ConAgra Foods’ subsidiary, ConAgra Grocery Products, has agreed to plead guilty and pay a fine of $11.2m regarding the shipment of contaminated peanut butter linked to a nationwide outbreak of salmonella poisoning from 2006-2007, the US Department of Justice announced.

Said to be the largest ever criminal fine paid in a food safety case, ConAgra will pay a fine of $8m and forfeit assets of $3.2m.

In February 2007, the US Food and Drug Administration (FDA), and the Centers for Disease Control and Prevention (CDC) had linked the salmonellosis outbreak to Peter Pan and private label peanut butter that had been produced and shipped from ConAgra’s Sylvester peanut butter plant.

"The safety of the nation’s food supply is a top concern, and every company, large and small, must take appropriate measures to ensure that their products don’t make customers sick."

On 14 February 2007, the company voluntarily stopped production at the plant and recalled all peanut butter produced since January 2004.

Eventually, more than 700 cases of salmonellosis linked to the outbreak with illness onset dates beginning in August 2006 were identified by CDC. The centre could not find any deaths due to the outbreak.

The company later said that peanut butter which was produced on nine different dates between 4 August 2006 and 29 January 2007 was contaminated with salmonella. It identified several potential contributing factors, including an old peanut roaster that was not uniformly heating raw peanuts, a storm-damaged sugar silo, a leaky roof that allowed moisture into the plant, and airflow that could allow potential contaminants to move around the plant.

Later tests found the salmonella strain at around nine locations at the plant.

Principal deputy assistant Attorney General Mizer said: "The safety of the nation’s food supply is a top concern, and every company, large and small, must take appropriate measures to ensure that their products don’t make customers sick.

"No company can let down its guard when it comes to these kinds of microbiological contaminants. Salmonellosis is a serious condition, and a food like peanut butter can deliver it straight to children and other vulnerable populations."