The attack of the kitchen sponge

This brings me back to my Kitchen Crimes days when we analyzed dishcloths and sponges from 13 Winnipeg homes and confirmed the presence of pathogenic microorganisms. Given that bacteria are all around us and providing a medium that is moist, porous and contains food particles left at room temperature, the following is not surprising.

Peter Dockrill of Science Alert writes

Scientists in Germany have conducted what they say is the world’s first comprehensive study of contamination in used kitchen sponges, and it backs up we already feared: these soggy, porous ‘cleaning products’ are positively teeming with living bacteria.
Researchers led by Furtwangen University ran genetic sequencing on samples from 14 different used kitchen sponges and ended up finding 362 different types of bacteria happily lounging within all that comfortable, springy foam.
Fortunately for you and me, the majority of this bacteria was in fact not harmful – but some of it was.
“What surprised us was that five of the ten [types] which we most commonly found, belong to the so-called risk group 2 (RG2),” says lead researcher, microbiologist Markus Egert, “which means they are potential pathogens.”
These included Acinetobacter johnsonii, Moraxella osloensis, and Chryseobacterium hominis – which the researchers say can lead to infections – plus Acinetobacter pittii and Acinetobacter ursingii.
Of these, bacteria in the family Moraxellaceae was the most dominant kind found, backing up previous research on sponges.
Since Moraxellaceae is also common on human skin, the researchers speculate that it might be people touching sponges that introduces this particular contamination.
It’s also that we insist on then wiping these dense bug-ridden colonies over other, potentially clean surfaces in the house, including bench tops, appliances, and kitchen sinks.

What I would find more interesting is how much of what is on the sponge actually transfers over to a dish after the application of a detergent followed by a warm water rinse.

In addition to the sequencing, the team was able to visualise the presence of bacteria in the samples in 3D using a technique called fluorescence in situ hybridisation coupled with confocal laser scanning microscopy (FISH–CLSM).
The visualisations reveal how the large surface area, moist foam, and scattered food matter within the sponge provide the perfect, incubating habitat for bacteria.
So much so, in fact, that it’s almost hard to differentiate where the sponge (blue) stops and the bugs (red) start:
“Sometimes the bacteria achieved a concentration of more than five times 1010 cells per cubic centimetre,” says Egert.
“Those are concentrations which one would normally only find in faecal samples. And levels which should never be reached in a kitchen.”

The authors recommend changing the sponge on a weekly basis. Dischloths are no better.

TV kitchen crimes more about ratings than risk

Rob Mancini, the best–looking food inspector in Canada, writes:

The use of media in relaying food safety information can be a powerful tool. Food safety reality shows seem to be the fad these days as consumers are increasingly becoming aware of what actually occurs behind the scenes in restaurants. Truthfully, the more disgusting a restaurant is the better the ratings.

Rob_Mancini_001That’s reality I discovered when we shot Kitchen Crimes in Canada.

A well run, clean and sanitary restaurant will not draw in the ratings, but cockroaches and over-the-top chefs (Gordon Ramseys) will, so take what you see with a grain of salt. Either way, it gets people talking about food safety, which is a good thing. The BBC will be airing a new series of Food Inspectors that will focus on restaurant inspections, complaints, foodborne outbreaks, and providing food safety information to the public.

