What is the temperature of your fridge?

Posted on January 29, 2020 by Douglas Powell

I used to use these semi-disposable thermometers in my old-school fridge, but when we bought our Brisbane house we bought a new fridge which displays the fridge and freezer temps continuously (although I should check on how to validate).

The fridge also has an ice and water dispenser, which I used to have but lost in the divorce or move(s), it’s all a blur now.

A transdisciplinary observational study, coupled with a web-based survey, was conducted to investigate refrigerated storage of food, in five European countries.

The investigated consumer groups in this study were: young families with small children and/or pregnant women, elderly people, persons with an immunodeficient system, and young single men.

The refrigerator temperature was monitored for approximately two weeks using a temperature data logger. Variables such as country, income, age of refrigerators, education, living area, refrigerator loading practices had no significant effect (p > 0.05) on the overall average fridge temperature, whereas consumers’ practices showed a significant influence (p < 0.05) on registered temperature values.

Compared to temperatures inside the fridges belonging to young families and young single men group, the temperatures inside refrigerators belonging to elderly was in the temperature danger zone (5–63 °C). The lowest temperatures were recorded in UK consumers’ refrigerators, whereas the highest were in French households. Presence of Listeria monocytogenes was confirmed in three refrigerators out of 53 sampled (two in Romania and one in Portugal).

The most vulnerable category to food safety risks is represented by elderly persons with low education, unaware of safe refrigeration practices and the actual temperature their fridges are running.

Time-temperature profiles and listeria monocytogenes presence in refrigerators from households with vulnerable consumers

Food Control vol. 111 May 2020

LoredanaDumitrașcu^a, Anca IoanaNicolau^a, CorinaNeagu^a, PierrineDidier^b, IsabelleMaître^c, ChristopheNguyen-The^b, Silje ElisabethSkuland^d, TrondMøretrø^e, SolveigLangsrud^e, MonicaTruninger^f, PaulaTeixeira^g, VâniaFerreira^g, LydiaMartens^h, DanielaBorda^a

https://doi.org/10.1016/j.foodcont.2019.107078

https://www.sciencedirect.com/science/article/pii/S095671351930667X?via%3Dihub

Student dies after eating five-day old pasta that had been left out

Posted on January 28, 2019 by Douglas Powell

(Correction: This actually happened in 2008 and the paper was published in 2011. Still a good reminder of the importance of temperature control.)

Who doesn’t experiment in college?

But meddling with microbiology can be particularly risky.

A student died after eating leftover pasta that had been left on his kitchen benchtop for five days.

The 20-year-old from the Brussels in Belgium became sick after eating leftover spaghetti with tomato sauce which had been prepared five days earlier and stored at room temperature.

After becoming violently ill, he went to bed to try and sleep the sickness off, only to be found dead in bed the next morning by his devastated parents.

An autopsy later revealed he died from Bacillus cereus.

The story has been featured by Dr Bernard, a licenced practitioner who studies and shares bizarre medical cases from around the world on his YouTube channel.

Dr Bernard analysed the case, which originally featured in the US Journal of Clinical Microbiology, along with several others in a dramatised re-enactment, explaining the harmful bacteria caused AJ’s liver to shut down.

Samples of spoiled pasta and tomato sauce samples were also analysed, with the National Reference Laboratory for Food-borne Outbreak confirming the spaghetti was contaminated with “significant amounts” of the B. cereus — while it was absent in the sauce.

‘Better think about the consequence of (temperature abuse) actions’ Over 700 sick from C. perfringens at one Chipotle

Posted on August 16, 2018 by Douglas Powell

Chipotle’s head of food safety, Jim Marsden, has been conspicuously silent after at least 647 patrons at a single Chipotle restaurant in Powell (no relation), Ohio, were sickened with Clostridium perfringens.

As one of my colleagues said, Preventing C. perfringens is kind of like food safety 101. They must’ve had a massive temperature abuse situation.

In response, CEO Brian Niccol said Chipotle will start retraining all restaurant employees on food safety and wellness protocols next week.

Uh-huh.

#MeToo

Maybe not so slightly pink: Properly cooked pork chops may contain threat of Listeria and Salmonella for consumers

Posted on September 28, 2017 by Douglas Powell

If you are eating leftover pork chops that have not been cooked well-done, you’re putting yourself at risk for Salmonella and Listeria exposure. While many individuals prefer to consume their pork medium, a new study published in Risk Analysis: An International Journal revealed that cooking pork chops to an acceptable temperature does not completely eliminate pathogens, providing these cells with the opportunity to multiply during storage and harm consumers.

