When it's served in a Taco Bell taco, alleges a California woman in a class-action lawsuit. The suit, filed Friday, claims that the fast-food giant uses so much other ingredients in its meat that it no longer qualifies as beef.

Taco Bell, based in Irvine, Calif., fired back in a statement Tuesday, saying that the suit is "absolutely wrong" and that it planned legal action of its own.

The dispute revolves around how much can be mixed in with beef and still be called beef.

In its raw or frozen form, ground beef "shall not contain more than 30 percent fat, and shall not contain added water, phosphates, binders, or extenders," according to the US Department of Agriculture (USDA). It can include seasonings or not.