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What does your teatowel say about you?

  |   Science   |   11 Comments

Taking personality-test quizzes in glossy magazines to boost my self esteem is a thing of my past, but I am still a sucker for kitchen hygiene quizzes in reputable broadsheets.


As it seems are many of my peers. My tribe, a group of women belonging to an online parenting forum based in the UK (No, not Mumset), were getting very judgy with the answer to question number six in this quiz from the Guardian, UK. It stood between us and a perfect score. We have all brought up a reasonable number of children, run households and kitchens with no pressing need in to inform the local authorities of any home-grown communicable diseases so how could we all have got question six wrong?

Q: “How often should you change or wash your tea towels, sponges, aprons and cloths?” –

  1. when they get dirty
  2. at least once every two days
  3. when someone you want to impress comes over
  4. at least once a week

To a woman, we gave the answer as 2. .Guardian writer Mona Chalabi  claims the correct answer is 4. Oh, reader, how we judged her. Reactions ranged from the outraged to the anecdotal.

“We change our sponges and dishcloths frequently, running them through the dishwasher daily or soaking in bleach over night.”

“Once a week? Every day. Or after every time I cook.”

“If I knew you only changed your tea towels/dishcloths once a week I would never accept an invitation to dine at your house.”

One woman in rural Sussex proudly posted she hung her tea towels in front of her toasty-warm Aga between uses, but she did have a procession of goslings wandering through her kitchen on a regular basis and some of them were a bit clumsy.

“I was at a friend’s house once and her husband came in to the kitchen, blew his nose on the tea towel and hung it back up.”

gosling

Much fluffing and smoothing of feathers ensued and we all agreed that Mona Chalabi’s standards of hygiene left a lot to be desired while ours were beyond reproach. Until someone innocently asked. “What are you lot doing with your tea towels to  make them so dirty? I have a separate hand towel and wipe up big messes with kitchen paper so tea towels are only used for drying up.”

Fair Point.

Could all the indignation have been a reaction to guilty mixed-use tea towel abuse. Surely if a tea towel only saw the residual moisture from a thoroughly clean item then what was the problem?

margo-tea-towels

Nicely drying TTs policed by Rhodesian Ridgeback in Southwest London

 

 

Step in the food scientist, drawing on some years of experience in commercial kitchens and a spot of food-micro lab-prac on the Microbial Examination of Food Equipment, Surfaces and Air. The subject of the investigation: a domestic kitchen tea towel that is only used for drying clean pots and the a look at the kind of microbial load it could be expected to yield under the optimal conditions for microbial generation.

In the Food Industry Surface Testing is used to verify and establish:

  1. the effectiveness of cleaning and sanitation
  2. the frequency and effectiveness of cleaning and disinfection
  3. the presence of foodborne pathogens
  4. the source of environmental spoilage organisms
  5. the frequency of maintenance procedures and
  6. an evaluation of the hygienic design of equipment and premises (Standards Australia, 2001, p17)

If you want to know how we replicated the testing procedure in the laboratory practical scroll down to the very end of this post.

So how does that translate to domestic, family kitchens? Does my friend with the goslings have to shut down? If you run a tight ship and have a regular, good cleaning system in place you should pass the tea towel test (TT).

Let’s take it as a given that you are fairly houseproud then the highest level of risk of microbial contamination comes from those pieces of equipment that have direct contact with a food product, e.g. blades, storage tanks, pots and pans. Unless you are straining your homemade yogurt  through a tea towel, then you should be all right, in fact tea towels are classified as low risk zones.

So now we know the tea towel is not considered a food contact surface, and unlike utensils which should not have more than 100 colonies of yeast, moulds or bacteria per 100cm2  and it all depends on what types of organisms may be present. Here are the top three possibilities in a domestic kitchen, what they do to you and where they like to live.

