Oh Nuts!

By Diane Wright Hirsch, MPH

Senior Extension Educator/Food Safety

FDA nutsEggs, chicken, lettuce, sprouts, and now pistachios. Some readers may think that this association of pistachios with a Salmonellosis outbreak is unusual if not rare. Well, though not likely to be defined as “common,” in recent years a number of outbreaks have been traced to nuts and nut products.

Currently, there is an ongoing outbreak associated with pistachios, with the US Food and Drug Administration (FDA) issuing a recall notice on March 10. The brand of the pistachios was the Wonderful brand, but these were also distributed under the Paramount Farms and Trader Joe’s brands, and others. A list of all lot numbers that have been recalled can be found on the FDA web site (www.fda.gov). At this point, eleven people from nine states have been identified as infected with the outbreak strain of Salmonella Montevideo, including one person in Connecticut. Two ill people have been hospitalized. No deaths have been reported. Because the shelf life for these products is long, some may still be on consumer shelves, so be sure to check your pantry for the recalled lot numbers.

Salmonella is a foodborne illness causing bacteria that is estimated to cause more than one million foodborne illnesses in the United States, with 19,000 hospitalizations and 450 deaths. Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection. The illness usually lasts four to seven days, and most persons recover without treatment. However, in some persons, particularly those with compromised immune systems, the elderly and the very young, the diarrhea may be so severe that the patient needs to be hospitalized.

There are a many strains or serotypes of the bacteria: S. Montevideo has caused this outbreak. You may be more familiar with S. Enteriditis. Some strains may be more virulent than others, causing more severe symptoms and side effects.

But why pistachios?

Historically, it was thought that nuts were likely too low in moisture to support the growth of foodborne illness causing bacteria. However, researchers have shown now that Salmonella can live on dry products and in peanut butter for as long as six months.

There have been 11 outbreaks from nuts and nut products (butters, spreads, “cheese”) since 2010, affecting 169 people. There were 25 recalls of contaminated nut products just in 2015. Recalls are often conducted as a result of a testing program—while a foodborne pathogen may show up during testing, it may not result in widespread illness.

And of course, there was the Peanut Corporation of America’s outbreak that resulted in the recall of more than 3,900 products from more than 200 companies, all containing peanut butter or peanut paste from PCA. This outbreak was due to a company that was negligent in its sanitation programs and knowingly shipped contaminated products: four people have been sentenced to prison terms in this case, including the owners of the company, the Parnell brothers.

But most cases are not the result of gross mismanagement and fraud. Nuts like any other product grown in orchards and fields can be contaminated by bird poop or irrigation water or during harvest, especially if the nuts come into contact with the ground. This is one reason, after several outbreaks traced back to almonds, in 2007, the USDA Agricultural Marketing Service (AMS) passed a rule that requires all handlers of almonds to use a process, such as pasteurization, that will significantly reduce the presence of Salmonella.

In addition, during processing, nuts may be soaked in water to soften shells—if the shells are contaminated, this process could spread the bacteria. And, like any other processed food, a good sanitation program is essential. Otherwise a processor runs the risk of cross-contaminating clean product with dirty surfaces or utensils. Or, Listeria can take up residence in the processing environment, risking the contamination of nuts after they are cooked, roasted, or pasteurized.

So, is this something to be concerned about? Well the good news is no, you do not need to be stressed out over your favorite peanut butter. However, if you or a family member is elderly, very young or has an immune system compromised by chronic illness, medications or other condition, then maybe you should steer clear of raw nuts or raw nut butters.

The FDA is presently considering conducting a risk assessment for salmonella in tree nuts (almonds, cashews, macadamia nuts, pistachios, walnuts, etc.) as a result of increasing numbers of recalls and outbreaks. The results of this risk assessment may lead to additional regulations, rules, or guidance documents focused on the nut industry.

Recently, the Food Safety Modernization Act (FSMA) rules were finalized. This, too, will increase jurisdiction of the FDA over both growers and processors of nuts and nut products. The Produce Safety Rule will address what goes on in the field; the Prevention and Controls Rule will impact processing operations. Attention is drawn to safer irrigation methods, worker health and hygiene (important during harvest), sanitation in the field and in the packinghouse. Regular inspections of farms and processing plants will be part of the new regulations.

If you grow nut trees at home, keep these points in mind:

  • Minimize contact with ground during harvest. Consider covering the ground with a CLEAN tarp or sheet to catch the nuts.
  • Handle harvested nuts with clean hands.
  • Always wash surfaces that come into contact with harvested nuts—counters, table tops, etc.
  • When opening raw nuts, be sure to use clean hands and utensils.
  • Dry/cure nuts completely before storage—again using clean equipment.
  • Store nuts in a clean container. Freezing or refrigerating will further reduce the risk of bacterial growth.

For more information on growing and the safe handling of nuts, contact the Home and Garden Education Center at ladybug@uconn.edu or 1-877-486-6271.