The study, “Impact of cooking procedures and storage practices at home on consumer exposure to Listeria monocytogenes and Salmonella due to the consumption of pork meat,” found that only pork loin chops cooked well-done in a static oven (the researchers also tested cooking on a gas stove top) completely eliminated the Listeria and Salmonella pathogens. Other levels of cooking, i.e. rare and medium, while satisfying the requirements of the product temperature being greater than or equal to 73.6 degrees Celsius and decreasing the pathogen levels, did leave behind a few surviving cells which were then given the opportunity to multiply during food storage before being consumed.

It is generally believed that when meat is heat treated to 70 degrees Celsius for two minutes, a one million cell reduction of E. coli, Salmonella, and Listeria is achieved and thus the meat is free of pathogens and safe to eat. However, a report by the European Food Safety Authority revealed that more than 57 percent of Salmonella outbreaks in 2014 were in the household/kitchen, and 13 percent were associated with inadequate heat treatment.

“The results of this study can be combined with dose response models and included in guidelines for consumers on practices to be followed to manage cooking of pork meat at home,” says Alessandra De Cesare, PhD, lead author and professor at the University of Bologna.

In order to assess the pathogen levels in cooked pork, the researchers, from the University of Bologna, the Institute of Food Engineering for Development and the Istituto Zooprofilattico delle Venezie, tested 160 packs of loin chop. The samples were experimentally contaminated with 10 million cells of L. monocytogenes and Salmonella to assess the reduction in pathogens after cooking, in accordance with the Food Safety and Inspection Service (FSIS) and British Retail Consortium (BRC) specifications (ensuring a reduction of at least 100,000 and 1,000,000 cells, respectively). The samples were contaminated on the surface, to mimic contamination via slaughter and cutting.

The samples were divided into groups to be cooked either on gas with a non-stick pan or in a static oven. In each setting, the pork chops were cooked to rare, medium, and well-done. For each cooking combination, 40 repetitions were performed for a total of 240 cooking tests.

The researchers also interviewed 40 individuals between the ages of 20 and 60 to determine household consumer habits regarding doneness preferences. Prior published research was referenced to define meat storage practices and the probability that consumers store their leftovers at room temperature, in the refrigerator or discard them immediately. Growth rate data for the pathogens at each temperature were obtained using the software tool ComBase.

The only cooking treatment able to completely inactivate the pathogens was oven well-done, which achieved a reduction between one and 10 million cells. Statistical analyses of the data showed significant differences related to level of cooking and cooking procedure. However, the researchers explained that factors such as moisture, water activity, fat levels, salts, carbohydrates, pH, and proteins can impact the cooking treatment and effectiveness and, as a consequence, on bacteria survival. These results emphasize the needs to consider the form of pork (such as whole muscle versus ground) being cooked, in addition to the final temperature necessary to inactivate pathogens.

The results show that a reduction between one and 10 million of pathogen cells was reached when applying all of the tested cooking treatments, with product temperatures always reaching 73.6 degrees Celsius or greater. However, according to the simulation results using the obtained cell growth rates, the few surviving cells can multiply during storage in both the refrigerator and at room temperature, reaching concentrations dangerous for both vulnerable and regular consumers.

After storing leftovers, there was a probability for the concentration of pathogens to reach 10 cells ranging between 0.031 and 0.059 for all combinations except oven well-done. Overall, the mean level of exposure to Listeria and Salmonella at the time of consumption was one cell for each gram of meat. The results obtained from this study can be implemented in guidelines for consumers on practices to follow in order to manage cooking pork meat at home.

19 sickened: Temperatures matter; C. perfringens outbreak at a catered lunch Connecticut, 2016

Posted on September 8, 2017 by Douglas Powell

The U.S. Centers for Disease Control reports in September 2016, the Connecticut Department of Public Health was notified of a cluster of gastrointestinal illnesses among persons who shared a catered lunch.

The Connecticut Department of Public Health worked with the local health department to investigate the outbreak and recommend control measures. Information about symptoms and foods eaten was gathered using an online survey. A case was defined as the onset of abdominal pain or diarrhea in a lunch attendee <24 hours after the lunch. Risk ratios (RRs), 95% confidence intervals (CIs), and Fisher’s exact p-values were calculated for all food and beverages consumed. Associations of food exposures with illness were considered statistically significant at p<0.05. Among approximately 50 attendees, 30 (60%) completed the survey; 19 (63%) respondents met the case definition. The majority of commonly reported symptoms included diarrhea (17 of 18), abdominal pain (15 of 16), and headache (7 of 15).

