Salmonella in Peanut Butter: Why Does It Keep Happening?
The United States produces about 3 million tons of peanuts each year, with each peanut farm averaging about 200 acres. A significant share of the peanuts grown in the US is turned into peanut butter, one of the nation's most popular foods. According to Statista, more than 299 million Americans consume peanut butter, with sales reaching more than $2 billion annually. In recent years, this much-loved food has been plagued by peanut butter recalls due to Salmonella concerns.
Salmonella is a type of bacteria that can make people very sick, with most individuals experiencing diarrhea, cramps, and fever. Each year about 1.35 million people become ill due to Salmonella, according to estimates Centers for Disease Control and Prevention (CDC). While most people recover from Salmonella infection (called salmonellosis) without issue, people with certain health conditions or compromised immune systems can experience severe symptoms, potentially resulting in hospitalization or death.
Peanut Butter Recalls: A Recurring Problem
In May 2022, the CDC reported a worldwide recall for peanut butter and products containing peanut butter due to the presence of Salmonella bacteria. This outbreak occurred at one production facility, yet over 20 other companies had to recall products because they were made with the recalled peanut butter. This recall included not only products for human consumption but also pet food and treats. The company responsible for the Salmonella outbreak has reported losses of approximately $125 million.
A similar outbreak in 2008 and 2009 led to the recall of more than 3,900 products from over 200 companies. Over 700 people became ill during this outbreak, with over 100 hospitalizations and nine deaths (Grasso, et al., 2010).
Why Is Peanut Butter Being Contaminated by Salmonella?
Many consumers may wonder what causes Salmonella in peanut butter since most people associate Salmonella with poultry, raw eggs, and raw flour. All types of bacteria, including Salmonella, usually need specific conditions to grow and thrive. Bacteria need food, acidity, time, temperature control, oxygen, and moisture (FAT TOM).
- Bacteria need food to grow and thrive. High protein and carbohydrate foods, such as eggs, pasta, and potatoes, are easily contaminated foods.
- Pathogens like Salmonella grow best in low-acid foods.
- Time and temperature. Pathogens and bacteria need time to grow and multiply. Foods and ingredients left in the temperature zone of 40-140F can help bacteria spread and form spore-producing colonies which cannot be cooked off in high heat.
- Most pathogens need oxygen to survive.
- Bacteria need moisture to grow and thrive.
Peanut butter is a shelf-stable food, meaning it doesn't require refrigeration or cooking to be enjoyed. Its fatty acid profile typically contains higher amounts of oleic acid than linoleic acids, which increases its shelf life. However, products containing a greater amount of linoleic acid are more likely to go rancid more quickly (Gong, et al., 2018).
Peanut butter is also high in fat and low in moisture, around 5%. It is also a low water activity food, meaning water is not added, removed, or naturally occurring in high volumes. This means it is unlikely to be able to sustain vegetative pathogens, like Salmonella (Podolak, et. al., 2010).
While low moisture foods have an environment in which pathogens can't grow well or thrive, they can survive for a long time, as is the case with Salmonella in peanut butter. The high-fat content of peanut butter may help the Salmonella bacteria survive (Burtett, et al., 2001). This can be problematic, especially if contamination occurs a key safety point in the manufacturing process, such as high temperature roasting. If contamination occurs from poor hygiene practices after high temperature roasting, most pathogens will die off but some may survive for many weeks.
Peanut butter and peanuts aren't high-risk foods on their own, as they don't often come in contact with the Salmonella pathogen. However, contamination can occur during the manufacturing process. Peanuts are grown underground. When the peanuts are ready for processing, they are dug up, roasted at high heat, and have their outer shell removed. This high-heat roasting is able to kill off any pathogens that may have been introduced on the exterior shell of the peanut. After roasting, peanuts are then ground into nut butter and jarred.
However, in between those basic three steps is where contamination can occur. In some facilities, after the peanuts are roasted and shelled, they may sit in large piles or in large containers. Exposure to rainwater, moisture, and feces from birds or rodents are all potential Salmonella contamination sources. Additionally, equipment may become contaminated if processors do not adhere to proper sanitation protocols. The hardiness, or ability to maintain heat resistance, depends on many factors such as the strain of Salmonella, growth and storage conditions of the peanuts and nut butter, level of contamination, hygiene of manufacturing equipment, and testing protocols (Podolak, et al., 2010).
If peanuts come in contact with a pathogen after roasting, the Salmonella can survive, often for many months. Once alive in a jar of peanut butter, some Salmonella bacteria have been found to survive up to 24 weeks (Burtett, et al., 2001).
How You Can Reduce the Risk of Salmonella
Mitigating the risks of bacteria and other pathogens is essential for every food producer and processor. Peanut butter recalls due to Salmonella have been costly to the growers, producers, and consumers. Salmonella in peanut butter, and most foods, is preventable when proper food safety precautions are taken. Work with your team to create a Hazard Analysis Critical Control Point (HACCP) plan, identify potential contamination points, and create solutions to minimize production risks.
The Eurofins network of laboratories has specialized expertise and analytical methods to help test your peanut butter products and ensure their safety. Testing for foodborne illness pathogens like Salmonella can protect your brand image and prevent costly remediation while protecting consumers from unwanted health consequences.
