The Packer writs in an editorial that the produce industry is justified in being upset about the latest accusation of lax food safety practices, but also acknowledges the industry has a strong food safety message and should be eager to share it.
It’s important that retailers and foodservice providers know the industry’s response to the most recent attack, this time from a United Kingdom study that raises concerns about salmonella in bagged salads.
How to do that?
Because at retail, the person consumers are going to ask is some minimum-wage kid who is stocking produce when a shopper walks by.
Most people want to go shopping, not do homework.
They are an abundance of tools that have been developed to help support risk communication at retail.
On the front lines.
Where sales are won and lost.
Market microbial food safety at retail rather than offering boilerplates.
I based a large part of my research career on verifying the soundbite, ‘we have released guidelines’ or, ‘we follow all recommendations’ by arranging to have students see what actually goes on.
In October 2014, the New South Wales Food Authority released Food Safety Guidelines for the Preparation of Raw Egg Products (the Guidelines). Despite this, outbreaks continued to take place, particularly where business hygiene and temperature control issues were apparent. In addition, businesses and councils approached the Food Authority for advice on desserts containing raw eggs and other unusual raw egg dishes. As a result, the Guidelines were recently updated and give specific reference to Standard 3.2.2, Division 3, clause 7 of the Australia New Zealand Food Standards Code to ensure that only safe and suitable food is processed.
To reduce the risk of foodborne illness outbreaks caused by Salmonella, retail businesses are advised to avoid selling food containing raw or minimally cooked eggs. The Guidelines give food businesses that do sell food containing raw egg specific safety steps for its preparation and clear guidance and advice on what they must do to meet food safety regulations. The revised Food Safety Guidelines for the Preparation of Raw Egg Products is available at www. foodauthority.nsw.gov.au/_Documents/ retail/raw_egg_guidelines.pdf.
This is nice but of no use to consumers at a restaurant who order fish and chips with a side of mayo or aioli. I’ve already begun an ad hoc investigation – because I don’t want my family to get sick – and can say that out of the 15 times I’ve asked over the past few years – is the aioli or mayo made at the restaurant or bought commercially – the server invariably returns and proclaims, We only use raw eggs in our aioli or mayo.
Only once, so far, has an owner or chef said, we know of the risk, we only use the bought stuff. And they’re ex-pat Canadians.
Ashley Nickle of The Packer reports that Bruce Taylor, CEO and founder of Salinas, Calif.-based Taylor Farms, emphatically denounced the study.
“We find the artificial conditions created by this study to be ridiculous,” Taylor said in an e-mail. “Producers of bagged salads do not have ‘juice’ in the salad bag, and producers take painstaking steps to avoid the introduction of salmonella or any other pathogen.”
The conclusion regarding refrigeration was the only notable one in the study, said Trevor Suslow, a member of the technical committee of the Center for Produce Safety. Scientists would expect salmonella to be able to survive at the temperature recorded in the study but would not expect it to grow, he said.
“People will definitely be trying to reproduce their results as far as growth under refrigeration temperature for salmonella,” Suslow said. “That’s, for me, the key issue.”
Suslow, an extension research specialist at the University of California-Davis, said it is already known that a bagged salad is an environment in which salmonella can have the nutrients it needs to grow, which is why the industry has focused so intently on ensuring no pathogens make it into bags into the first place.
Drew McDonald, vice president of quality, food safety and regulatory affairs at Salinas-based Church Brothers Farms, said in an e-mail that, although the researchers did some things well, he also had some issues with the study.
“From my read, the study essentially grew salmonella in juices extracted from actual bagged salads in a mixture of sterile water,” McDonald said. “The issue is that in the ‘real’ world the salmonella has to come from somewhere (the surface of the leaf for example) but along with this would be many other microorganisms. That they were able to grow salmonella under these forced, artificial conditions without any competition from other organisms is not surprising.”
Along with the growth conditions, the washed status of the lettuce also gave McDonald pause.
