When you buy vegetables at a farmers market, often you will get root vegetables (e.g. potatoes, carrots) that are unwashed and with its dirt still clinging on them. I heard somewhere that this will prolong its shelf life. Is this true? If so, how?
Not really, the dirt's there because of:
- Authenticity: dirty veggies make people think "garden-fresh"
- Laziness: farmers don't want to spend much time cleaning their vegetables
Washing to remove dirt won't shorten the shelf life, but mechanically removing dirt (as in with a hard brush) might in some cases as it could remove or puncture skins or peels.
From what I have understood, at least potato farmers prefer to store potatoes "dirty" ,mostly because the soil/clay will help protect the surface of the potato and keep it from dissipating moisture.
If you think about it, the natural way for wintering a potato (or a root vegetable) is for it to stay in the ground, in soil and wait for the next spring. So the best way to store a harvested potato , is to keep it in earth-like temperature and humidity.
Also to add one point I just realized. Soil will probably stabilize the moisture by capturing/releasing it to avoid formation of drops of moisture, which will probably stop fungi and mold from getting hold.
I leave the dirt on my veggies but not to prolong their life. I compost peelings, and when I peel without washing first, that dirt goes in the compost. When I wash first (perhaps weeks before I use them), the dirt goes in my septic tank, which doesn't help my garden.
Occasionally I will buy veggies from the supermarket and they are always pristine. They do not spoil faster than the from-my-farmer veggies with a little dirt on them. This could be because any that get scratched or bruised in the washing process are thrown away before reaching the store. But it shows there is no property of the clinging dirt that extends storage life. As long as you wash them carefully there should be no problem. But there's also no compelling reason to wash them earlier than you need to.
Definite don't wash. In pre- supermarket dats no veg's were washed and you could keep them all through the winter if stored correctly. Nowadays, they wont keep a week, plus a lot of there natural flavour has gone. I dread to think whats growing on them inside the plastic bag in the fridge, urghhh,!!Providing fresh unwashed veg are kept cool and frost free, in the dark you will have no problems at all.