Salmonella and Army use of low-moisture foods

Non-typhoidal Salmonella is a foodborne pathogen that has one of the highest incidences of hospitalizations and deaths. The foodborne illness symptoms can include fever, abdominal pain, diarrhea, nausea and vomiting. The high incidence of foodborne illness coupled with a large number of outbreaks in commercial low moisture foods LMF such as peanut butter prompted Army researchers to investigate S. enterica survivability in LMF rations.

The majority of LMF are not cooked prior to consumption so contamination at the time of manufacture could lead to illness when consumed by the soldier. In addition, military rations are prepositioned and can be stored for up to 3 years at various climate conditions therefore, this study evaluated various storage temperatures to simulate conditions in the field. LMF products in this study were chosen based on categories outlined by Institute of Food Safety and Health peanut butter, mocha desert bar, dehydrated egg, chocolate protein drink and cran-raspberry first strike bar.

Previous studies identified potential synergistic effect on S. enterica survival in high fat, low water activity foods such as peanut butter. This experiment expanded on these predictions and evaluated foods with varying compositions which undergo unique storage requirements prior to consumption.

Survival of salmonella enterica in low moisture military ration products

Army Natick Soldier Research Development and Engineering Center

Flock,Genevieve,  Richardson,MichellePacitto,DominiqueCowell,CourtneyAnderson,NateMarek,PatrickSenecal,Andy

03 June 2020

I love it when Chapman talks about low-moisture foods

A number of recent outbreaks related to pathogens in low-moisture foods have created urgency for studies to understand the possible causes and identify potential treatments to improve low-moisture food safety.

ben_chapman2Thermal processing holds the potential to eliminate pathogens such as Salmonella in low-moisture foods. Water activity (aw) has been recognized as one of the primary factors influencing the thermal resistance of pathogens in low-moisture foods. But most of the reported studies relate thermal resistance of pathogens to aw of low-moisture foods at room temperature. Water activity is a thermodynamic property that varies significantly with temperature and the direction of variation is dependent on the product component.

Accurate methods to determine aw at elevated temperatures are needed in related research activities and industrial operations. Adequate design of commercial thermal treatments to control target pathogens in low-moisture products requires knowledge on how aw values change in different foods at elevated temperatures.

This paper presents an overview of the factors influencing the thermal resistance of pathogens in low-moisture foods. This review focuses on understanding the influence of water activity and its variation at thermal processing temperature on thermal resistance of pathogens in different low-moisture matrices. It also discusses the research needs to relate thermal resistance of foodborne pathogens to aw value in those foods at elevated temperatures.


Influence of water activity on thermal resistance of microorganisms in low-moisture foods: A review

Comprehensive Reviews in Food Science and Food Safety

Roopesh M. Syamaladevi, Juming Tang, Rossana Villa-Rojas, Shyam Sablani, Brady Carter, and Gaylon Campbell


Recall creep demonstrates system issues

When folks try to limit recall size and scope without good traceability and sanitation clean breaks they usually aren’t successful. One recall announcement turns quickly into multiple and leads to larger questions about overall systems.

Last year, during the Blue Bell’s outbreak response and recall Marler and I both highlighted the issue of recall creep:

“Maybe the cleaning and sanitation program that Blue Bell was using wasn’t adequate. As more samples came back … it highlights that this problem was larger than they originally thought.”

“Limiting the recall might seem like a good idea. But then if you keep expanding your recall, it’s a death by a thousand cuts. You look like you’re dragging your feet.”

Traceability, sanitation, product lots, suppliers, ingredients. All this stuff, if not managed well, especially as investigators start asking for documentation, leads to recall expansion.

Here’s today’s recall creep example, care of Texas Star Nut & Food Company:

Screen Shot 2016-03-15 at 11.59.34 AM

The above listed products, were distributed to Retailers nationwide. These products were sold between 8/13/2015 and 2/24/2016.

The company has ceased the distribution of all of the above products containing pistachio kernels. The recall was as a result of a routine, random sampling program conducted by a FDA third party contracted lab which revealed that the Nature’s Eats Natural Pistachio Kernels product contained Salmonella.

Consumers who have purchased any of the above listed products and best by dates are urged to discontinue consuming the potentially affected product and may return product to the retail location for a refund. Consumers with concerns or questions should contact the company at 1-844-571-5555 from 8:30am to 5:30 pm Central Standard Time.

From the Salmonella-in-low-moisture-foods file: survival for 180+ days in cookie and cracker sandwiches

In 2009 when PCA was distributing Salmonella-contaminated peanut paste products to lots of manufacturers, many were asking questions about how the pathogen survived in the low-moisture environment and whether the outbreak was an indicator that the snack food industry was facing a larger issue. Since then there have been numerous low-moisture food outbreaks (here’s a nice review from Sofia Santillana Farakos and Joe Franks).

Friends of barfblog Larry Beuchat (right, exactly as shown) and Scott Burnett did some work on peanut butter and Salmonella and showed that the pathogen could survive for a long, long time, Larry-Beuchat-28622-105-230x154‘Post-process contamination of peanut butter and spreads with Salmonella may to result in survival in these products for the duration of their shelf life at 5 degrees C and possibly 21 degrees C, depending on the formulation.’

