Nicola Perry of Contagion Live writes that according to new research, applying antimicrobial coatings to whole cantaloupes during storage significantly reduces contamination by pathogenic bacteria, and has the potential to improve their microbiological safety and extend their shelf life.
Qiumin Ma, PhD, from the University of Tennessee in Knoxville, and colleagues published the results of their study in the International Journal of Food Microbiology. Chitosan-based coatings “significantly inhibited the growth of E[scherichia] coli O157:H7, L[isteria] monocytogenes and S[almonella] enterica cocktails on whole cantaloupes during 14-day storage at ambient temperature (21°C),” the authors write. “Coatings also significantly reduced total mold and yeast counts on whole cantaloupes.” Cantaloupes are particularly susceptible to microbial contamination because they grow on the ground and can therefore come into contact with foodborne-pathogens associated with polluted irrigation water, uncomposted manure, or animal droppings. They can also become contaminated during harvesting, handling, and preparation. The rough cantaloupe skin also allows bacteria to easily attach to the surface of the fruit.
“These pre- and post-harvest safety factors have directly or indirectly contributed to more than 25 outbreaks of foodborne illnesses associated with the consumption of cantaloupes between 1973 and 2003 in the United States and Canada,” the authors state.
Food preservation, safety, and quality maintenance therefore represent mounting concerns for the food industry. Antimicrobial food coatings represent just one form of technology that has been investigated as a tool to help improve food safety in various food types, including fresh produce and meats.
Chitosan, derived from the polysaccharide chitin, is known to have film-forming properties as well as antimicrobial activity. Chitosan-based coatings have also been shown to improve food safety—in fresh produce, for example. With this in mind, Dr. Ma and colleagues conducted a study to investigate the efficacy of such antimicrobial coatings in reducing bacterial populations from the surface of cantaloupes. In addition to chitosan, they investigated two generally-recognized-as-safe antimicrobials—lauric arginate (LAE; which inhibits a broad spectrum of foodborne pathogens) and cinnamon oil (CO; an essential oil that has shown activity against Listeria species, gram negative bacteria, E. coli 0157:H7, and Salmonella species). They also investigated ethylenediaminetetraacetic acid (EDTA; an agent that chelates divalent calcium ions that are important to bacterial structures; it also enhances the activity of some antimicrobials).
Cantaloupes, marketed as “Rocky Ford,” were implicated in the U.S. multistate outbreak of listeriosis in 2011, which caused multiple fatalities. Listeria monocytogenes can survive on whole cantaloupes and can be transferred to the flesh of melons.
The growth of L. monocytogenes on fresh-cut “Athena” and “Rocky Ford” cantaloupe cultivars during refrigerated storage was evaluated. Fresh-cut cubes (16.4 cm3) from field-grown cantaloupes were each inoculated with 5 log10 CFU/mL of a multi-strain mixture of L. monocytogenes and stored at 4°C or 10°C. Inoculated fresh-cut cubes were also: (1) continuously stored at 4°C for 3 days; (2) temperature-abused (TA: 25°C for 4 h) on day 0; or (3) stored at 4°C for 24 h, exposed to TA on day 1, and subsequently stored at 4°C until day 3. L. monocytogenes populations on fresh-cut melons continuously stored at 4°C or 10°C were enumerated on selected days for up to 15 days and after each TA event. Brix values for each cantaloupe variety were determined. L. monocytogenes populations on fresh-cut cantaloupe cubes stored at 4°C increased by 1.0 and 3.0 log10 CFU/cube by day 7 and 15, respectively, whereas those stored at 10°C increased by 3.0 log10 CFU/cube by day 7.
Populations of L. monocytogenes on fresh-cut cantaloupes stored at 10°C were significantly (p < 0.05) greater than those stored at 4°C during the study. L. monocytogenes showed similar growth on fresh-cut “Athena” and “Rocky Ford” cubes, even though “Athena” cubes had significantly higher Brix values than the “Rocky Ford” fruit.
L. monocytogenes populations on fresh-cut cantaloupes exposed to TA on day 1 and then refrigerated were significantly greater (0.74 log10 CFU) than those stored continuously at 4°C for 3 days. Storage at 10°C or exposure to TA events promoted growth of L. monocytogenes on fresh-cut cantaloupe during refrigerated storage.
Survival and growth of Listeria monocytogenes on fresh-cut “Athena” and “Rocky Ford” cantaloupes during storage at 4°C and 10°C
Nyarko Esmond, Kniel Kalmia E., Reynnells Russell, East Cheryl, Handy Eric T., Luo Yaguang, Millner Patricia D., and Sharma Manan. Foodborne Pathogens and Disease. August 2016, ahead of print. doi:10.1089/fpd.2016.2160.