“From my understanding, (the) project used ‘bagged salad,’” McDonald said. “I am assuming this means it was already washed. The fact that they added salad juice and salmonella after it had already been bagged and washed really just shows how important it is to not cross-contaminate cleaned product.”
The researchers, as a result of their findings, suggested people eat bagged salads as soon as possible after purchase to minimize risk. They wrote in a question-and-answer supplement to the release that they no longer keep their bagged salads in the refrigerator longer than one day.
“Ridiculous recommendation,” Taylor said in his e-mail. “For 30 years consumers have enjoyed hundreds of millions of bagged salads weekly with great benefit to their health and wellbeing.”
Jennifer McEntire, vice president of food safety and technology at United Fresh Produce Association, also disagreed with the recommendation.
“People should always follow the instructions, including best-by dates, on packages, mainly so that they experience the best quality product,” McEntire said in an e-mail. “People shouldn’t be afraid to keep salad in their refrigerators for the full duration of the shelf life.”
She may mean use-by dates.
Suslow described the study as another piece of the puzzle in trying to find long-term solutions for food safety issues, but he was not impressed by it.
“Sort of generating a lot of additional concern and fear without any real basis for changing what (is) sort of standard practice isn’t necessarily helpful,” Suslow said. “Could hurt the category, but probably no more so than other things such as those instances when there are outbreaks or recalls.
“I think consumers understand that there’s no such thing as zero risk,” Suslow said (smartest thing anyone said in this story). “They understand and appreciate the convenience of packaged salads with multiple ingredients with very healthy mixed leafy greens, and that’s how the category has grown.”
I’ve been a long-time proponent that those farmers, processors and retailers that are really good at microbial food safety should be able to market such evidence directly to consumers.
This has nothing to do with food safety being a non-competitive issue, or whatever else industry types claim: It has everything to do with providing a market-based incentive for those in the farm-to-fork food safety system to brag about what they do.
There are good actors, there are bad actors: if trade associations were really concerned about their customers barfing, they’d stop saying everyone cares about food safety and support efforts to make such information readily available at retail.
But such microbiologically-safe claims are only valid with publicly available data: And there’s no such thing as no risk – or no Salmonella.
As that foodborne Salmonella infections in Denmark reached a historic low, some Danish processors are, according to Steve Sayer of Meatingplace.com, claiming on labels their chicken is Salmonalla-free.
Right, is a retail package containing raw skinless/boneless chicken that was recently purchased in Denmark (DK) Europe.
The labeling on the package is claiming to Danish consumers (where there’s an orange drawing of a chicken within a round circle): “Dansk Salmonelllafri Kylling,” when translated means – “Danish salmonella-free chicken.”
The DK packer is Rose Packing that claims their chicken is “salmonella free” on their website.
The long and winding road that the Danes labored to lowering salmonella within their hatcheries, layer hens, broiler chickens and eggs are impressive.
In 2015 a total of 925 salmonella infections were reported among Danes, which is equivalent to 16.2 infected cases per 100,000 inhabitants. This is the lowest number of salmonella infections since 1988, which is the first year from which researchers at the National Food Institute have used data to map the sources of foodborne salmonella infections.
2015 is also the first year since the introduction of the salmonella source account that Danish eggs have not caused illness. There have also been no registered cases of infection due to Danish chicken meat, which has been the case in four of the previous five years.
“The good results regarding Danish eggs and poultry are very encouraging. However, salmonella still constitutes a risk. Therefore it is important to maintain the preventive measures that researchers, governments and industry have jointly implemented over the years to ensure that salmonella is kept out of Danish products,” Senior Scientific Officer Birgitte Helwigh from the National Food Institute says.
Campylobacter continued to be the cause of most of the registered foodborne infections in Denmark in 2015 with 4,348 cases of illness. This represents a 15% increase from 2014 and is the highest number of cases ever recorded.
Improvements in the reporting system and changes in diagnostic methods mean that more cases of illness are registered than in the past. Therefore it is unclear whether more people actually got a campylobacter infection in 2015 compared to previous years.
