The claim said that packaging and advertisements for mozzarella cheese sticks state the stick are "made with 100 percent real cheese" and "made with real mozzarella."
Howe, the only plaintiff in the suit, said he purchased and ate mozzarella sticks from a Rancho Mirage, California, McDonald's on Dec. 24.
The suit breaks down the labelling of mozzarella and includes Howe's own investigation of the sticks.
According to a diagram in the suit, Howe took a sample from the cores of the sticks by removing both ends of the sticks.
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"Testing the core 'mozzarella' cheese of the sticks reveals that the substance contained within their breading is not mozzarella cheese at all," the suit claims. "It contains non-permitted substances which render it outside the standard of identity of mozzarella cheese."
"The samples taken from within the sticks contain 3.76 percent starch by weight. In other words, the starch becomes a cheap substitute for permitted ingredients, and a vehicle for an even cheaper ingredient: Water."
The suit said that by using cheaper ingredients, it cut production costs, according to CBSLA.
Elga told BuzzFeed News the suit is about transparency. "Our client's case alleges that it is important to keep corporations honest and transparent about the ingredients in their food products, and that adulterated dairy products hurt consumers by short-changing them."
In a statement, McDonald's spokesperson Lisa McComb said, "Our mozzarella cheese sticks are made with 100 percent low-moisture part-skim mozzarella cheese. We intend to defend ourselves vigorously against these allegations."