There may be a secret ingredient in your Parmesan cheese: wood.

A recent Bloomberg News investigation has found that certain cheeses have more of it than they probably should.

The additive is apparently used to prevent clumping, something that can also be avoided with potato starch, according to food scientist Mark Johnson of the Center for Dairy Research in Wisconsin.

Wood pulp is actually considered safe for consumption in certain quantities, he claims. An acceptable level is believed to be between two to three per cent, he estimates — even though “we don’t have the ability to digest the wood.”

Johnson has heard of some U.S. cheese manufacturers using wood pulp — its technical name is “cellulose” — for as long as he’s been in the industry (since 1980).

However, “there may be a temptation to [use] more than necessary.” Johnson says that’s because wood pulp is cheaper than cheese, so some companies may use more to undercut their competition.

Bloomberg’s lab tests revealed: “Wal-Mart Stores Inc.’s Great Value 100% Grated Parmesan Cheese registered 7.8 per cent [cellulose]… Whole Foods 365 brand didn’t list cellulose as an ingredient on the label, but still tested at 0.3 percent. Kraft had 3.8 per cent.”

Whole Foods told Bloomberg it is looking into the matter, and added that the cellulose identified in its product could’ve been a false positive.

Aside from grated Parmesan, Johnson believes wood pulp is also used in cheese slices every now and then. He adds it’s not as common in shredded cheese, where it would be easier to see.

“It’d be a detriment to the visual quality.”

The Blooomberg report also recounted how the addition of wood pulp landed the president of a Pennsylvania-based cheese factory Castle Cheese Inc. before the courts.

Michelle Myrter’s company allegedly claimed to sell 100 per cent grated Parmesan, which an FDA investigation found to be false. “You declare Parmesan cheese as an ingredient; however, you do not use Parmesan cheese to manufacture your product,” stated a letter dated July 11, 2013.

“A substance has been added to increase the products’ bulk and weight. Specifically, cellulose and/or starch were used to increase the weight of the cheese base used to manufacture your products,” the FDA warned.

The company filed for bankruptcy the following year. Myrter is expected to plead guilty this month to criminal charges, for which she could serve up to a year in prison and be fined $100,000.

“The industry wants to be known for a wholesome, safe, honest product — it’s what’s kept the industry growing for 100 years,” John Umhoefer, executive director of the Wisconsin Cheese Makers Association told Bloomberg News.

The FDA has regulated what can legally be called Parmesan cheese for over 60 years, to ensure a consistent standard among manufacturers.

Canada imports over $10 million worth of grated or powdered Parmesan cheese products annually, based on data from Statistics Canada.

Global News reached out to the Canadian Food Inspection Agency to find out whether grated Parmesan cheese sold here could contain the wood additive. The agency was not able to answer our questions by time of publishing.

We also contacted Kraft Canada and Walmart Canada but, as of yet, have not received a response.

If the idea of potentially sprinkling your pasta with wood shavings doesn’t appeal to you, just do what Johnson does.