Order a breakfast sandwich at virtually any fast-food restaurant, and the components are the same: some kind of bread, some kind of meat, and a pliable hockey puck of “egg.”

But if bakery chain Panera gets its way, restaurants won't be able to call those yellow patties “eggs” in the future. Last week, the company petitioned the Food and Drug Administration to update its 40-year-old definition of the word to exclude most of the processed egg products that have become popular with fast-food chains and food-service.

Calling these products “eggs,” Panera says, confuses consumers and gives an unfair marketing boost to companies that pump their egg products with fillers and additives.

It’s an argument that’s unlikely to gain traction at FDA — but that speaks to the challenges the agency faces in an increasingly inventive food market. As companies seek to meet consumer demand for cleaner, healthier or more convenient products, they’ve developed a wide array of new foods — like highly processed egg hockey pucks — that don’t fit neatly into FDA’s decades-old definitions.

That has prompted calls to rewrite or expand those rules, which limit how companies can describe their product on menus and in advertisements.

“Our industry would benefit from more guidance,” said Sara Burnett, director of wellness and food policy at Panera. “We don’t have clear rules on this, and it’s a matter of transparency and fair and honest labeling for consumers.”

Burnett said the egg issue came to Panera’s attention earlier this year, when the company was checking federal food-labeling requirements ahead of the launch of a new line of breakfast sandwiches. FDA has issued formal definitions for hundreds of food items, a consumer-protection measure that dates back to the 1906 Pure Food and Drug Act.

When Panera looked up the legal definition of the term “egg,” however, they came up blank: FDA rules actually specify that “no regulation shall be promulgated” to define “the food commonly known as eggs.” The rule has been on the books since at least 1977, far longer than most processed egg products available today.

An FDA spokesperson could not immediately find an explanation of the rule's origins. But the 40-year-old regulation has, Burnett said, limited Panera’s ability to differentiate its fresh eggs from the processed eggs sold by other restaurants.

Most fast-food and fast-casual chains — including heavyweights such as Taco Bell, Dunkin' Donuts and Starbucks — buy precooked, frozen egg patties to reheat on-site, or they cook their eggs from bulk liquid egg products. (McDonald's, the country's largest chain by sales, uses fresh-cracked eggs in its Egg McMuffins, though it uses liquid and pre-made eggs in some of its other breakfast items.)

Eggs are the main ingredient in these processed products, said Guy Crosby, a chemist who teaches food science at Harvard University. But they also frequently contain preservatives to extend shelf-life, colorants to approve appearance, and starches and gums to help the liquid flow evenly on hot pans.

Most consumers do not understand that's what they're ordering when they get an “egg” sandwich, Panera argues in its petition to the FDA. The company is asking FDA to restrict the term “egg” to products free of additives and most processing. Those breakfast-sandwich hockey-pucks would have to go by something different, like “egg product” or “egg patty.”

“When a consumer orders an 'egg,' they expect to get an egg,” said Burnett. “I don’t think consumers understand these other products that have five or more ingredients.”

Panera’s competitors dispute that allegation, as well as the petition itself. Even processed and liquid egg products are made from “real eggs,” they argue. And chain restaurants, including Dunkin' Donuts, Starbucks and Taco Bell, commonly disclose their ingredient lists on websites and in-store handouts.

“We couldn’t agree more with Panera that ‘people deserve to know what’s in their food and make the best choices for them based on this knowledge,’” Taco Bell said in a statement to The Washington Post. “That’s why Taco Bell was one of the first restaurant brands to voluntarily provide complete nutritional and ingredient information on our website 13 years ago.”

Experts say Taco Bell and the other companies have a point: There is no real mystery surrounding their eggs, since they already disclose the ingredients. While their egg products may include additives, they are still mostly eggs, Crosby said.

Mitchell Cheeseman, a former official in the FDA’s Center for Food Safety and Applied Nutrition who now advises food companies at the law firm Steptoe & Johnson, is skeptical the agency would take action on a petition like this one.

“The agency generally moves pretty slowly on these issues, because they have other public health issues to deal with,” said Cheeseman. “It’s not a priority if it doesn’t have a public health consequence.”

At the same time, FDA watchers acknowledge a larger issue: The agency's definitions for food products are increasingly out of date, and do not align with many new food products.

Egg products, such as processed liquid eggs that can last for six months or more, are one such example. But there are others: Recently, the dairy and plant-based food industries have locked horns over whether new soy, almond and rice beverages can call themselves “milk,” with both sides turning to FDA to clarify its dairy definitions.

Other commodity groups may push FDA for a new definition of “meat,” said Glynn Tonsor, an agricultural economist at Kansas State University, as companies develop lab-grown and plant-based versions.

The agency is also under pressure to regulate the health claims that food-makers put on product labels: FDA has never regulated the term “natural,” and the definition for “healthy” is so old that it excludes foods like almonds, olives and avocados. FDA is in the process of updating both, following years of petitions and lawsuits.

“Most of the standards of identity are decades old, but there’s never been a real consensus on them,” said Mel Drozen, who advises companies on FDA compliance as a partner in the law firm Keller and Heckman. “So FDA really hasn’t done anything except occasionally when pressed, and pressed hard.”

Change could be coming, however. In its strategic policy plan for 2018, FDA announced that it would focus on modernizing food definitions this year — a feat the agency has not attempted in earnest since the Clinton administration, Drozen said.

The move is intended to lower barriers to new-food product development, the agency said, as well as give consumers “accurate information.”

Whether eggs will rank among the chosen commodities is yet to be seen. (FDA said it will prioritize them based “on their public health value.”) But even if it isn't, Panera's Burnett said, the company believes it has succeeded in drawing attention to the issue.

“We hope that FDA seriously considers our petition,” she said. “But even if they don’t … we’re happy with the conversation we’ve created.”

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