Larry has published another great paper on Salmonella in low moisture foods, Survival of Salmonella in Cookie and Cracker Sandwiches Containing Inoculated, Low-Water Activity Fillings in JFP. From the abstract, ‘The ability of Salmonella to survive for at least 182 days in fillings of cookie and cracker sandwiches demonstrates a need to assure that filling ingredients do not contain the pathogen and that contamination does not occur during manufacture.’


Or in his own words,

“There have been an increased number of outbreaks of diseases associated with consumption of contaminated dry foods. We wouldn’t expect salmonella to grow in foods that have a very dry environment,” said Beuchat, who works with the Center for Food Safety on the UGA campus in Griffin.

Focusing on cookie and cracker sandwiches, the researchers put the salmonella into four types of fillings found in cookies or crackers and placed them into storage. The researchers used cheese and peanut butter fillings for the cracker sandwiches and chocolate and vanilla fillings for the cookie sandwiches.

These “are the kind that we find in grocery stores or vending machines,” Beuchat said.

“The salmonella didn’t survive as well in the cracker sandwiches as it did in the cookie sandwiches,” Beuchat said.

In some cases, the pathogen was able to survive for at least to six months in the sandwiches.“That was not expected,” he said.

Willy Wonka would be proud: Microbiological Safety of Low Water Activity Foods and Spices

Chapman has written about his obsession with low moisture foods and how he terrifies his children about Salmonella in chocolate.

Now he has a month worth of bedtime reading: The Microbiological Safety of Low Water Activity Foods and Spices

Gurtler, Joshua B., Doyle, Michael P., Kornacki, Jeffrey L. (Eds.)

willy-wonka-and-the-chocolate-factory-willy-wonka-and-the-chocolate-factory-17594222-640-480Describes the microbial challenges to ensuring the safety of low water activity (aw) food

Gives insight into regulatory issues, and appropriate product sampling and testing methods

Explores the efficacy of industrially-used and potential product decontamination interventions

Low water activity (aw) and dried foods such as dried dairy and meat products, grain-based and dried ready-to-eat cereal products, powdered infant formula, peanut and nut pastes, as well as flours and meals have increasingly been associated with product recalls and foodborne outbreaks due to contamination by pathogens such as Salmonella spp. and enterohemorrhagic E. coli. 

In particular, recent foodborne outbreaks and product recalls related to Salmonella-contaminated spices have raised the level of public health concern for spices as agents of foodborne illnesses.

Presently, most spices are grown outside the U.S., mainly in 8 countries: India, Indonesia, China, Brazil, Peru, Madagascar, Mexico and Vietnam. Many of these countries are under-developed and spices are harvested and stored with little heed to sanitation. The USDA has regulatory oversight of spices in the United States; however, the agency’s control is largely limited to enforcing regulatory compliance through sampling and testing only after imported foodstuffs have crossed the U.S. border. Unfortunately, statistical sampling plans are inefficient tools for ensuring total food safety. As a result, the development and use of decontamination treatments is key. 

Willy_Wonka_by_lovelookalikeThis book provides an understanding of the microbial challenges to the safety of low aw foods, and a historic backdrop to the paradigm shift now highlighting low aw foods as vehicles for foodborne pathogens.  Up-to-date facts and figures of foodborne illness outbreaks and product recalls are included.  Special attention is given to the uncanny ability of Salmonella to persist under dry conditions in food processing plants and foods.  A section is dedicated specifically to processing plant investigations, providing practical approaches to determining sources of persistent bacterial strains in the industrial food processing environment.  Readers are guided through dry cleaning, wet cleaning and alternatives to processing plant hygiene and sanitation.  Separate chapters are devoted to low aw food commodities of interest including spices, dried dairy-based products, low aw meat products, dried ready-to-eat cereal products, powdered infant formula, nuts and nut pastes, flours and meals, chocolate and confectionary, dried teas and herbs, and pet foods. 

The book provides regulatory testing guidelines and recommendations as well as guidance through methodological and sampling challenges to testing spices and low aw foods for the presence of foodborne pathogens.  Chapters also address decontamination processes for low aw foods, including heat, steam, irradiation, microwave, and alternative energy-based treatments.

From the Salmonella in low moisture foods file: Aldi recalls Choceur Treasures chocolate

Last weekend I taught Jack and Sam about Salmonella contamination in low moisture foods like chocolate – through the somewhat creepy Charlie and the Chocolate Factory. Early on in the golden ticket winners visit, Augustus Gloop (which is also a decent band name) falls into the factory’s open chocolate river. Knowing that Salmonella is hearty, especially when stressed in a low moisture environment, and that the chocolate didn’t have a post-river kill step, Wonka yells ‘ You are dirtying my chocolate!’.10881542_733085970120889_7656214917050489571_n

In related news, a UK retailer, Aldi, is according to The Telegraph, recalling chocolate due to Salmonella contamination.

Aldi, the discount supermarket, is recalling packs of chocolate after salmonella was detected in a batch. The Food Standards Agency has issued a product recall notice for 200g Choceur Treasures with a best before date of Sept 1. The bacteria was found in a batch of the product that has been on sale in Aldi stores in the Midlands region. The chocolates – a whole hazelnut wrapped in waffle and milk chocolate – at the centre of the scare have been on sale in around 100 stores. Locations if shops include Birmingham, Worcester, Leicester, Derby, Nottingham, Wolverhampton, Coventry and Grantham.

Maybe someone fell into their chocolate river.