The median interval from lunch to illness onset was 5.3 hours (range = 0.4–15.5 hours) for any symptom and 7 hours (range = 2.5–13 hours) for diarrhea. Analysis of food exposures reported by 16 ill and 10 well respondents (four respondents did not provide food exposure information) found illness to be associated with the beef dish (RR = undefined; CI = 1.06–∞; p = 0.046) (Table). All 16 ill respondents reported eating the beef. Coffee was also associated with illness; however, all 13 coffee drinkers who became ill also ate the beef. Eating cake approached significance (p = 0.051); all 10 cake eaters who became ill also ate the beef.The caterer had begun preparing all dishes the day before the lunch. Meats were partially cooked and then marinated in the refrigerator overnight. In the morning, they were sautéed 2 hours before lunch. Inspection of the facility found the limited refrigerator space to be full of stacked containers that were completely filled with cooked food, disposable gloves that appeared to have been washed for reuse, and a porous wooden chopping block.

The caterer’s four food workers reported no recent illness. Stool specimens from the food workers and from four ill attendees all tested negative for norovirus, Campylobacter, Escherichia coli O157, Salmonella, and Shigella at the Connecticut State Public Health Laboratory. All eight specimens were sent to the Minnesota Department of Health Public Health Laboratory, where additional testing was available. Two specimens from food workers were positive for enterotoxigenic Escherichia coli by polymerase chain reaction, but no enterotoxigenic E. coli colonies were isolated. Seven specimens (four from food workers and three from attendees) were culture-positive for Clostridium perfringens, and specimens from all attendees contained C. perfringens enterotoxin. Pulsed-field gel electrophoresis of 29 C. perfringens isolates from the culture-positive specimens found no matches among attendee isolates, but demonstrated a single matching pattern between two food worker specimens. No leftover food items were available for testing.

C. perfringens, a gram-positive, rod-shaped bacterium, forms spores allowing survival at normal cooking temperatures and germination during slow cooling or storage at ambient temperature (1). Diarrhea and other gastrointestinal symptoms are caused by C. perfringens enterotoxin production in the intestines. Vomiting is rare and illness is usually self-limited, although type C strains can cause necrotizing enteritis (1).

Symptoms reported were consistent with C. perfringens infection, with a predominance of diarrhea, and median diarrhea onset time was at the lower end of the typical C. perfringens incubation period (6–24 hours) (1). C. perfringens enterotoxin detection in the stool of two or more ill persons confirms C. perfringens as the outbreak etiology (2). Both C. perfringens and enterotoxigenic E. coli can colonize asymptomatic persons (3,4), which might explain the presence of these pathogens in the stools of asymptomatic food workers. Pulsed-field gel electrophoresis did not identify the C. perfringens strain responsible for the outbreak, but findings add to the evidence for a wide variety of C. perfringens strains, not all producing C. perfringens enterotoxin (5).

C. perfringens outbreaks are typically associated with improper cooling or inadequate reheating of contaminated meats (1), which might have occurred with the beef dish. The restaurant was advised about the need for adequate refrigeration and best practices for cooling foods, including using stainless steel rather than plastic containers, avoiding filling containers to depths exceeding two inches, avoiding stacking containers, and ventilating hot food. Upon follow-up inspection, staff members discarded disposable gloves after one use, used only food-grade cutting boards, and maintained proper food temperatures for hot holding, cold holding, cooling, and reheating, as outlined in the Food and Drug Administration Food Code.

An estimated 1 million illnesses in the United States each year are attributable to C. perfringens, but fewer than 1,200 illnesses are reported annually with C. perfringens outbreaks (6). C. perfringens testing is not routine for foodborne outbreaks; even if testing is unavailable, C. perfringens should be considered when improper cooling, inadequate reheating, and improper temperature maintenance of meat are identified.

I don’t see color, it doesn’t matter: UK hamburger edition

Posted on August 26, 2016 by Douglas Powell

Don’t burger up your bank holiday.

Get it? Don’t bugger it up? Burger it up?

Those bureaucrats at UK’s Food Standards Agency are really yukking it up, focused on stupid jokes rather than evidence-based communications.