I recycled an old op-ed in response, and still wondering why the same issues haven’t gained traction after 20 years of publicity in Australia.
The Advertiser editorial thingies wrote that irony can be really ironic, given that the government department charged with upholding and maintaining food standards in SA treats the public like mushrooms.
By keeping the public in the dark by refusing to release the names of the 621 food outlets in breach of hygiene rules last year, SA Health is denying consumers the right to make an informed choice.
While it is good enough for the NSW State Government to identify offending premises, those who water their gardens with human effluent, sell out of date food and have cockroach-infested kitchens in SA apparently deserve anonymity.
There is more than a whiff of double standards surrounding the secrecy of the data held by SA Health.
On one hand (who writes this crap?), the public is not allowed to know which of their local fast food outlets is cutting food hygiene corners by selling six-day-old schnitzels, and on the other, it wasted no time last week issuing a warning about NT- grown rockmelons being the apparent source of a food poisoning outbreak in SA.
Surely the public is allowed to know the identity of a food retailer that has been found guilty of a major breach of food standards that could potentially have the same impact as eating the dodgy rockmelon.
For a food outlet to be warned several times about using effluent to water gardens simply beggars belief.
SA Health’s repeated warnings to the business owner were akin to being slapped with a wet lettuce leaf.
If such a practice can continue for such an extended period of time, the public can only wonder just what sort of heinous breach of food safety regulations a business must commit to be jumped on immediately.
My response was:
I coach little kids’ (ice) hockey in Brisbane.
For that voluntary pleasure, I had to complete 16 hours of certification training, in addition to the 40 hours of training I completed in Canada to coach a travel team.
To produce or serve food in Australia requires … nothing.
Restaurants and food service establishments are a significant source of the foodborne illness that strikes up to 20 per cent of citizens in so-called developed countries each and every year.
After helping develop and watching the mish-mash of federal, state and local approaches to restaurant inspection and disclosure in a number of western countries for the past 15 years, I can draw two broad conclusions:
Anyone who serves, prepares or handles food, in a restaurant, nursing home, day care center, supermarket or local market needs some basic food safety training; and,
the results of restaurant and other food service inspections must be made public.
There should be mandatory food handler training, for say, three hours, that could happen in school, on the job, whatever. But training is only a beginning. Just because you tell someone to wash the poop off their hands before they prepare salad for 100 people doesn’t mean it is going to happen; weekly outbreaks of hepatitis A confirm this. There are a number of additional carrots and sticks that can be used to create a culture that values microbiologically safe food and a work environment that rewards hygienic behavior. But mandating basic training is a start.
Next is to verify that training is being translated into safe food handling practices through inspection. And those inspection results should be publicly available.
A philosophy of transparency and openness underlies the efforts of many local health units across North America in seeking to make available the results of restaurant inspections. In the absence of regular media exposes, or a reality TV show where camera crews follow an inspector into a restaurant unannounced, how do consumers — diners — know which of their favorite restaurants are safe?
Cities, counties and states are using a blend of web sites, letter or numerical grades on doors, and providing disclosure upon request. In Denmark, smiley or sad faces are affixed to restaurant windows.
Publicly available grading systems rapidly communicate to diners the potential risk in dining at a particular establishment and restaurants given a lower grade may be more likely to comply with health regulations in the future to prevent lost business.
More importantly, such public displays of information help bolster overall awareness of food safety amongst staff and the public — people routinely talk about this stuff. The interested public can handle more, not less, information about food safety.
Even in New South Wales and Queensland, results are only posted voluntarily.
So if an outlet sucks at food safety, they don’t have to tell anyone.
Toronto, Los Angeles and New York have had mandatory disclosure, on the doors for years.
Adelaide can figure it out.
And instead of waiting for politicians to take the lead, the best restaurants, those with nothing to hide and everything to be proud of, will go ahead and make their inspection scores available — today.
I’ve done lots of stuff with schoolkids over the years – food is a wonderful teaching tool – but this was tough.
There were 10 of us, judging about 180 projects at one elementary school.
Being the newbie, I got the prep (kindergarten) and grade 1s (grade 2 would have been a conflict of interest).
We had score sheets that will be returned to the students, and I thought, how do I evaluate this, I don’t want to crush the investigative soul of a 6-year-old.
It’s fair game to crush the souls of PhD students and other profs through peer-review, but this felt like peer-review for little kids.
I mainly wrote encouraging things and asked questions.
The things kids think of.
We have an awards thingy later tonight, with the all-Aussie sausage sizzle (yes, I will bring my tip-sensitive digital thermometer and use it, because that is the only data that matters when involving food safety), but I wonder if they’ll serve rockmelon (cantaloupe).
