Plastic or corrugated containers? Which is better for produce food safety

Two recent studies of bacteria on reusable plastic containers — both sponsored by corrugated carton groups — question the cleaning process used on RPCs before they enter the supply chain again.

reusable-plastic-containerRPC supplier IFCO and the Reusable Packaging Association has countered that no foodborne illness outbreak has been traced to RPCS.

Keith Warriner, professor of food safety at the University of Guelph in Ontario, Canada, said the study of RPCs — commissioned by the Canadian Corrugated and Containerboard Association — was an extension of one he performed in 2013. The first study tested 50 RPCs, the 2014 study involved 160 RPCs.

In the 2014 study, RPC samples from five Canadian packing facilities were pulled from different lots of trays that had been delivered on pallets wrapped with plastic film. Corrugated cartons from those facilities were not tested for comparison, Warriner said.

The study found that 13% of the RPCs tested positive for generic E. coli, but none tested positive for salmonella; 73% exceeded bacterial load levels, although that doesn’t mean they tested positive for E. coli, salmonella, listeria or other pathogens commonly associated with foodborne illness outbreaks.

“The results of the study have confirmed that a high proportion of RPCs are of poor sanitary status due to inadequate sanitation or post-cleaning contamination,” Warriner said in the study’s conclusion.

Trevor Suslow, produce safety specialist and plant pathologist at University of California-Davis, also conducted a recent study of RPCs, “Assessment of General RPC Cleanliness As Delivered for Use in Packing and Distribution of Fresh Produce.” Corrugated Delivers sponsored efforts to publicize the results and International Paper sponsored the testing.

Suslow said his research shows inconsistencies in the system for handling pooled RPCs. The difference between the Canadian study and Suslow’s is that his research tested RPCs with visible organic matter or residual produce material.

“The main takeaway from that is that we found, other than in a few cases across a few different weeks or pallet loads, the units that looked visually clean and dry had very similar viable or living microbial indicator counts compared to the ones we pulled apart for cause,” he said.

Spray-on DNA bar codes could detect pathogens on produce

Stephanie Lee of the San Francisco Chronicle, writes that to prevent and contain outbreaks of food-borne illness, which sicken 1 in 6

spray.on.dna.produceAmericans annually, a Bay Area startup is developing bar codes that go directly on fruits and vegetables. But you may overlook them: they’re DNA-size.

Using technology invented at Lawrence Livermore National Laboratory, DNATrek is creating liquids that each contain a unique DNA sequence. The odorless, colorless and tasteless solution peppers the surface of produce, or blends into other oils and liquids, with a genetic bar code that can be identified by a special machine.

The technology could solve the enormous challenge of tracing an outbreak’s source — the places where food items are grown, packed and shipped. When people start feeling the symptoms of salmonella or E. coli, many clues about the contaminated product’s origins, such as the shipment boxes, already have disappeared.

The Food and Drug Administration has already recognized the invention as a safe food additive, but for now, the industry does not use it. After large-scale tests that are set to begin next year, DNATrek believes that its tool will emerge as a powerful weapon against food-borne illnesses, which cost the country an estimated $150 billion a year in health-related expenses, and counterfeit food products, which cost the global industry $10 billion to $15 billion annually.

DNATrek suggests that its bar codes may have come in handy in 2012, when an E. coli outbreak caused by contaminated spinach led 13 people to be hospitalized, and in 2011, when 33 Americans died after eating tainted cantaloupe. “If there’s a problem at home and there’s a piece of the cantaloupe left, you can pick it out of the trash, you can scrub the surface, and all the available information is there and you know exactly where it came from,” said Anthony Zografos, founder and CEO of the self-funded, three-employee startup that expects to close a round of seed funding by the end of the month.

Safety concerns

George Farquar, a physical chemist at Lawrence Livermore, patented the product in 2010 with about $3 million in research funding from the Department of Defense. Originally conceived as a biodefense tool, it combines FDA-approved foodstuffs, such as sugar, and a unique DNA sequence to create safe, inhalable microparticles for the purposes of tracking airflow indoors and outdoors. It has been used to test whether, for instance, air detection systems are able to notice particles that resemble anthrax. Last week, company executives and scientists traveled to the Pentagon to run their third series of tests.

