2. To preserve a food by adding a vinegar or brine mixture and then heat processing the foods in boiling water. Also referred to as "pickling" this process preserves food so it can be stored for long periods of time. All types of vegetables as well as numerous fruits are pickled so they can be perserved. To preserve foods, begin the pickling process within 24 hours after picking the item to be pickled. Select the foods when they are at the most tender stage of their development. A standard procedure for pickling may involve pre-cooking, blanching and raw packing in cans or jars. Some vegetables such as carrots, string beans, mushrooms, onions, and zucchini are raw packed. However asparagus is blanched prior to canning while beets are kept unskinned and pre-cooked for 30 minutes when pickling.