In 2015, only 39 foodborne disease outbreaks have been registered. This is the lowest number of outbreaks since a nationwide database for food and waterborne disease outbreaks was established almost ten years ago. A total of 1,233 people have become sick in connection with the 39 outbreaks.
As in previous year norovirus was the leading cause of outbreaks (42%).
My new best friend – Ted, the dog – came from a breeder in Toowoomba, about 90 minutes away, atop Australia’s Great Dividing Ridge.
He weighs less than our cats, but is feisty and loves a walk.
Or a run.
The breeder (we went to the local shelters, but they had dogs that were not deemed appropriate by our townhouse body corporate) so we got the little one rather than make a rush decision to buy an $800K house so we could have a bigger dog.
Besides, this one’s got personality.
The breeder insisted that dogs do better on a raw meat diet.
I just wanted to get the dog, go visit our friends, and go home, so didn’t belabor the point.
But any raw product carries the same risk of Salmonella and E. coli and other things that are not fun to inflict on your dog.
The U.S. Centers for Disease Control (CDC) is working with Wisconsin health, agriculture, and laboratory agencies, several other states, and the U.S. Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS) to investigate a multistate outbreak of multidrug-resistant Salmonella Heidelberg infections.
Portrait of the cute baby bull calf
Public health investigators used the PulseNet system to identify illnesses that may have been part of this outbreak. PulseNet, coordinated by CDC, is the national subtyping network of public health and food regulatory agency laboratories. PulseNet performs DNA fingerprinting on Salmonella bacteria isolated from ill people by using techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks.
Twenty-one people infected with an outbreak strain of Salmonella Heidelberg have been reported from eight states.
Among 19 people with available information, illnesses started on dates ranging from January 11, 2016 to October 24, 2016. Ill people range in age from less than 1 year to 72, with a median age of 21. Sixty-two percent of ill people are female. Among 19 ill people with available information, 8 (42%) reported being hospitalized, and no deaths have been reported.
WGS showed that isolates from ill people are closely related genetically to one another. This close genetic relationship means that people in this outbreak are more likely to share a common source of infection.
Epidemiologic, traceback, and laboratory findings have identified dairy bull calves from livestock markets in Wisconsin as the likely source of infections. Dairy bull calves are young, male cattle that have not been castrated and may be raised for meat. Dairy bull calves in this outbreak have also been purchased for use with 4-H projects.
In interviews, ill people answered questions about any contact with animals and foods eaten in the week before becoming ill. Of the 19 people interviewed, 15 (79%) reported contact with dairy bull calves or other cattle. Some of the ill people interviewed reported that they became sick after their dairy bull calves became ill or died.
One ill person’s dairy calves were tested for the presence of Salmonella bacteria. This laboratory testing identified Salmonella Heidelberg in the calves. Further testing using WGS showed that isolates from ill people are closely related genetically to isolates from these calves. This close genetic relationship means that the human infections in this outbreak are likely linked to ill calves.
As part of routine surveillance, the Wisconsin State Laboratory of Hygiene, one of seven regional labs affiliated with CDC’s Antibiotic Resistance Laboratory Network, conducted antibiotic resistance testing on clinical isolates from the ill people associated with this outbreak. These isolates were found to be resistant to antibiotics and shared the same DNA fingerprints, showing the isolates were likely related to one another.
WGS identified multiple antimicrobial resistance genes in outbreak-associated isolates from fifteen ill people and eight cattle. This correlated with results from standard antibiotic resistance testing methods used by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory on clinical isolates from two ill people in this outbreak. The two isolates tested were susceptible to gentamicin, azithromycin, and meropenem. Both were resistant to amoxicillin-clavulanic acid, ampicillin, cefoxitin, ceftriaxone, chloramphenicol, nalidixic acid, streptomycin, sulfisoxazole, tetracycline, and trimethoprim-sulfamethoxazole and had reduced susceptibility to ciprofloxacin. Antibiotic resistance limits treatment options and has been associated with increased risk of hospitalization, bloodstream infections, and treatment failures in patients.