Farm to table: Preventing foodborne outbreaks

Monitoring pathogens for their infectious capacity in humans may not be the best approach to minimize the risk of foodborne outbreaks, say researchers who spoke during the 2014 ASM General Meeting in Boston last May.

lettuce.tomato.skullOther factors come into play—particularly, the ability of some pathogens to colonize food sources, proliferate, and thus amplify the inoculating dose delivered to consumers is critically important, they say. Colonizing food sources also can alter gene expression, increasing pathogenicity and decreasing the infectious dose. Understanding this “ecology” could prove crucial for predicting and preventing foodborne outbreaks.

Greens and produce are major sources of foodborne pathogens, many of which can thrive when greens are cut and processed during food preparation. Produce is the leading source of foodborne illness commonly caused by Salmonella enterica or Escherichia coli O157:H7 on leafy greens, according to Maria Brandl of the U.S. Department of Agriculture (USDA) in Albany, Calif.

“The continuous rise in the number of outbreaks of foodborne illness linked to fresh fruit and vegetables challenges the notion that enteric pathogens are defined mostly by their ability to colonize the intestinal habitat,” she says. “Enteric pathogens utilize diverse and overlapping strategies to interact with plants and their microflora, and to successfully colonize vertebrate hosts.”

5 Things Everyone Should Know About Washing Food (via Quest)

My friend, Matt Shipman, a science writer and public information officer at North Carolina State University writes in the below Quest North Carolina post about washing food (reprinted with permission):

464.thumbnailEverybody eats, and no one wants to eat something that could make you sick.  But there’s a lot of misinformation out there about how and whether you should wash your food.

Food safety is an important issue.  The U.S. Centers for Disease Control and Prevention estimates that each year one in six people in the United States will get sick because of food-borne illness.  And risks can be increased or decreased at every point between the farm and your fork.  Yes, you want to make sure to cook your food to the appropriate temperature, but here are some other tips to help you make good decisions in the kitchen.IMG_8159-sink-16x9-640x360

1. Don’t Wash Meat

Some people think that you’re supposed to wash chicken, turkey, or other meats before cooking.  Those people are wrong.  “Research shows that washing meat can spread dangerous bacteria around your kitchen or food preparation area,” said Ben Chapman, a food safety researcher at North Carolina State University.  “And washing poultry under running water can spray surface contamination up to three feet away.  We cook meat to make it safer; washing meat can only make a meal riskier.”

2. Washing Fruits and Veggies Only Removes up to 99 Percent of Pathogens

“That seems good, but it’s not great,” Chapman said.  By comparison, cooking food can cut the number of bacteria or other microbial pathogens by 99.9999 percent.  And that 0.9999 percent difference can be important.  If a food is contaminated by thousands of microbes, washing off 99 percent means that dozens will be left behind — and that’s enough to make you sick.  That is why people who are immunocompromised, such as some chemotherapy patients, are often discouraged from eating raw fruits and vegetables.

3. Don’t Use Soap

“Although washing has its limitations, vigorously rinsing produce under running water is the most effective way to remove the microbes that cause foodborne illnesses,” Chapman said.  You don’t need to use soap or special cleaning solutions.  In fact, using soap can actually introduce additional risk, because soaps may contain chemicals that aren’t intended for human consumption.

4. You Can’t Get All the Pesticides Off Your Food (but Don’t Panic)

Some minute traces of pesticide will probably be on — or in — your fruits or vegetables when you eat them.  “But being able to detect a pesticide doesn’t mean that it’s a public health problem,” said Chris Gunter, a researcher at NC State who studies vegetable agriculture.  That’s because, after using a pesticide, farmers are required to wait for a specific period of time before harvesting (it’s called a “pre-harvest interval”).  During that time, the pesticide breaks down or washes off, meaning any residual pesticide meets EPA’s human health requirements.

5. Even Organic Food Can Use a Rinse

Just because produce is labeled “organic” doesn’t mean that it’s somehow immune to microbial contamination. Organic farmers usually grow their fruits and vegetables in open fields, just like conventional farmers, and are subject to some of the same risks, such as fecal contamination from wildlife (that is, poop can still get on the food).

