood byproducts” were not listed anywhere on the labels for the remainder.

Government regulations are precise in how the public is supposed to be told when and what ingredients are added to food offered for sale in stores.

In 2000, when federal officials first granted permission for Ajinomoto to market the French-made transglutaminase in the United States, the USDA required that the company tell consumers they were buying “beef tenderloin formed with water and transglutaminase enzyme,” according to documents obtained by Scripps.

Ajinomoto balked and said it wanted to use words that didn’t mention transglutaminase. Instead, it wanted to say its products were “formed” or “re-formed” or made with enzymes as part of the product name, such as “formed beef tenderloin.”

Ajinomoto, the company that developed the sometimes-controversial flavor enhancer monosodium glutamate, or MSG, got its way and the USDA approved use of the less-foreboding language.

Similar precise language was created for the blood-product maker Fibrimex to use on its products.