Traceback information available at this time indicates that most calves in this outbreak originated in Wisconsin. Wisconsin health and agriculture officials continue to work with other states to identify herds that may be affected.
The Atlanta Journal-Constitution reported that in January 2006, Nestle also rejected the company’s Plainview, Texas, plant after finding dozens of dead mice rotting in and around the plant, dead pigeons near a peanut receiving door and live birds roosting inside the plant.
Congressional types also heard that auditors AIB — also known as the American Institute of Baking based in Manhattan (sigh, Kansas) — were hired and paid by Peanut Corp. of America, notified the company in advance when they were coming, how to prepare for inspections and then gave its plants glowing reviews.
An inspector with AIB wrote to the manager of Peanut Corp.’s Blakely, Ga., in a December 2008 e-mail produced by the committee, “You lucky guy. I am your AIB auditor. So we need to get your plant set up for any audit.”
Mackay told the committee a version of, “how the hell could we know?” and that AIB is the most commonly used inspector by food companies in America.
He also wanted food safety placed under a new leader in the Health and Human Services department, called for new requirements that all food companies have written safety plans, annual federal inspections of facilities that make high-risk foods, and other reforms.
Kellogg’s is a multi-billion dollar company asking for a government handout to do what Kellogg’s should be doing – selling a safe product. Kellogg’s helped create the paper albatross that is third-party audits instead of having its own people at plants that supply product which Kellogg’s resells at a substantial profit. Kellogg’s crapmeister told Washington how to strengthen food safety when he couldn’t keep shit out of his own company’s peanut cracker thingies.
This is a company founded on fairytales and colonic cleansing in Michigan, making its money selling sugar-sweetened treats to kids and their parents, and using a sliver of those profits to sanctimoniously fund so-called research and training, using Michigan State University as their willing vessel.
With this background, it’s not surprising that, as reported by Dan Flynn of Food Safety News, that, “In mid-2007, Michael collaborated with his brother, Stewart Parnell, who was the President and CEO of Peanut Corporation of America, a peanut processing and manufacturing company, to provide peanut paste to Kellogg.”
P.P sales “was a small operation with two tanker trucks and one customer: Kellogg Company.
From mid-2007 to 2008, Michael shipped peanut paste from PCA’s Blakely, Georgia plant (PCA Blakely) to a Kellogg production facility in Cary, North Carolina.”
P.P.’s tanker trucks, filled with peanut paste, during those months were making 1,200 round-trips to provide the product Kellogg’s needed to put a little dab of peanut paste on all those Keebler PB sandwich crackers.
When anyone from Kelloggs talks about food safety, have a chuckle and move on; or tell them what dickshits they are and how they know nothing about food safety.
Audits and inspections are never enough: A critique to enhance food safety
D.A. Powell, S. Erdozain, C. Dodd, R. Costa, K. Morley, B.J. Chapman
Internal and external food safety audits are conducted to assess the safety and quality of food including on-farm production, manufacturing practices, sanitation, and hygiene. Some auditors are direct stakeholders that are employed by food establishments to conduct internal audits, while other auditors may represent the interests of a second-party purchaser or a third-party auditing agency. Some buyers conduct their own audits or additional testing, while some buyers trust the results of third-party audits or inspections. Third-party auditors, however, use various food safety audit standards and most do not have a vested interest in the products being sold. Audits are conducted under a proprietary standard, while food safety inspections are generally conducted within a legal framework. There have been many foodborne illness outbreaks linked to food processors that have passed third-party audits and inspections, raising questions about the utility of both. Supporters argue third-party audits are a way to ensure food safety in an era of dwindling economic resources. Critics contend that while external audits and inspections can be a valuable tool to help ensure safe food, such activities represent only a snapshot in time. This paper identifies limitations of food safety inspections and audits and provides recommendations for strengthening the system, based on developing a strong food safety culture, including risk-based verification steps, throughout the food safety system.
