What is the best way to clean fruits and vegetables?

All fruits and vegetables should be washed well with water. A scrub brush should also be used on for hard-skinned fruits (for example, apples and cantaloupe) and vegetables with irregular skins (such as squash and potatoes) Following these procedures will get them as clean as commercial washes. If you want to use something stronger than water alone, add 1 tablespoon of vinegar to 1 gallon of water for clean fruit and vegetable surfaces. Rinse them well under clean running water after treating with the vinegar solution. Soft-skinned fruits (berries, pears, etc.) can be rinsed or submerged in water. (If submerging, change the water once,) Allow the produce to drip to remove most of the water. Root vegetables especially (potatoes, carrots, beets, and turnips) should be scrubbed with a vegetable brush to remove any soil adhering to the skin. More tender vegetables (for example, lettuce, broccoli, and cauliflower) should be gently cleaned.

Fruits and vegetables should not be washed until right before they are used. Wet surfaces, even in the refrigerator, provide a good surface for mold growth. Mold will spoil the fruit or vegetable, and some kinds can make both fruits and vegetables unsafe to eat if they produce mycotoxins, (chemicals that can permeate the tissue of fruits and vegetables and are harmful to human health).
 
Fruits and vegetables should be washed even if they are going to be peeled because bacteria from the peel can contaminate the flesh during the peeling process. If they are to be peeled and then consumed raw, they should be rinsed, peeled, and then rinsed again.
 
Because fruits are very acidic, most bacteria that can cause illness won’t grow on them; however they can serve as “carriers” of disease-causing illness bacteria like E. coli.
 
Peeled vegetables (for instance, potatoes and beets) should be cooked right after they are peeled. If they are to be consumed raw, they should be loosely covered with plastic film and refrigerated. All vegetables should be cleaned immediately before consuming or cooking.
 
Source(s):
Susan Brewer, Ph.D, University of Illinois, Department of Food Science and Human Nutrition