“Any time you’re going to eat fresh produce you should rinse it off, if for no other reason than to rinse off dirt,” said Don Schaffner, a food safety researcher at Rutgers.  “And rinsing off produce may offer some risk reduction in terms of microbial pathogens.”

Bonus: Don’t Wash Pre-Washed Veggies

If you’ve bought salad mix that is labeled as “pre-washed,” you really don’t need to wash it again, Schaffner said. In fact, you probably shouldn’t wash it again.  “An expert panel reported in 2007 that consumers who wash these salads again won’t reduce the risk,” Schaffner said, “and may actually create a risk of cross-contamination” where pathogens from other foods get onto the salad.  In this case, being lazy is a virtue. 

Distributions of Salmonella subtypes differ between two U.S. produce-growing regions

Salmonella accounts for approximately 50% of produce-associated outbreaks in the United States, several of which have been traced back to contamination in the produce production environment. To quantify Salmonella diversity and aid in identification of Salmonella contamination sources, we characterized Salmonella isolates from two geographically diverse produce-growing regions in the United States.

supermarket_produce Initially, we characterized the Salmonella serotype and subtype diversity associated with 1,677 samples collected from 33 produce farms in New York State (NYS). Among these 1,677 samples, 74 were Salmonella positive, yielding 80 unique isolates (from 147 total isolates), which represented 14 serovars and 23 different pulsed-field gel electrophoresis (PFGE) types. To explore regional Salmonella diversity associated with production environments, we collected a smaller set of samples (n = 65) from South Florida (SFL) production environments and compared the Salmonella diversity associated with these samples with the diversity found among NYS production environments. Among these 65 samples, 23 were Salmonella positive, yielding 32 unique isolates (from 81 total isolates), which represented 11 serovars and 17 different PFGE types.

The most common serovars isolated in NYS were Salmonella enterica serovars Newport, Cerro, and Thompson, while common serovars isolated in SFL were Salmonella serovars Saphra and Newport and S. enterica subsp. diarizonae serovar 50:r:z. High PFGE type diversity (Simpson’s diversity index, 0.90 ± 0.02) was observed among Salmonella isolates across both regions; only three PFGE types were shared between the two regions. The probability of three or fewer shared PFGE types was <0.000001; therefore, Salmonella isolates were considerably different between the two sampled regions. These findings suggest the potential for PFGE-based source tracking of Salmonella in production environments.

Appl. Environ. Microbiol. July 2014 vol. 80 no. 13 3982-3991 doi: 10.1128/AEM.00348-14

Laura K. Strawna, Michelle D. Danylukb, Randy W. Woroboa and Martin Wiedmann

http://aem.asm.org/content/80/13/3982.abstract.html?etoc

The limitations of washing fresh produce at home

A couple of weeks ago my friend Matt Shipman, who runs The Abstract, asked me to answer a question about the best way to wash produce in the home.

I’ve received different iterations of this question up from extension agents, media and at Food Safety Talk with Don Schaffner. I’ve sort of settled on this: use water, vigorously running out of the tap, but don’t expect washing to make your produce risk-free. HE_washing-pepper_s4x3_lead

I used to say that washing in the home did nothing for food safety but Don, the smart math dude I hangout with electronically, reminded me that saying it does nothing is incorrect – it does something.

Just not as much as folks may expect.

Matt captured the discussion for a blog post, below.

Here’s the question we got: “What is the most effective means of cleaning fresh produce at home to remove micro-organisms that could make you sick?”

“Vigorously rinsing the produce under running water is the most effective way of removing the microbes that cause foodborne illnesses – you don’t need soap or any special cleaning products,” says Ben Chapman, a food safety researcher at NC State. “But while washing your produce may remove some pathogens, it doesn’t eliminate risk altogether.”

“At best you get a two log reduction – that’s a 99 percent reduction in microbes,” Chapman says. “That seems good, but it’s not great. While washing can help reduce pathogen contamination, it shouldn’t be relied on as the only control measure.”

By comparison, cooking food results in a six log reduction in viable microbes. That means the population of viable microbes gets cut by 99.9999 percent(!).