Both the vegetables were targeted by the agency’s proactive testing because of their role in previous outbreaks. Because cucumbers are often eaten raw, bacteria on them are more likely to make it into food; raw cucumbers have been blamed in five outbreaks of illness from 1996 to 2014.
Hot peppers, such as jalapeño and serrano peppers, on the other hand, are often cooked but can be a “stealth component” of multi-ingredient dishes, the FDA said. In 2008, hot peppers were implicated in an outbreak that caused 1,500 illnesses, 308 hospitalizations, and two deaths.
The FDA’s proactive sampling program began testing for disease-causing microbes in certain foods in 2014 to learn more about the prevalence of disease-causing bacteria and to help the agency identify patterns that may help predict and prevent future contamination.
The latest findings, released lastThursday, included results from 1,050 cucumber samples and 1,130 hot pepper samples. Eventually 1,600 of each will be sampled.
Of the cucumber samples, 15 tested positive for salmonella. None tested positive for E. coli. Of the hot pepper samples, 35 tested positive for salmonella, and one tested positive for a strain of Shiga toxin-producing E. coli that was determined to be incapable of causing severe illness.
The samples were collected at ports, packing houses, manufacturers, and distributors across the US.
The agency may take enforcement action, such as a recall, on foods that test positive.
In 2014, the FDA started a sampling program for a variety of commodities to learn more about the prevalence of disease-causing bacteria on the commodities.
The microbiological sampling assignments were designed to collect a statistically determined number of samples of certain commodities over 12 to 18 months and test them for certain types of bacteria that can cause foodborne illnesses.
That’s my response to people who ask about the proportionally high rates of foodborne illness in lettuce and other leafy greens eaten raw.
I like spinach – in a lasagna or stir-fry – but not raw.
Raw is risky.
There’s a bunch of new findings on foodborne pathogens and leafy greens which are summarized below.
In the sphere of public conversation, it is notable the Leafy Greens Marketing Agreement, the group formed after the 2006 E. coli-in-spinach outbreak that killed four and sickened at least 200 in the U.S. – has been once again silent on any research or outbreaks that associate risk with greens.
The scientists have discovered that juices released from damaged leaves also had the effect of enhancing the virulence of the pathogen, potentially increasing its ability to cause infection in the consumer.
The research is led by Dr Primrose Freestone of the University’s Department of Infection, Immunity and Inflammation and PhD student Giannis Koukkidis, who has been funded by a Biotechnology and Biological Sciences Research Council (BBSRC) i-case Studentship.
Their research investigates novel methods of preventing food poisoning pathogens from attaching to the surface of salad leaves to help producers improve food safety for consumers.
This latest study, published in Applied and Environmental Microbiology, found that juices from damaged leaves in bagged spinach and mixed salad increased Salmonella pathogen growth 2400-fold over a control group and also enhanced their adherence to surfaces and overall virulence, or capacity to cause disease.
Dr Freestone said: “Salad leaves are cut during harvesting and we found that even microliters of the juices (less than 1/200th of a teaspoon) which leach from the cut-ends of the leaves enabled Salmonella to grow in water, even when it was refrigerated. These juices also helped the Salmonella to attach itself to the salad leaves so strongly that vigorous washing could not remove the bacteria, and even enabled the pathogen to attach to the salad bag container.
“This strongly emphasizes the need for salad leaf growers to maintain high food safety standards as even a few Salmonella cells in a salad bag at the time of purchase could become many thousands by the time a bag of salad leaves reaches its use by date, even if kept refrigerated. Even small traces of juices released from damaged leaves can make the pathogen grow better and become more able to cause disease.
“It also serves as a reminder to consume a bagged salad as soon as possible after it is opened. We found that once opened, the bacteria naturally present on the leaves also grew much faster even when kept cold in the fridge.