Contrary to what Australians are being told, cantaloupe – er, rockmelon – is a known source of foodborne illness and many scientists have investigated the many ways nasty bacteria get on or in the melon; along with potential treatments.
In this paper, researchers from the U.S. Department of Agriculture report surface structure and biochemical characteristics of bacteria and produce play a major role in how and where bacteria attach, complicating decontamination treatments.
Whole cantaloupe rind surfaces were inoculated with Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes at 107 CFU/ml. Average population size of Salmonella, Escherichia coli O157:H7, and L. monocytogenes recovered after surface inoculation was 4.8 ± 0.12, 5.1 ± 0.14, and 3.6 ± 0.13 log CFU/cm2, respectively. Inoculated melons were stored at 5 and 22°C for 7 days before washing treatment interventions. Intervention treatments used were (i) water (H2O) at 22°C, (ii) H2O at 80°C, (iii) 3% hydrogen peroxide (H2O2) at 22°C, and (iv) a combination of 3% H2O2 and H2O at 80°C for 300 s. The strength of pathogen attachment (SR value) at days 0, 3, and 7 of storage was determined, and then the efficacy of the intervention treatments to detach, kill, and reduce transfer of bacteria to fresh-cut pieces during fresh-cut preparation was investigated. Populations of E. coliO157:H7 attached to the rind surface at significantly higher levels (P < 0.05) than Salmonella and L. monocytogenes, but Salmonella exhibited the strongest attachment (SR value) at all days tested. Washing with 3% H2O2 alone led to significant reduction (P < 0.05) of bacteria and caused some changes in bacterial cell morphology. A combination treatment with H2O and 3% H2O2 at 8°C led to an average 4-log reduction of bacterial pathogens, and no bacterial pathogens were detected in fresh-cut pieces prepared from this combination treatment, including enriched fresh-cut samples.
The results of this study indicate that the microbial safety of fresh-cut pieces from treated cantaloupes was improved at day 6 of storage at 5°C and day 3 of storage at 10°C.
Effect of hydrogen peroxide in combination with minimal thermal treatment for reducing bacterial populations on cantaloupe rind surfaces and transfer to fresh cut pieces
1: U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA;, Email: firstname.lastname@example.org 2: U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA
Journal of Food Protection, August 2016, Number 8, Pages 1316-1324, DOI: http://dx.doi.org/10.4315/0362-028X.JFP-16-046
Red Dirt rockmelons in Australia’s Northern Territories, have tested positive for Salmonella, at least 97 people are sick across Australia, two major supermarkets are proclaiming their produce safe – in the absence of any supporting data — so the New South Wales Food Authority decided to tweet this morning, “Beware! Food poisoning can come from any food that isn’t handled correctly.”
It’s an animation, stunningly void of content.
And while it’s maybe part of a general campaign, because the majority of the 97 sick with Salmonella-in-rockmelon are based in NSW, maybe the food types have better things to do.
I’m not sure what is the right way to handle cantaloupe is, other than prevention – irrigation water, shit in the soil, dumptank cleanliness (if they are used) and employee sanitation – yet the regulators seem to have come up with their own version of blame-the-consumer (although once it’s cut, refrigerate immediately).
But that’s normal for outbreaks in Australia.
Soon, everyone will go back to sleep.
The only way to have more microbiological safety in foods is to demand it – through media coverage, social media, and marketing food safety, backed up with data.
Instead, all any growers are saying is, it wasn’t us, so please believe us when we tell you it is safe.
Show consumers the data.
Back it up with something other than platitutes.
And don’t fall for the organic, local sustainable, natural and gmo-free nonsense that has nothing to do with the things in food that make people barf.
The Australian Melon Association said the outbreak had now been contained.
“All rockmelons from the affected farm have been removed from supermarket and greengrocer shelves nationwide,” a statement released today said.
“The grower is working with the Northern Territory Health Department to review its operations and will not resupply the market until the all-clear has been given.
Woolworths and Coles have removed all Red Dirt rockmelons from their stores and suspended further orders while health authorities investigate the matter.
A spokesman for Woolworths said only 2.5 per cent of the supermarket’s rockmelon supply nationwide was from the affected farm.
“Customers can continue to purchase alternatively sourced rockmelons from Woolworths with confidence,” he said.
A Coles spokesman said Red Dirt supplied their stores in all states and territories with the exception of Tasmania and Western Australia.
I’m sorry that innocent growers are going to lose sales, but Salmonella and Listeria in rockmelon is nothing new. The best way to manage a crisis is to be prepared.
And don’t depend on associations or government or retailers to do anything other than a meaningless-Bill-Clinton-I-share-your-pain.