Food poisoning and infection:

Staphylococcus aureus. You don’t need to ingest the viable bacteria itself to be poisoned by the enterotoxins it produces at a great rate. They can survive in quite dry conditions, down to a water activity level of 0.86 which is similar to cheese, and becomeespecially fruitful at around 42oC. Your screwed up partially damp tea towel that someone has recently handled without supervision and is keeping warm on the oven top could be host to Staph au., especially as it thrives in human nasal mucosal secretions and almost 50% of the population is thought to carry it.

Listeria moncytogenes –  a hardy bacteria able to reproduce rapidly at cool temperatures even faster at room temperature. Less than 10 colony forming units per gram at point of manufacture are considered extremely hazardous. It is very likely your kitchen drain is harbouring a colony and yet you and your family have probably developed a level of tolerance. If you were to open your kitchen for commercial uses this would be a big problem. It is unlikely it would survive for very long on a tea towel in any condition but not worth the risk.

E_-coli-6

E. Coli streaked for single colonies on a Blood Agar Plate

E. Coli –  from the faecal-oral route. No need to spell that one out. If anyone is using the tea towel to dry their hands and has generally shoddy personal hygiene standards then this bacteria is likely to be present. It’s virulence in kitchen conditions is one reason toilets may not open directly onto food preparation areas. Ingestion of this bacteria causes the classic symptoms associated with a touch of “Gastro”, and that’s not as in pub.

Yeasts and Moulds 

Occurring naturally in the air these spoilage flora are not necessarily going to poison or infect anyone. Therefore a little bit of green and black fuzz on your tea towel doesn’t mean you are a danger, but it doesn’t mean you’re keeping yourself nice, either. Again, air-dry those non-grubby tea towels and take the moisture factor out of the yeast and mould growing equation.

What did we do in commercial catering?

We air-dried all pots and utensils, hung our own personal tea towels from our apron strings and used them as oven gloves, wiped up the odd spill or messy hand and also to clean plate rims before surface, but to be fair a cook would usually have a separate one for reserved for this job.  Tea towels were always 100% natural fibre as synthetic polymers can melt on contact to heat and do not adsorb moisture well making uniform air drying a problem, and you know how those microbes like the damp. Also, in a good commercial kitchen the tea towels are supplied and laundered by commercial contractors and staff are encouraged to dip in to the seemingly endless clean supply during a shift. The best kitchens hang the used tea towels up to air on a drying rack before they are put in to the dirty laundry hampers and this is a to remove the vital Moisture component from the Microbes’ list of necessities, after all if the contract laundering company is late you could be growing  E. coli in your laundry hamper within 24 hours and that is not going to go down well with Environmental health.

teatowel-two

A fifteen pound sterling specimen drying nicely on a spotless hob in Bedforshire

 

 In general

Conclusion: If you are only using your tea towel to contact cleaned non-food surfaces, then leaving it to dry with as much surface area exposed as possible between uses it would seem that changing it only when you notice food residue or know it  has been subject to cross contamination is Perfectly Acceptable regardless of time-frame. In an ideal world you would wash them at above 60OC and separately, but if they are not ridden with filth in the first place and washed regularly it is unlikely microbes would be present in sufficient numbers to regenerate after normal washing. Be vigilant for instances of organic matter adhering to its surface as these can harbour micro organisms that may generate to critical levels. Also be vigilant for that woman’s dreadful husband. And do not cross contaminate with your own dirty hands. Even a tea towel splayed out in the hot sun to dry could harbour heat resistant infectious diseases such as Prions or Scrapie, so check yourself and your environs for those. Are those goslings having a good scratch on that aga as they waddle past?

If your tea towel has food scraps on it, because you wiped a washed pot that was not so well washed, or you used it to wipe your hands or that splash of milk from the kids’ breakfast or The Cat and you leave it scrunched up in the heat of the kitchen for 24 hours then the microbial load is likely to register in the Surface Test at possibly hazardous levels. Therefore, it is these factors which influence the scale of the bio-hazard and hygiene faux pas you are cultivating.