“This research did not look for evidence of Salmonella in bagged salads. Instead, it examined how Salmonella grows on salad leaves when they are damaged.”
Leafy green and other salad vegetables are an important part of a healthy diet, providing vitamins, minerals, and dietary fiber. Ready to eat prepared salads are particularly popular, are widely consumed and so of significant economic importance. Over recent years there has however been a number of outbreaks associated with fresh salad produce contaminated with Salmonella and E. coli both in the USA and Europe.
This has triggered considerable interest in effective strategies for controls and interventions measures both in UK industry, the EU and key research funding bodies.
Despite a number of published reports on improving the microbiological safety of salad leaf production, very few studies have investigated the behavior of Salmonella once the leaves have been bagged.
Giannis said: “Anything which enhances adherence of foodborne pathogens to leaf surfaces also increases their persistence and ability to resist removal, such as during salad washing procedures. Even more worrying for those who might eat a Salmonella contaminated salad was the finding that proteins required for the virulence (capacity to cause infection) of the bacteria were increased when the Salmonella came into contact with the salad leaf juices. “Preventing enteric pathogen contamination of fresh salad produce would not only reassure consumers but will also benefit the economy due to fewer days lost through food poisoning. We are now working hard to find ways of preventing salad-based infections.”
No comment from the LGMA.
While this research may make it seem like pre-packaged salads pose a scary risk, the researchers themselves were quick to say they still eat bagged salads. But they make sure to look for packages that have appropriate use-by dates and crisp-looking leaves. They stay away from salads that have mushy, slimy-looking greens, or bags with accumulated salad juice at the bottom. And they make sure to eat the greens within one day of purchase.
“Our project does not indicate any increased risk to eating leafy salads, but it does provide a better understanding of the factors contributing to food poisoning risks,” said Freestone.
If you feel like it, you can wash greens that have already been pre-washed by manufacturers just before eating, but Freestone says this doesn’t have much of an effect on the salmonella bacteria that may already be attached or internalized by the leaves.
Foodborne disease outbreaks associated with fresh produce irrigated with contaminated water are a constant threat to consumer health. In this study, the impact of irrigation water on product safety from different food production systems (commercial to small-scale faming and homestead gardens) was assessed.
Hygiene indicators (total coliforms, Escherichia coli), and selected foodborne pathogens (Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7) of water and leafy green vegetables were analyzed. Microbiological parameters of all irrigation water (except borehole) exceeded maximum limits set by the Department of Water Affairs for safe irrigation water. Microbial parameters for leafy greens ranged from 2.94 to 4.31 log CFU/g (aerobic plate counts) and 1 to 5.27 log MPN/100g (total coliforms and E. coli). Salmonella and E. coli O157:H7 were not detected in all samples tested but L. monocytogenes was present in irrigation water (commercial and small-scale farm, and homestead gardens).
This study highlights the potential riskiness of using polluted water for crop production in different agricultural settings.
No comment from LGMA.
Adaptive response of Listeria monocytogenes to heat, salinity and low pH, after habituation on cherry tomatoes and lettuce leaves
Sofia V. Poimenidou, Danai-Natalia Chatzithoma, George-John Nychas, Panagiotis N. Skandamis
Pathogens found on fresh produce may encounter low temperatures, high acidity and limited nutrient availability. The aim of this study was to evaluate the effect of habituation of Listeria monocytogenes on cherry tomatoes or lettuce leaves on its subsequent response to inhibitory levels of acid, osmotic and heat stress.
Habituation was performed by inoculating lettuce coupons, whole cherry tomatoes or tryptic soy broth (TSB) with a three-strains composite of L. monocytogenes, which were further incubated at 5°C for 24 hours or 5 days. Additionally, cells grown overnight in TSB supplemented with 0.6% yeast extract (TSBYE) at 30°C were used as control cells. Following habituation, L. monocytogenes cells were harvested and exposed to: (i) pH 3.5 adjusted with lactic acid, acetic acid or hydrochloric acid (HCl), and pH 1.5 (HCl) for 6 h; (ii) 20% NaCl and (iii) 60°C for 150 s.
