How Does Peanut Butter Get Salmonella?

Peanut butter can be contaminated with Salmonella from manure, water, wild animals, and soil when peanuts are grown. Sometimes contamination happens in the processing plant after roasting the peanuts, which may get exposed to water with the bacteria (such as through a roof leak at the processing plant).

Salmonella is a bacterial infection that often causes food poisoning because it affects the digestive tract. Salmonella infection (called salmonellosis) is usually not serious, and most people recover within a week. 

Salmonellosis is caused by infection with Salmonella bacteria. People usually become infected after eating food (or touching an animal) contaminated with the Salmonella bacteria. 

We sometimes hear of product recalls of peanut butter contaminated with Salmonella, but how does Salmonella get into the peanut butter? 

Peanuts are grown in the ground and may become contaminated with Salmonella bacteria from several sources: 

• Manure
• Water
• Wild animals
• Soil

When peanuts are harvested, there is often Salmonella present, and the bacteria can survive for a long time in peanut butter. Fatty foods are protective of Salmonella, and peanut butter, a highly fatty food, allows the bacteria to survive better. However, peanut butter products are routinely treated to kill the bacteria. A roaster with air temperatures set to about 300oF is used to destroy Salmonella in peanuts, called the “kill step” by manufacturers. 

However, even after this step used to kill the Salmonella bacteria, contamination may occur in the processing plant after the roasting. The problem is often due to water entering into the process. For example, a roof leak in a processing plant caused one Salmonella outbreak.

13 Other Sources of Salmonella

In addition to peanut butter, other foods that may commonly have Salmonella bacteria include: 

• Eggs
• Beef
• Pork
• Chicken 
• Turkey
• Raw and undercooked meat
• Dairy products
• Sprouts
• Raw fruits or vegetables
• Processed foods
  • Other types of nut butter
  • Chicken nuggets
  • Frozen pot pies
  • Stuffed chicken entrees

People can also get salmonellosis from touching certain animals, including:

• Chickens
• Turtles
• Ducks