What are hot dogs actually made of? There can be beef, pork, chicken and ... other stuff

We love hot dogs – especially on National Hot Dog Day. But we've all heard those stories about what might go into them.

Do they contain scraps from the meatpacking plant floor, or pig snouts and other body parts – or even human DNA?

Upton Sinclair's heralded exposé on the meat industry "The Jungle," released as a novel in 1906, detailed how collected scraps from the floor – including meat, sawdust and anything else on the floor – were used in making sausages. The book led to federal meat inspection laws, which prohibited that practice.

As those laws were refined, tougher labelling standards required increasingly specific listings of ingredients in hot dogs and other processed meats. Any hot dog or sausage using organ meats – or other parts such as head meat, tongue, lips, snouts – must be labelled as including variety meats.

"Any 'weird' ingredient that is put into a product must be labeled as such to inform the consumer of the item," said Jonathan Campbell, an associate professor and extension meat specialist at Penn State University. "It is impossible to make a high quality hot dog or frankfurter with sub-par raw materials."

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Pig snouts and cheek meat and "other seemingly weird” meat ingredients may be used in making traditional products such as souse and head cheese, Campbell said. "These ingredients are clearly labeled on that product and are not put into sausages like a frankfurter," he said.

And experts challenged the 2015 report that found human DNA in 2% of the 345 samples as likely shoddy research. "It's just unfounded," said Davey Griffin, professor and meat specialist for the Texas A&M AgriLife Extension Service. "Even in small plants, you don't touch anything without gloves on."

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As inspection and quality control standards increased, hot dogs became a menu mainstay in kitchens and ballparks – and earned an exalted place at cookouts and gatherings on holidays such as the Fourth of July.

Americans ate about 3.7 billion hot dogs in the 12 months ending May 2022, according to The NPD Group, a research firm. Most of those – 3.1 billion – are eaten at home, NPD says.

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Hot dog ingredients: They're made of meat ... and other stuff

The main ingredient in hot dogs is meat, and that can be beef, pork, or poultry (typically chicken, but some are made with turkey).

What kind of meat? Well, the process starts with selected meat trimmings – if you use your imagination, you might wonder what all that might include. The truth is not as unpalatable as you might think.

Trimmings are "those little bits and pieces that are accumulated" as steaks and roasts are cut and prepared for sale at your local meat counter or market, Griffin said. "It's the same thing we would use for ground beef or ground pork, it is just chopped to a much finer texture."

Similarly, chicken trimmings can be leftover from separating the chicken into thigh and breast parts.

In addition to meat trimmings, hot dogs can also contain up to 15% of mechanically-separated pork and poultry, which are transformed into a paste-like meat product when bones with edible meat attached to them are forced through a sieve to remove the bones. The result is sometimes referred to, not so respectfully, as "white slime."

You may remember "pink slime," the description ABC News gave Beef Products Inc.'s liquified beef product in a 2012 report. The meat processor filed a defamation suit against ABC News and reached a settlement in 2017. Three years ago, the USDA also told the company it could call the product "ground beef."

Back in May, something resembling pink slime, described by police as hot dog filler, spilled across Interstate 70 in Pennsylvania after a truck crash – bringing the substance to attention again. So some hot dogs could use this filler as an ingredient too.

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You should not find any bone fragments in hot dogs. During the creation of mechanically-separated pork and poultry, the machinery cannot crush or grind the bones; they must be removed basically intact, the USDA says.

Hot dogs or other meats, such as bologna, made with mechanically-separated pork, cannot contain more than 150 milligrams of calcium per 100 grams of the product. And any use of mechanically-separated meat must be specifically declared on the label, Griffin said.

Trimmings are ground, similar to how ground beef is made. Then, all meats are folded into a chopper along with any spices and other ingredients which could include beef stock, corn syrup, sugar, salt, spices, garlic puree, starch, water and ice. Hot dog manufacturers must list all the ingredients – such as non-meat binders and extenders including nonfat dry milk, for instance, or soy protein – on the product's label, the USDA says.

A hot dog may not contain more than 30% fat or no more than 10% water, or a combination of 40% fat and added water, according to the Department of Agriculture.

The mixing results in a batter-like substance called an emulsion, which is pumped into long strings of casings, which are twisted to make the hot dog shape. (Some hot dogs do use natural casings, which are typically made from sheep intestines.)

If you are curious about what the batter looks like – and see meat trimmings being processed – you can watch a video produced by the National Hot Dog and Sausage Council, posted on YouTube in 2014. The video about how hot dogs are made did make some viewers' stomachs churn, based on the posted comments. But others found the video informative.

The formed hot dogs are then put through an oven to cook, and perhaps be smoked. This process binds the lean and fat particles together in a matrix, Griffin said. After they are cooled, the casings are removed and the hot dogs go through a production line to be packaged.

"There's a tremendous amount of science that goes into making a successful hot dog, into not having the fat release out of there and having the right bite or texture," Griffin said, "all those things that nobody really gives the hot dog very much credit for."

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Are hot dogs good for you?

Hot dogs may be good, but they aren't necessarily good for you.

Several studies have suggested that a diet loaded with processed meats – such as hot dogs, sausage, cold cuts, and bacon – can be detrimental to your health.

A multinational study published last year in The American Journal of Clinical Nutrition found higher intake of processed meat was associated with higher risks of total mortality and major cardiovascular disease.

Back in 2015, The International Agency for Cancer Research said enough research existed to consider processed meat – such as hot dogs, sausage, cold cuts, and bacon – as a carcinogen that can increase the risk of developing colorectal cancer. Red meat was linked to colorectal, pancreatic and prostate cancer, but the link was not as strong, the cancer research report said.

Hot dogs were also considered the least healthy of 5,800 foods in a study published last year in the peer-reviewed journal Nature Food. The University of Michigan researchers claimed that eating one hot dog can take 36 minutes off of a human's life – in comparison, eating nuts could add 26 minutes.

A hot dog can have 14 grams of fat or more and as much as 500 grams of sodium – almost one-fourth the daily allowance of each.

That doesn't mean you can't or shouldn't eat hot dogs, said Kris Sollid, a registered dietitian and senior director of nutrition communications at the International Food Information Council.

"Are hot dogs the most nutritious thing you can eat? No. But eating a hot dog now and then doesn’t make you or your diet unhealthy," he told USA TODAY. "A healthy eating pattern prioritizes things like fruits, vegetables and whole grains, but can include the occasional hot dog."

But this July Fourth holiday, don't gorge yourself on hot dogs. "I wouldn’t recommend attempting to eat hot dogs in the same quantity that (hot dog eating champ) Joey Chestnut does on the Fourth of July. One or two at a BBQ will probably be enough for most people," Sollid said.

Follow Mike Snider on Twitter: @mikesnider.

This article originally appeared on USA TODAY: What are hot dogs actually made of?