A defamation trial over an ABC News report about so-called pink slime, a once-common ingredient in ground beef, is set to begin Monday. A South Dakota meat processing company says the report wreaked havoc on its business after it aired in 2012.

The term refers to low-cost processed beef trimmings sold by Beef Products Inc.

The first use of “pink slime” is widely credited to Gerald Zirnstein, a former Agriculture Department scientist, who used it in a 2002 email to colleagues in which he expressed concerns about the product.

The processed trimmings — officially known as lean finely textured beef — were once a popular ingredient in ground beef and were found in McDonald’s and Burger King hamburgers and in grocery chains and schools across the country.

The product is created by placing trimmings in centrifuges to separate lean meat from fat. The lean meat is then treated with ammonia to remove pathogens. That process, the company has said, was perfected over years and can produce 10 to 20 extra pounds of lean beef per cow.

In 1993, the Agriculture Department approved the processed trimmings for use in ground beef.

Concerns about the product had been mounting for years when, in 2012, ABC News aired an investigation into its widespread use in ground beef.

In the report by the correspondent Jim Avila, Mr. Zirnstein called the trimmings “a cheap substitute” and said that allowing them to be sold as ground beef amounted to an “economic fraud.”

Later that year, Beef Products sued ABC for defamation, arguing that the segment and several…