FSA has long been in its own undersirable class when talking about food safety risks, and class is so very important to the Brits.

FSA is great is talking at people rather than talking with people (a huge difference, like educating versus providing information).

FSA’s idea of risk communication is to commission a meaningless survey – people lie, especially about food and drink – which found that despite 71% of people stating that they are concerned about food poisoning, over a third (36%) of Brits would eat a burger that isn’t fully cooked through. More than one in 10 said that they actually prefer burgers cooked this way. When cooking them at home 81% of those admit to undercooking them. So we at the FSA are encouraging all those who are getting their barbecues out this weekend to ensure they cook their burgers all the way through – until steaming hot throughout, there’s no pink meat in the middle and the juices run clear.

Those scientifically meanginless terms – steaming hot, no pink – have featured prominently in FSA foodsafetytalk for years, with steaming hot replacing piping hot.

Lead FSA policy thingy said something that is not worth repeating because it ignores the risks associated with needle-tenderized steaks.

And we’ve been over this so many times before.

The BBC repeated the advice verbatium in its latest version of PR blowjobs rather than something resembling journalism.

Use a thermometer and stick it in.

And now this.

It ain’t happening at retail: Cut cantaloupe needs to be stored at 4C to control Listeria growth

Posted on August 23, 2016 by Douglas Powell

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.

http://online.liebertpub.com/doi/abs/10.1089/fpd.2016.2160

Safety of sun tea

Posted on July 13, 2016 by Douglas Powell

Nancy Haberstich, creator and founder of Nanobugs Inc. writes in the Lincoln Journal Star that the appeal of sun tea is the ease at which you can make it — pop a bunch of tea bags in a big jar of water and set it in the sun.

However, sun tea does come with its risks.

Microbes can easily contaminate tea leaves. When added to water, these microbes can be revived and start multiplying — especially if they sit in warmer temperatures of 40 to 140 degrees.

Tea made with the sun’s rays will not get hotter than 130 degrees, Haberstich said. The caffeine in black tea will help prevent some bugs from flourishing for a few hours, but its effects won’t last beyond that. Herbal teas are an even worse bet for brewing in sunlight because they lack caffeine.

For safer iced tea, boil water and pour it over tea bags or tea leaves. Steep to desired concentration, then add ice and serve. Iced tea makers are also safe alternative, if they heat water to 195 degrees.

A new trend is the “cold brew” method — which is safe as the tea or coffee is “brewed” overnight in a refrigerator (which is colder than 40 degrees).

RTE salad storage temps should be reduced in Sweden

Posted on June 18, 2016 by Douglas Powell

Prepacked ready-to-eat mixed ingredient salads (RTE salads) are readily available whole meals that include a variety of ingredients such as raw vegetables, cooked meat, and pasta.

As part of a trend toward healthy convenience foods, RTE salads have become an increasingly popular product among consumers. However, data on the incidence of foodborne pathogens in RTE salads are scarce.

In this study, the microbiological safety of 141 RTE salads containing chicken, ham, or smoked salmon was investigated. Salad samples were collected at retail and analyzed using standard methods for Listeria monocytogenes, Shiga toxin–producing Escherichia coli (STEC), pathogenic Yersinia enterocolitica, Salmonella, and Campylobacter spp.L. monocytogenes was isolated from two (1.4%) of the RTE salad samples.

Seven (5.0%) of the samples were positive for the ail gene (present in all human pathogenic Y. enterocolitica isolates) and three (2.1%) of the samples were positive for the Shiga toxin genes stx 1 and/or stx 2. However, no strains of pathogenic Y.enterocolitica or STEC were isolated.

Thus, pathogens were found or suspected in almost 1 of 10 RTE salads investigated, and pathogenic bacteria probably are present in various RTE salads from retail premises in Sweden.

Because RTE salads are intended to be consumed without heat treatment, control of the ingredients and production hygiene is essential to maintain consumer safety. The recommended maximum storage temperature for RTE salads varies among countries but can be up to 8°C (e.g., in Sweden). Even during a short shelf life (3 to 5 days), storage at 8°C can enable growth of psychrotrophs such as L. monocytogenes and Y. enterocolitica. The maximum storage temperature should therefore be reduced.

