What is the point of washing produce in cold water?

Question

You can find tons of tips online saying you should always wash your produce. What is the point of it though? I mean with some hard produce, say carrots you can obviously give them a good scrub with a brush and I can see how thoroughly it cleans them. What about soft produce though?

I've just read a question regarding raspberries. The answer was to wash them gently in cold water. I can't imagine that this is actually cleaning them properly. Obviously if they're very dirty, then it'd remove the biggest dirt. Let's say though that there are some bacteria on it or parasite larvea. Obviously gentle dip in cold water won't help, will it?

Answer 1

For the most part, rinsing produce in cold water is for the purpose of removing pesticides and soil that may contain bacteria. You're not washing off bacterial colonies - whole peel-on vegetables and fruit have a protective coating (the peel) which prevents them from growing for the most part. However, dirt particles may contain bacteria - particularly if, for example, there was animal manure used to fertilize the crops (one reason why you need to wash organic produce just as much as conventional produce!)

See for example the NHS England guidelines for washing produce:

Washing will help remove bacteria, including E.coli, from the surface of fruit and vegetables.

Most of the bacteria will be in the soil attached to the produce. Washing to remove any soil is, therefore, particularly important.

Of course, produce that has more dirt in it (such as lettuce, which grows in dirt) will need more careful cleaning than tree fruit (which probably doesn't have too much on it beyond pesticides).

Answer 2

It's worth noting that from a food safety perspective, washing is not about eliminating all harmful bacteria and viruses, but reducing their amount to the extent possible (in addition to removal of pesticides, debris such as dirt, etc). Many pathogens cling to things like dirt better than fruit or vegetable skin, so even in the example of raspberries, rinsing can easily knock some dirt off.

To use handwashing as a proxy for washing vegetables, washing hands with water alone still results in a dramatic decrease in bacteria on your hands. In fact, much or most of the power of handwashing can be had with just running water and rubbing your hands together. Of course, if you have soap it should obviously be used.

Dosage is also important. In order to get sick from a pathogen, you have to come in contact with enough of it, often in the order of thousands or tens of thousands of it whether that be individual bacteria or viruses. So reduction is prevention, even if it's not perfect prevention.