Results showed that tomato-habituated L. monocytogenes cells were more tolerant (P < 0.05) to acid or osmotic stress than those habituated on lettuce, and habituation on both foods resulted in more stress resistant cells than prior growth in TSB. On the contrary, the highest resistance to heat stress (P < 0.05) was exhibited by the lettuce-habituated L. monocytogenes cells followed by TSB-grown cells at 5°C for 24 h, whereas tomato-habituated cells were highly sensitized. Prolonged starvation on fresh produce (5 days vs. 24 h) increased resistance to osmotic and acid stress, but reduced thermotolerance, regardless of the pre-exposure environment (i.e., tomatoes, lettuce or TSB).
These results indicate that L. monocytogenes cells habituated on fresh produce at low temperatures might acquire resistance to subsequent antimicrobial treatments raising important food safety implications.
No comment from LGMA.
Efficacy of post-harvest rinsing and bleach disinfection of E. coli O157:H7 on spinach leaf surfaces
Attachment and detachment kinetics of Escherichia coli O157:H7 from baby spinach leaf epicuticle layers were investigated using a parallel plate flow chamber. Mass transfer rate coefficients were used to determine the impact of water chemistry and common bleach disinfection rinses on the removal and inactivation of the pathogen. Attachment mass transfer rate coefficients generally increased with ionic strength. Detachment mass transfer rate coefficients were nearly the same in KCl and AGW rinses; however, the detachment phase lasted longer in KCl than AGW (18 ± 4 min and 4 ± 2 min, respectively), indicating that the ions present during attachment play a significant role in the cells’ ability to remain attached. Specifically, increasing bleach rinse concentration by two orders of magnitude was found to increase the detachment mass transfer rate coefficient by 20 times (from 5.7 ± 0.7 × 10−11 m/s to 112.1 ± 26.8 × 10−11 m/s for 10 ppb and 1000 ppb, respectively), and up to 88 ± 4% of attached cells remained alive.
The spinach leaf texture was incorporated within a COMSOL model of disinfectant concentration gradients, which revealed nearly 15% of the leaf surface is exposed to almost 1000 times lower concentration than the bulk rinse solution.
No comment from LGMA.
Development of growth and survival models for Salmonella and Listeria monocytogenes during non-isothermal time-temperature profiles in leafy greens
Leafy greens contaminated with Salmonella enterica have been linked to large number of illnesses in many countries in recent years. Listeria monocytogenes is also a pathogen of concern for leafy greens because of its prevalence in the growing and processing environment and its ability to grow at refrigeration temperatures. Experimental data for the growth and survival of S. enterica and L. monocytogenes under different conditions and storage temperatures were retrieved from published studies. Predictive models were developed using the three-phase linear model as a primary growth model and square-root model to calculate specific growth rate (ln CFU g−1 h−1) at different temperatures (°C). The square-root model for S. enterica was calculated as μ = (0.020(Temperature+0.57))2. The square-root model for L. monocytogenes was fitted as μ = (0.023(Temperature-0.60))2. The growth-survival model for S. enterica and growth model for L. monocytogenes were validated using several dynamic time-temperature profiles during the production and supply chain of leafy greens. The models from this study will be useful for future microbial risk assessments and predictions of behavior of S. enterica and L. monocytogenes in the leafy greens production and supply chain.
No comment from LGMA.
Is there a relation between the microscopic leaf morphology and the association of Salmonella and Escherichia coli O157:H7 with iceberg lettuce leaves?
Journal of Food Protection, Number 10, October 2016, pp. 1656-1662, pp. 1784-1788(5)
I Van der Linden, M Eriksson, M Uyttendaele, F Devlieghere
To prevent contamination of fresh produce with enteric pathogens, more insight into mechanisms that may influence the association of these pathogens with fresh produce is needed.
