- Many civilizations have relied on nuts as part of their diet, even before the usage of cereal grains. Nuts come from a variety of botanical families and serve as a reliable and timely food source because they are resistant to damage by severe weather, are easily preserved through long winters to ensure a stable food supply, and provide essential fatty acids, protein, and important micronutrients.
- Nut butters have been associated with Salmonella outbreaks, especially Salmonella Bredeney and Typhimurium; a very large outbreak in 2010 was associated with peanut paste used in a wide variety of food products.
- The US is the world’s third largest peanut producer, following China and India. The state of Georgia has the largest peanut production in the US, followed by Texas.
- Research studies have linked nut consumption with reduced heart disease and gallstones in both genders and diabetes in women. There is also evidence pointing towards easing hypertension, cancer, and inflammation
The term ‘nut butter’ is a generic name for any spreadable food product made from crushed or blended nuts. The six most common nuts used in making nut butter are almond (Prunus dulcis) from the Rosaceae plant family, cashew (Anacardium occidentale) from the Anacardiaceae family, hazelnut (Corylus avellana) from Betulaceae family, peanut (Arachis hypogaea) and soybean (Glycine max), both from the Fabaceae family . Peanut production is primarily focused in three major geographic areas of the United States: the Southeast (Alabama, Florida, Georgia, Mississippi, South Carolina), the Southwest (New Mexico, Oklahoma, Texas) and Virginia and North Carolina . The United States is the leading producer of almonds, accounting for 68% of the world’s almond production. They are mainly grown in central California . Ninety-nine 99% of hazelnut production is found in Oregon. From 2007 to 2011, hazelnut production has fluctuated but has steadily climbed to over 40,000 tons . In recent years, nut consumption in the U.S. has averaged 3.3 pounds per person, which is greater than past intake, potentially due to increased output of tree nuts . The large influx of imported tree nuts, such as cashews, accounted for 33% of all tree nut consumption from 2007 to 2008 .
Salmonella had been associated with the following nut butter outbreaks:
2014: In August of 2014, almond and peanut butters, packaged in glass and plastic jars under various brand labels, were recalled because of potential contamination with Salmonella. Since nut butter products have a long shelf life there is always concern regarding consumers who were not aware of a recall and could still have these products in their homes .
CDC reported a total of six persons were infected with the outbreak strain of Salmonella Braenderup since January 1, 2014: One in Connecticut, one in Iowa, one in New Mexico, one in Tennessee, and one in Texas. While one ill person was hospitalized, no deaths were reported .
2012: CDC collaborated with public health officials in several states and the U.S. Food and Drug Administration (FDA) to investigate a multi-state outbreak of Salmonella Bredeney infections from Trader Joe’s Valencia Peanut Butter, manufactured by Sunland, Inc. of Portales, New Mexico. DNA ‘fingerprints’ of Salmonella bacteria from Pulse-Net, the national sub-typing network that performs molecular surveillance of foodborne infections, were used through diagnostic testing with pulsed-field gel electrophoresis (PFGE) to identify the bacteria that were part of this outbreak .
According to the CDC, a total of 42 people were infected with the outbreak strain of Salmonella Bredeney from 20 states, 68% were children under the age of 10 years, 59% were male; 28% were hospitalized, and no deaths were reported .
2007: Public health officials in multiple states, CDC, and FDA investigated a large multi-state outbreak of Salmonella Tennessee (serotype) infections. An epidemiological study was executed comparing ill and well persons that ate Peter Pan peanut butter and Great Value peanut butter and it was concluded that both products were likely the source of the outbreak. Product testing confirmed the presence of the outbreak strain of Salmonella Tennessee in opened jars of peanut butter obtained from ill persons. Consumers were alerted not to consume peanut butter with a product code beginning with 2111. CDC reported 425 persons infected with the outbreak strain of Salmonella Tennessee in 44 states. From 351 patients for whom clinical information is available, 71 (20%) were hospitalized. No deaths were attributed to this infection .
2004: An outbreak of Salmonella Enteritidis occurred in 12 US states and in Canada from Paramount and Raw Almonds.
Production – Peanut Butter
The origin of peanuts dates back to around 950 BC in South America. They were brought to Africa by early explorers, then transported to North America in the colonial age. Peanuts were first used as animal feed and human consumption began only in the late 19th century. In 2012, the average American consumed approximately 6.7 lbs of peanuts a year, more than half in the form of peanut butter .
The U.S. production of peanuts is approximately 6.8 billion lbs . Georgia is the number one producer of peanuts, comprising almost half of U.S. production and value. In total, over one million acres of peanuts are planted and harvested in the U.S. each year. Approximately 60% of total production is dedicated for human consumption and the remaining is used for seed, animal feed, and oil. Over 60% of peanuts used for human consumption are processed into peanut butter .
Peanut butter is processed similar to peanuts, up to the roasting state it is the same way, until the time that peanuts are finely grounded into a paste and vacuum packaged.
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One of the biggest concerns with nut butters, especially with peanut butter, is contamination with Salmonella because of this pathogen’s ability to survive in peanut butter, despite the low water activity (aw). Researchers have found an initial inoculum of 5.68 log colony-forming units per gram (CFU/g) of peanut butter can result in greater than 3 log CFU/g after 1 week at 5 °C and 21 °C. Even after 24 weeks, approximately 2 and 1 log CFU/g Salmonella was detected at 5 °C and 21 °C, respectively. A 3-strain cocktail of Salmonella Tennessee inoculated in peanut butter survived for 2 weeks at 4 and 22 °C. Another pathogen, Listeria monocytogenes, was able to survive for 24 weeks in peanut butter at 20 °C with an initial inoculation level of 4 log CFU/g. Studies such as these suggest that pathogen contamination of peanut butter after heat processing could remain in the product throughout its shelf life . Potential contamination by L. monocytogenes prompted nationwide recalls of certain brands of peanut butter (2010) and peanut butter & jelly sandwiches (2011).
Better control technologies have been developed in response to outbreaks associated with peanuts. Adaptation of new processing techniques such as electron beam radiation to control pathogens in peanut butter has been studied. For example, a study examining high-pressure processing (HPP; 600 MPa for 5 min at 45 °C) against inoculated Salmonella in peanut butter found <2 log unit reductions. However, thermal treatment of peanut butter is not always effective since Salmonella has been shown to survive in peanut butter heated to 90 °C. This may be feasible due to the high fat content acting as a local buffer which allows Salmonella to survive with increased heat resistance. This finding suggests that peanut butter and other high fat and low aw foods cannot simply be heated to destroy all potential Salmonella pathogens. Furthermore, by utilizing the heat process too often, this may instead induce new stress responses in bacteria to adapt and thrive .
In conclusion, perhaps the use of sanitary water, sanitary facilities, personal hygiene, plant sanitation, proper transportation, and other prevention-based food safety programs can help prevent any initial contamination to the product.
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Nuts contain 70-80% fat, mostly unsaturated fatty acids (monounsaturated and polyunsaturated) which may be beneficial for glucose and insulin homeostasis . An ounce of plain nuts, without salt or sugar, contains between 160 to 200 calories and about 13 to 20 grams of fat. However, nuts are naturally cholesterol free and low in saturated fat with only 1-2.5 grams per ounce. Nuts also supply important vitamins, such as vitamin E, folic acid, vitamin B-6, and niacin, and minerals, such as magnesium, zinc, copper, and potassium .