Why Fruit and Vegetables Should Be Washed Before Eating, Not Before Storing
Health Canada advises storing mushrooms, tomatoes, lettuce and herbs unwashed and rinsing them just before use; strawberries keep 3 to 7 days at 0 °C. When to wash, with what, and what to do with melons and bagged salad.
Mushrooms are not washed until you are ready to use them, whole tomatoes are kept unwashed and uncovered at room temperature until ripe, and leafy greens and herbs are rinsed under running water immediately before eating. All three instructions come from Health Canada's guides for individual foods. The reason is the same in each case: water left on the surface after washing speeds up spoilage, while washing before eating removes what matters for safety. The FDA and the Croatian agency HAH phrase the rule the same way: produce is washed under running water before preparing or eating, and HAH adds "especially if eaten raw".
Moisture shortens shelf life: strawberries, lettuce, mushrooms
Strawberries keep 3 to 7 days at 0 °C (32 °F) and 90–95% relative humidity, lettuce 2 to 3 weeks at 0 °C, according to the University of Maine storage guide for fruits and vegetables. Those are cold-store conditions; for a home fridge Health Canada gives 3 to 7 days for leaf lettuce, 1 to 2 weeks for iceberg and 2 to 4 weeks for spinach. Strawberries are prone to grey mould (Botrytis cinerea), which Wikipedia lists as the main disease of the fruit; droplets of water on a washed berry give the mould exactly what it needs. Health Canada recommends keeping mushrooms in a paper bag in the fridge for up to 5 days, and never in a sealed container outside the fridge, because those conditions favour the bacterium that causes botulism.
| Produce | Wash before storing? | Where | Keeps (Health Canada / University of Maine) |
|---|---|---|---|
| Strawberries and berries | no | fridge, 0–4 °C (32–40 °F) | 3–7 days at 0 °C |
| Leaf lettuce | no | fridge | 3–7 days (iceberg 1–2 weeks) |
| Mushrooms | no | fridge, paper bag | up to 5 days |
| Fresh herbs | no | fridge, bag (basil at room temperature) | up to 5 days |
| Whole tomatoes | no | room temperature until ripe | ripe: fridge, a few days |
| Carrots | no | fridge | 2 weeks |
| Melon, watermelon | no; scrub before cutting | cut: fridge | cut: up to 4 days |
Before eating: running water, no soap
The FDA calls for washing under running water before preparing or eating, for all fruit and vegetables, including those whose skin is not eaten. Soap, detergent and commercial produce washes are explicitly not recommended by the FDA: fruit and vegetables absorb them despite rinsing and they can make you sick. Firm produce such as melons and cucumbers should be scrubbed with a clean produce brush, and after washing dried with a clean cloth or paper towel, which according to the FDA further reduces bacteria. Health Canada adds that greens and herbs should not be soaked in the sink, where they pick up bacteria from the sink itself.
Melons and everything that gets cut
Health Canada explains why even peeled produce is washed: bacteria from the rind of a melon transfer to the flesh when the knife cuts into it. So a whole melon is scrubbed thoroughly with a brush under running water before cutting. Cut melon keeps in the fridge for up to 4 days and is discarded if it has been at room temperature for more than 2 hours; the same applies to cut or peeled tomatoes, which keep 3 days in the fridge. Recipes with seasonal fruit and vegetables are in the recipes section.
Exceptions: bagged salad and basil
Pre-washed bagged salad labelled "washed" or "ready to eat" can, according to the FDA, be used without washing again; anyone who washes it anyway must make sure it does not touch unclean surfaces or utensils. Basil is the exception in the other direction: Health Canada recommends keeping it unwashed, uncovered and out of the fridge, because cold blackens its leaves. Other fresh herbs keep up to 5 days in a bag in the crisper drawer and are washed and patted dry with paper towels only before use or before freezing.
Apples and bananas away from the salad
Some fruit keeps ripening after harvest because it produces ethylene: apples, bananas, avocados, tomatoes, pears, peaches and kiwifruit are climacteric fruits, while strawberries, cherries, citrus, grapes, watermelon and peppers do not ripen further once picked (Wikipedia, Climacteric; FAO). Apples in cold storage at −1 to 4 °C (30–40 °F) keep 1 to 12 months, according to the University of Maine, and all that time they give off the gas that speeds up ripening in neighbouring produce. The practical consequence for the fridge: apples, pears and ripe tomatoes do not share a drawer with delicate lettuce and berries. More storage guides are on the blog.