In this study, Escherichia coli O157:H7 and Salmonella were chosen as model pathogens, and fresh cut iceberg lettuce was chosen as a model fresh produce type. The morphological structure of iceberg lettuce leaves (stomatal density and length of cell margins per leaf area) was quantified by means of leaf peels and light microscopy of leaves at different stages of development (outer, middle, and inner leaves of the crop) on both leaf sides (abaxial and adxial) and in three leaf regions (top, center, and bottom). The morphology of the top region of the leaves was distinctly different from that of the center and base, with a significantly higher stomatal density (up to five times more stomata), different cell shape, and longer cell margins (two to three times longer). Morphological differences between the same regions of the leaves at different stages of development were smaller or nonsignificant. An attachment assay with two attenuated E. coli O157:H7 strains (84-24h11-GFP and BRMSID 188 GFP) and two Salmonella strains (serovars Thompson and Typhimurium) was performed on different regions of the middle leaves. Our results confirmed earlier reports that these pathogens have a higher affinity for the base of the lettuce leaf than the top. Differences of up to 2.12 log CFU/g were seen (E. coli O157:H7 86-24h11GFP). Intermediate attachment occurred in the central region.
The higher incidence of preferential bacterial attachment sites such as stomata and cell margins or grooves could not explain the differences observed in the association of the tested pathogens with different regions of iceberg lettuce leaves.
No comment from LGMA.
The N.Y Times reportsthe one place the one place the Salinas Valley’s bounty of antioxidants does not often appear is on the tables of the migrant workers who harvest it.
More than a third of the children in the Salinas City Elementary School District are homeless; overall diabetes rates are rising and projected to soar; and 85 percent of farmworkers in the valley are overweight or obese, partly because unhealthy food is less costly, said Marc B. Schenker, a professor at the University of California, Davis, who studies the health of farmworkers.
As a Canadian in the U.S. I’ve fully embraced the holiday season that runs from Thanksgiving through December. I enjoy spending a day planning and shopping for an event-style meal, and then another day actually preparing and cooking it. I throw on some tunes (this year it will probably be Drake, for my Canadian roots, and the Avett Brothers as a nod to North Carolina) and with the help of the rest of the family I’ll roast a turkey, make mashed potatoes, green beans, squash, beets and a couple of other harvest vegetables.
And we’ll make a lot of stuffing.
Depending on your preference and food persuasion there are lots of different stuffing or dressing options.
A common question that pops up is whether it’s better to cook stuffing it in the bird to preserve moisture (and get flavored by the turkey juices) or prepare it as a separate dish. The concern is that if someone puts the stuffing in the turkey cavity it may become contaminated by the turkey juices and Salmonella and Campylobacter will migrate through the stuffing. Easier to recommend not messing with the cross-contamination instead of managing the risk. But what does the science say?
I’m a food safety nerd and take a science-based approached to my meals. Armed with a digital, tip-sensitive thermometer I’m happy to jam stuffing up inside of my poultry and use the probe to check the temperature. And I use 165 degrees Fahrenheit as a target for my bread-based stuffing.
There’s some history to that number; in 1958 Raymond Rogers and Millard Gunderson of the Campbell Soup Company published some work evaluating the safety of roasting frozen stuffed turkeys (a new product at the time). Using a known amount of Salmonella pullorum, nine turkeys and some then-fancy ceramic thermocouples, they found that they could get an 8-log (or 99.999999%) reduction when the deepest part of the stuffing hit 160 degrees Fahrenheit. They recommended 165 degrees to be conservative (and because some thermometers aren’t always very accurate).
From the manuscript (comments that still apply today): “The initial temperature and the size of the turkey influence considerably the time required to reach a lethal temperature in the stuffing. The lower the initial temperature of the turkey, the longer the roasting period required. Present recommended roasting procedures designating hours cooking time or which stipulate a thigh or breast temperature to be attained alone does not appear to be adequate bacteriologically.”
Inside the bird, outside the bird; meat or no meat: Use a thermometer.