You think you’re sprinkling grated Parmesan on your meal, but there might be a hidden — and unappetizing — ingredient in the cheese: wood pulp.

In 2012, the Food and Drug Administration (FDA) raided a grated Parmesan cheese supplier in Pennsylvania and found that a product labeled 100 percent real Parmesan was anything but. It was actually a mixture of Swiss, mozzarella, white cheddar and fillers, including wood pulp, aka cellulose, according to the FDA. Another product labeled Romano cheese contained cheaper cheddar cheese. The FDA issued a warning that put it bluntly: "Your Parmesan cheese products do not contain any Parmesan cheese."

Now the issue of cheese fraud has resurfaced for two reasons. First, the company’s president is expected to plead guilty to criminal charges this month and faces a year in prison and a $100,000 fine. Second, Bloomberg News has revealed the problem is more widespread than anyone may have previously thought. It had different brands of store-bought grated cheese tested for wood pulp by an independent laboratory. Turns out, the mislabeling issue goes far beyond that one Pennsylvania company.

Related: Pulp Fiction (and Fact): The Lowdown on Cellulose in Your Food

Is wood pulp safe to eat?

If you’re eating a diet full of fruits, vegetables and whole grains, you’re already eating cellulose, which is is a building block of plant cells and fiber. Cellulose is also a component of wood fiber, which some food manufacturers use to bulk up food and add texture. An acceptable level in food is 2 percent to 4 percent, Dean Sommer, a cheese technologist at the Center for Dairy Research in Madison, Wisconsin, told Bloomberg News. But Bloomberg’s tests showed some brands contained as much as 8 percent cellulose.

Why would companies do this? The Washington Post reports:

Making Parmesan, Romano and other hard Italian cheeses isn't nearly as efficient as making their softer counterparts — the drying process takes months, shedding moisture and, with it, weight. Depending on how long it sits, the same amount of milk could mean significantly less cheese by weight than it would if a manufacturer were making cheddar, Swiss or mozzarella. Adding a little extra cellulose, or swapping in a little — or a lot — of another cheese, can save commercial manufacturers millions of dollars.

If you want to avoid the possibility of cellulose in your Parmesan cheese, buy a block of Parmesan and shred it yourself.

Manufacturers of Parmesan cheese aren’t the first food makers to come under fire for not disclosing a product’s true ingredients. In 2013, the U.S. International Trade Commission found evidence of olive oil mislabeling. Some brands of oil labeled “extra virgin olive oil” were found to be mixed with additives. (True extra virgin olive oil has no additives.)

Fish is another food that’s often subject to bait-and-switch gimmicks.

The FDA and the U.S. Department of Agriculture are taking steps to prevent food fraud, as are some states. The U.S. Pharmacopeial Convention, a scientific nonprofit organization, has a database of reports of food ingredient fraud.

The spotlight on food fraud may eventually force manufacturers to stop mislabeling their products. In the meantime, as far as phony Parmesan goes, the only risk you face is to your wallet.

Related: FDA to Consumers: What Does the Word “Natural” on Food Labels Mean to You?

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Angela is a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide. Prior to joining SafeBee, she was the features editor for at The Boston Globe, overseeing health, travel, entertainment, business and lifestyle coverage. Before moving to features, she was the news and homepage editor, covering stories such as the Boston Marathon bombing, Red Sox World Series victories, presidential elections, a papal inauguration, and more. Her favorite safety tip: Clean your phone! The average cell phone has 18 times more germs than the toilet handle in a men’s restroom.