The difference between 99 percent and 99.9999 percent is important because some fruits and vegetables can be contaminated with thousands of microbes. And we know that, on average, most microbial food-borne illnesses are caused by foods that are contaminated by only 20-30 organisms (the mean infectious dose for some of the pathogens of concern -ben).

So washing off 99 percent of the microbes doesn’t help much if a food was carrying thousands of microbes to start with. 

Buy from producers who know what the risks are and are employing strategies to reduce them. Ask lots of questions.

Some good references on how I’ve arrived at my answer are here: Bassett and McClure 2008Parish et al., 2003; Parnell et al., 2005; Verrill et al., 2012. There are other good ones out there too including this fact sheet from Christine Bruhn and others.

Aerosol sanitization to control pathogens on produce

An economical aerosol sanitization system was developed based on sensor technology for minimizing sanitizer usage, while maintaining bactericidal efficacy.

Aerosol intensity in a system chamber was controlled by a position-sensitive device and its infrared value range. The effectiveness of the infrared sensor–based aerosolization (ISA) system to inactivate Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on spinach leaf surfaces was compared with conventional aerosolization (full-time aerosol treated), and the amount of sanitizer consumed was determined after operation.

berries.may.14Three pathogens artificially inoculated onto spinach leaf surfaces were treated with aerosolized peracetic acid (400 ppm) for 15, 30, 45, and 60 min at room temperature (22 ± 2°C). Using the ISA system, inactivation levels of the three pathogens were equal or better than treatment with conventional full-time aerosolization. However, the amount of sanitizer consumed was reduced by ca. 40% using the ISA system. The results of this study suggest that an aerosol sanitization system combined with infrared sensor technology could be used for transportation and storage of fresh produce efficiently and economically as a practical commercial intervention.

 Infrared sensor–based aerosol sanitization system for controlling Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on fresh produce

Journal of Food Protection, Number 6, June 2014, pp. 872-1042, pp. 977-980(4)

Kim, Sang-Oh; Ha, Jae-Won; Park, Ki-Hwan; Chung, Myung-Sub; Kang, Dong-Hyun

http://www.ingentaconnect.com/content/iafp/jfp/2014/00000077/00000006/art00015

Because some companies are better at food safety; Martori adopts new food-safety program for cantaloupes

I can’t really assess whether these companies are actually better at food safety, but they’re willing to brag about it.

They get a balls-up from me.

cantaloupe.salmonellaTad Thompson of The Produce News writes that Martori Farms, headquartered in Scottsdale, Arizona, is fully activating a new type of food-safety program for packing cantaloupes.

The process, which employs a hot water shower to clean pathogens from the melons’ rough skin, looks to address critical food-safety issues that were ultimately related to the crevices in cantaloupe rinds

Stephen Martori Sr., president of the company, said his firm is one of two companies using this technology.

Martori built this hot water facility in its Aguila, AZ, packinghouse. Martori grows cantaloupes not only in Aguila but also in two other large farms, including one near Yuma, AZ. The firm is in the market seven months a year, shipping melons from May 1 through November.

The hot water shower was developed, beginning several years ago, through close cooperation with the U.S. Department of Agriculture’s Eastern Regional Agricultural Research Center in the Philadelphia suburb of Wyndmoor, PA. The research led to Martori’s system, which was commercially implemented in late April for the firm’s 2013 season launch.

The water shower lasts for approximately 20 seconds on each cantaloupe, which is rotated during the process. Targeting a water temperature of 162 degrees F, this brief hot water bath pasteurizes the skin, but is brief enough to avoid heating or injuring the cantaloupe’s flesh.

Martori Farms generally plans 1,000 in-house lab samples a season in its packinghouse. It has customers that want lab samples on the packingline of their specific orders.

In the peak of the coming Arizona cantaloupe season, Martori will pack more than 35,000 cantaloupes an hour, or approximately 400,000 melons a day.

“We are one of the largest melon grower-shippers in the country,” Martori said.

Cantaloupe accounts for 75 percent of the melon production at the firm, which produces more than 7,000 acres of melons, including 700 acres of watermelons.