Foodborne bacterial pathogens in retail prepacked ready-to-eat mixed ingredient salads

Journal of Food Protection®, Number 6, June 2016, pp. 896-1055, pp. 978-985(8)

Söderqvist, Karin; Thisted Lambertz, Susanne; Vågsholm, Ivar; Boqvist, Sofia

http://www.ingentaconnect.com/contentone/iafp/jfp/2016/00000079/00000006/art00011

Burgers may need higher cooking temperature to be safe from E. coli

Posted on June 3, 2016 by Douglas Powell

Food safety friend Lynn McMullen at the University of Alberta, and others have found that cooking ground beef at 71C — the level of heat long advised by Health Canada — does not always eliminate all the strains of Escherichia coli.

“We’ve been hammering consumers for years to cook chicken properly, to handle it properly, and to do the same with ground beef but still we seem to have these outbreaks of E. coli (attributed to hamburgers),” said food microbiologist McMullen.

“Does this explain why? It might.”

McMullen, fellow food microbiologist Michael Gänzle, and several graduate students, first became aware of the inconsistent behaviour of E. coli eight years ago.

For decades, scientific papers about the thermal killing of microorganisms have noted that there were sometimes survivors. But little attention was paid to that information until 2008, when McMullen and Gänzle assigned a student to look for differences in thermal survival amongst organisms in a large collection of E. coli from beef, which the U of A happens to house.

The first student, Elena Dlusskaya, showed that one organism had survived for 70 minutes at 60C. Both professors felt her study must be flawed, because most E. coli are killed just a few seconds after such heat application. Repeating her experiments twice produced the same odd results.

Then Dlusskaya compared her cultures to those from other labs, which already had published survival values. Again, she found that some of the U of A’s cultures were behaving differently.

“These organisms aren’t supposed to survive, but every once in a while they do,” said McMullen. “So we decided to find out why. We looked at the genomes to see what was different.”

Working with postdoctoral fellow Ryan Mercer, they discovered a suite of 16 genes that are found only in the highly heat-resistant strains of E. coli under wet conditions (i.e. fresh meat). This genomic grouping is called the locus of heat resistance, or LHR.

Hunting through the genome databases for LHR, they saw that it exists in about two per cent of all E. coli in the databases and is present in both the harmless and pathogenic strains.

“If it’s in two per cent of all E. coli, and in pathogenic E.coli, there’s the potential that a pathogen could survive the standard cooking protocols for ground beef. It could mean we have to change the guidelines for cooking meat, because 71C may not be enough.”

Salt also makes E. coli bacteria heat resistant, though McMullen and the other researchers don’t know why.

Though McMullen and the other researchers haven’t discovered what temperature will ultimately kill all E. coli, McMullen recommended using a thermometer and cooking meat at 71 C to 73 C. “It doesn’t matter when you’re grilling any ground meat, you should be using a thermometer.”

Genetic determinants of heat resistance in Escherichia coli

Front Microbiol. 2015; 6: 932.

Published online 2015 Sep 9. doi: 10.3389/fmicb.2015.00932

Ryan G. Mercer, Jinshui Zheng, Rigoberto Garcia-Hernandez, Lifang Ruan, Michael G. Gänzle, and Lynn M. McMullen

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4563881/

Escherichia coli AW1.7 is a heat resistant food isolate and the occurrence of pathogenic strains with comparable heat resistance may pose a risk to food safety. To identify the genetic determinants of heat resistance, 29 strains of E. coli that differed in their of heat resistance were analyzed by comparative genomics. Strains were classified as highly heat resistant strains, exhibiting a D60-value of more than 6 min; moderately heat resistant strains, exhibiting a D60-value of more than 1 min; or as heat sensitive. A ~14 kb genomic island containing 16 predicted open reading frames encoding putative heat shock proteins and proteases was identified only in highly heat resistant strains. The genomic island was termed the locus of heat resistance (LHR). This putative operon is flanked by mobile elements and possesses >99% sequence identity to genomic islands contributing to heat resistance in Cronobacter sakazakii and Klebsiella pneumoniae. An additional 41 LHR sequences with >87% sequence identity were identified in 11 different species of β- and γ-proteobacteria. Cloning of the full length LHR conferred high heat resistance to the heat sensitive E. coli AW1.7ΔpHR1 and DH5α. The presence of the LHR correlates perfectly to heat resistance in several species of Enterobacteriaceae and occurs at a frequency of 2% of all E. coli genomes, including pathogenic strains. This study suggests the LHR has been laterally exchanged among the β- and γ-proteobacteria and is a reliable indicator of high heat resistance in E. coli.

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