They will all still be employed when this moves on.
It’s all part of the active lifestyle thingy the school does – and our school is really good at it, because driving just doesn’t makes sense for the locals – but Sorenne’s scooter has seen better days and now she’s an avid bike rider.
She still got a sausage on white bread – breakfast of champions – and some fruit for her efforts.
The fruit this morning consisted of watermelon and orange slices. I asked the co-ordinator if she considered rockmelon — otherwise known as cantaloupe – and she said, I did last week, but then just didn’t.
And then I heard the news last night.
Food safety Doug, who ruins all the fun for the other kids, gave her a big thumbs up.
Later today, it was confirmed that at least 86 people in Australia have contracted an “exceedingly rare” form of salmonella linked to the consumption of rockmelon.
Red Dirt Melons – a Northern Territories-based supplier – is recalling its rockmelons after Food Standards Australia New Zealand (FSANZ) launched an investigation into a spike in salmonella cases in a number of Australian states.
Whole rockmelons, as well as pre-sliced melons, can carry the bacteria, and should be avoided, health authorities said.
There have been 86 reported cases of Salmonella Hvittingfoss (S. Hittingfoss) nationally – 43 cases in NSW – in the two weeks to August 1.
It’s a sizeable jump compared to the two cases per month on average in NSW over the last five years.
The people affected by the recent outbreak range in ages, but 49 per cent of cases in NSW were children under five years old.
Victorian authorities are investigating eight suspected cases of salmonella poisoning that may be linked to the fruit.
Red Dirt Melons have begun a recall of their rockmelons after the Salmonella bacteria was detected by health authorities in South Australia on August 2.
Woolworths removed all Red Dirt rockmelons from its stores on Monday evening when they were told of the possible link, a spokesman for the supermarket giant said.
The chain has also suspended any future supply from Red Dirt until the food authorities provide further guidance.
Rockmelons could become contaminated with salmonella due to water contamination, contact with fertiliser, pests or animals, or if the rockmelons were not cleaned properly before sale, The NSW Food Authority said.
Rockmelons have been linked to salmonella poisonings in the past, including in the US in the 1950s, 1960s and in 2002.
The Hvittingfoss strain turned up in Sydney and Adelaide in the past few weeks, according to the Australian Melon Association. Food Standards Australia New Zealand says authorities are investigating and has warned pregnant woman, infants and the elderly not to eat the fruit.
Industry, state and federal authorities are expected to discuss the issue in a teleconference on Wednesday afternoon.
“We want more details so consumers can find out which parts of Australia are not impacted,” melon association spokeswoman Dianne Fullelove told AAP.
“We would like to have our supply chain moving. At the moment it’s virtually stopped.”
Nicevmessage of safety and compassion.
The fruit has previously been linked to salmonella, with 50 cases linked to the Saintpaul strain reported in NSW in 2006. In America in 2011, rockmelon contaminated with listeria was linked to more than 20 deaths (33 – dp).
Rockmelon — otherwise known as cantaloupe – may be behind an increase of Salmonella in several Australian states.
Food Standards Australian New Zealand said Tuesday that, “While we wait for further information, the best advice is that consumers, especially infants, the elderly, pregnant women or people with compromised immune systems, should not consume rockmelon.”
Here we investigated the potential of strains from the 2011 cantaloupe outbreak to adhere, survive, and grow on cantaloupe rind and flesh and in juice extracted from cantaloupe at different temperatures (4, 8, and 25°C). All strains were able to adhere and grow, with ∼10-fold increases after 7 days at 4 or 8°C and after 24 h at 25°C, with a propensity for more growth on rind than on flesh or in extract. No significant differences in growth potential were noted among the different strains or between them and unrelated strains from other listeriosis outbreaks involving celery, deli meats, or hot dogs. Similarly to the cantaloupe outbreak strains, these other strains exhibited greater propensity for growth on rind than on flesh or in extract. Rinsing of cantaloupe fragments in sterile water resulted in temporary reductions of the populations by 50- to 100-fold, suggesting the potential of such washing to reduce risk if the produce is promptly consumed.
The absence of marked differences in adherence or growth between the cantaloupe outbreak strains and strains from other outbreaks highlights the need to further characterize the 2011 cantaloupe outbreak strains and elucidate potential biological attributes that contributed to their implication in the outbreak.
Capacity of Listeria monocytogenes strains from the 2011 cantaloupe outbreak to adhere, survive, and grow on cantaloupe
Journal of Food Protection®, Number 5, May 2016, pp. 696-889, pp. 757-763(7)
Martinez, Mira Rakic; Osborne, Jason; Jayeola, Victor Oladimeji; Katic, Vera; Kathariou, Sophia