Mini-watermelons and honeydew are also grown, packed and shipped by Martori. Among the honeydew offerings is its exclusive variety in North America, the Lemondrop.

In related news, Liberty Fruit Co. Inc. of Kansas City has earned the highest-possible food-safety rating, according to Scott Danner, the firm’s chief operating officer.

Danner said meeting the highest standards involves intensive training for all employees. He said all employees must pass individual tests for the correct food-safety protocols. Such questions may be as basic as, “What do you do if milk spills in the lunch room.” If someone in the organization doesn’t have the right answer, “We fail the audit,” said Danner.

Danner noted, “The hardest part of the process is to communicate with the rank-and-file. Without our loyal employees, we could not have done this. But they wanted to get involved.”

That’s a lot of poop: nearly 179 million cases of acute diarrhea occur each year in US

Washing produce is never enough, but that’s what a researcher says in a review of causes of foodborne illness. A better suggestion would be rigorous on-farm food safety programs.

lettuceIn the United States, approximately 179 million cases of acute diarrhea occur each year, and most of those cases are entirely preventable, a researcher from The University of Texas Health Science Center at Houston (UTHealth) concluded in a New England Journal of Medicine review article.

Herbert L. DuPont, M.D., director of the Center for Infectious Diseases at the UTHealth School of Public Health, examined current causes, prevention strategies and treatment for acute diarrhea in healthy adults. He says the main causes of diarrheal infections include norovirus outbreaks and foodborne pathogens, with most coming from contaminated leafy green vegetables.

Produce is the most common source of diarrhea due to foodborne intestinal illness. Most consumers are not aware that 98 percent of spinach and lettuce bought from grocery stores is not inspected and much of it comes from developing countries. One study showed that of the 2 percent that is inspected, 40 percent failed inspection and could be contaminated by diarrhea-producing E. coli or Salmonella.

“Consumers need to give their leafy greens a bath and a shower in order to make sure they are safe to eat,” says DuPont, instructing that leafy greens must be soaked in a bowl of water or the sink and then rinsed thoroughly by running water through a colander before consumption in order to avoid contaminants.

Europe assesses the risk of Salmonella and Norovirus in leafy greens

Rainfall, use of contaminated water for irrigation or contaminated equipment are among the factors that cause contamination of leafy greens with Salmonella and Norovirus. These are some of the findings of EFSA’s latest opinion on risk factors that contribute to the contamination of leafy greens at different stages of the food chain. The BIOHAZ Panel has lettuce.skull.e.coli.O145recommended that producers use good agricultural, hygiene and manufacturing practices to reduce contamination. The Panel has also proposed specific microbiological criteria at primary production.

Leafy greens eaten raw as salads are minimally processed and widely consumed foods. Risk factors for leafy greens contamination by Salmonella spp. and Norovirus were considered in the context of the whole food chain including agricultural production and processing. Available estimates of the prevalence of these pathogens (together with the use of Escherichia coli as an indicator organism) in leafy greens were evaluated. Specific mitigation options relating to contamination of leafy greens were considered and qualitatively assessed. It was concluded that each farm environment represents a unique combination of numerous characteristics that can influence occurrence and persistence of pathogens in leafy greens production. Appropriate implementation of food safety management systems, including Good Agricultural Practices (GAP), Good Hygiene Practices (GHP) and Good Manufacturing Practices (GMP), should be primary objectives of leafy green producers. The relevance of microbiological criteria applicable to production, processing and at retail/catering were considered. The current legal framework does not include microbiological criteria applicable at primary production which will validate and verify GAP and GHP. It is proposed to define a criterion at primary production of leafy greens which is designated as Hygiene Criterion, and E. coli was identified as suitable for this purpose.

A Process Hygiene Criterion for E. coli in leafy green packaging plants or fresh cutting plants was considered and will also give an indication of the degree to which GAP, GHP, GMP or HACCP programs have been implemented. A Food Safety Criterion for Salmonella in leafy greens could be used as a tool to communicate to producers and processors that Salmonella should not be present in the product. Studies on the prevalence and infectivity of Norovirus are limited, and quantitative data on viral load are scarce making establishment of microbiological criteria for Norovirus on leafy greens difficult.