The wooden board wins

Food safety experts always recommend using two cutting boards, one strictly for meat and meat products and the other for fruits and vegetables to avoid cross contamination. Great advice, now what type of cutting board will reduce microbial counts after cleaning; plastic, wood, or marble?
Ninemsn reports:
Plastic comes a definite last and that’s because bacteria are able to breed in the cuts left by knives.
Marble came in second because bacteria spread everywhere. Marble also loses points because it’s tough on knives.
In the final wash-up, it was wood that blew the competition out of the water. This is no surprise to Professor Cliver. In many similar experiments, wood’s always been a winner.
Leila: "Why is wood so much better?"
Professor Cliver: "It’s a very porous material and the fluid is drawn into the wood by capillary action and if there are bacteria in the fluid they go in and they never come back alive."
Leila: "So the wooden boards kill the bacteria?"
Professor: "Well, they die off slowly. It may take a few hours, but all the same, they aren’t in a position to cause any trouble."
Leila: "So wood’s the way to go?"
Professor: "In my opinion."
But the professor adds a rider — be sure to choose a tight-grained hardwood board. If the wood’s too soft, those pesky bacteria can multiply in deep knife cuts.
I had the opportunity to swab a number of cutting boards when shooting the series Kitchen Crimes, both plastic and wooden boards. Microbial counts were consistently high because bacteria will hide in the cracks and crevices of the board rendering cleaning ineffective. It is important to toss or refinish your cutting board if it appears to be heavily grooved to prevent this from occurring.
Here are some tips on how to effectively clean and sanitize your board:
1. Wash with soap and water using friction.
2. Rinse with warm water.
3. Sanitize using a mild solution of bleach to water, approximately 5mL bleach to 500mL water.
4. Finally allow to air dry for optimum results.

ROB MANCINI: Top 10 Kitchen Crimes

During the production of Kitchen Crimes, a television series that dealt with food safety in the home as opposed to restaurants, there were a number of reoccurring themes that kept popping up.  So I developed my top 10 list of Kitchen Crimes to reflect my observations from the television show.

Tops was a severe lack of handwashing or inadequate handwashing. Handwashing typically involved a quick 2 second rinse with water and drying with a dirty tea towel. Family members would pet their dogs, cats, and even in one case a pet turtle, then go and prepare food without handwashing. So, number one on my list is:

1. Wash hands thoroughly before and after preparing food. Lather with soap and water for at least 15 seconds. Rinse well and dry with a clean towel.

A number of families were aware that their refrigerator should be kept at 4-5°C, but it was never checked.  Families were questioned on why they should maintain this temperature and the typical answer was that it would kill bacteria. The “danger zone” (4°C- 60°C) is conducive to rapid bacterial multiplication and at 4°C, bacterial multiplication is reduced, not stopped.

2. Invest in a fridge thermometer to ensure your fridge is at the right temperature. Cold foods should be kept below 4°C. Hot foods should be at a temperature greater than 60°C.

Throughout the filming of the series, families did not use thermometers to ensure food was properly cooked.  Visual inspection seemed to suffice.

3. Invest in a digital, tip-sensitive thermometer to ensure food is properly cooked.

It always bugs me when I see open packages of meat dripping bacterial laden juices on ready to eat foods, like vegetables or fruit.

4. In your refrigerator, meats should always be placed on the bottom shelves or in meat drawers in case of leakage and vegetables should be kept above to prevent cross contamination. All open or partially consumed foods should be packaged in airtight plastic storage containers.

In one episode, I dressed up in some sort of a space suit equipped with facial gear and so on (more for effect than anything else), but it was to prove a point. Mice like to eat food so if food is left on the floor, uncovered, mice will be there.

5. All dry goods need to be stored off the floor and sealed properly to prevent entry of rodents or insects.

To ensure food is adequately cooled in the fridge,

6. Do not over-pack the refrigerator or freezer. This restricts proper air flow and prevents the appliances from functioning efficiently.

This next one always gives me a headache, happens very frequently in restaurants. Vegetables and fruit typically do not undergo a subsequent cooking process which leads me to number

7 on my list: Prevent cross-contamination when preparing food by designating one cutting board for raw meats and another for vegetables or any ready-to-eat foods.

8. When cleaning surfaces, wash first with soap and water then sanitize with a mild solution of chlorine bleach and water.

If one is looking for the highest bacterial counts in the household, look no further.

9. Replace dishcloths and sponges on a daily basis.

10. After dishwashing, all utensils and dishware should be air dried to prevent cross-contamination from towels.