  • the source of microbial growth,  whether spoilage or pathogenic
  • how tight your kitchen-cleaning regime is to begin with
  • the conditions you give it for optimal growth such as Food, Moisture, Time and Temperature
  • or how resilient you and your family are to those microbes

 

A clean kitchen to begin with, using the tea towel to dry dishes and not hands or surfaces, hanging it out to dry and checking it for crusty bits and grime all influence how often you need to change it. Me, I  buy them by the dozen and always have a large fresh supply in my kitchen drawer. I have use one to wipe my hands with and one of a different colour to dry cleaned surfaces and dishes. I  try change them each time I finish cooking something or rather I select a fresh one each time I begin cooking, but I ‘m not perfect as I like to chuck the dirty ones in a corner of the back yard until I can get round to washing them. One of these days they will walk themselves to the washing machine if I don’t change my ways.

 

 

 

 

Official Microbial examination methods in Australia and NZ, if you are interested:

 

• Aseptically moisten a sterile swab in buffered peptone water (BPW).

 

• For utensils, rub the swab slowly and firmly three times over the surface most likely to be contaminated (between blades, in crevices, between tynes of a fork etc).

 

• For surfaces, moisten a swab as above and using the 10 x 10 cm2 template as a guide, rub the swab 10 times in a horizontal direction and 10 times in a vertical direction so that the entire area is swabbed.

 

• Return the swab to the BPW and rotate it to resuspend the microbes in the broth.

 

• Break off the head of the swab so it remains in the BPW. Make sure BPW bottle lid is on tight.

 

• Discard the handle of the swab.

 

• Vortex the BPW containing the swab to resuspend any microbes.

 

• Transfer 1 ml and 0.1 ml samples of BPW to labelled Petri dishes and pour in the molten Nutrient Agar (NA).

 

• Incubate plates at 30oC for 48 hours.

 

 

• Report the number of single colonies per utensil or surface in Table 1. An acceptable standard of hygiene is < 100 microbes per utensil or per 100cm2 of surface.

• Calculations need to take into account the number of colonies on the agar plate and the volume used in the testing technique.

 

 

11 Comments
  • Fiona | Jul 30, 2013 at 19:42

    Would the presence of a dog in the kitchen mean more regular tea towel changing?

    I am aghast someone would change their tea towel only once a week.

    • Crackling | Jul 30, 2013 at 21:11

      Not in your own family kitchen from which you were not going to commercially produce food for retail sale or service. And, you can see from the illustration, the dog does not have its bits on any food prep surfaces. Hope this helps

  • lucy molleson | Jul 31, 2013 at 01:20

    what happens if someone uses my teatowels for non – kitchen related DIY messes such as grout, silica sealant and expanding foam? Should I chuck him/them out?

    • Crackling | Jul 31, 2013 at 08:54

      I would advise withholding favours of all kinds for an indefinite period under those circumstances.

  • Roger | Jul 31, 2013 at 05:53

    That dog should not be near tea towels. Revolting

    • Crackling | Jul 31, 2013 at 08:53

      Don’t sit on the fence, Roger. If this were a commercial premises then, of course, a dog near any surface would be improper. However, there is a big difference between a family setting and a commercial premises for which the rules of Food Hygiene and Microbiology are written. The modern way of thinking around these issues is for the operator to show compliance and explain how standards are being upheld in their particular situation rather than to proscribe practices across the board.

      • Roger | Jul 31, 2013 at 20:06

        I disagree. Dogs lick their bottoms then lick tea towels

  • Karen | Jul 31, 2013 at 16:12

    Nice plating-out technique showing on that Petri dish.

    I iron my tea towels, does that help?

    • Crackling | Aug 1, 2013 at 08:25

      Yes, it does help (you feel useful).

  • joy | Jul 31, 2013 at 22:15

    The teatowels aren’t being used to dry the dog!

    I know that my teatowels get used for jobs other than drying the dishes, like mopping up spills etc. Therefore..they get changed very frequently. Once a week is horrible!

    I go for cheap and plentiful.

    • Crackling | Aug 1, 2013 at 08:26

      Yes, cheap and plentiful is best, but no synthetic fibres please.

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