Vinegar helps prevent spoilage by killing bacteria present on the berries, helping to make them last longer in your refrigerator. The vinegar wash is most effective with distilled white vinegar mixed at a ratio of 1 cup of vinegar for every 3 cups of water. Use enough vinegar and water to completely cover the berries when placed in a bowl. A single pint of blueberries, for example, can be placed in a small bowl and might only require 1/2 cup of vinegar and 1 1/2 cups of water to cover them, while several quarts of strawberries would need a large mixing bowl and as much as 1 quart of vinegar and 3 quarts of water.

The berries should be left in the diluted vinegar mixture for about 10 minutes to soak. After the soaking period, rub each berry well between your fingers to ensure all dirt and bacteria are washed away. Leave the berries whole while washing and cut them later, if desired.

Vinegar is often used to pickle fruits and vegetables, but the short soaking and washing period has no adverse effects on the berry taste. Each berry must be thoroughly rinsed after washing to remove all traces of the vinegar. After moving the berries from the vinegar solution to a colander, run cold water over the berries to rinse. Turn the berries frequently to ensure all sides are thoroughly rinsed. Leave the colander in the sink so excess water drains.

Vinegar wash is supposed to help berries last longer, but berries can spoil rapidly despite these efforts if they're stored in the refrigerator while wet. Before repackaging the berries and storing them in the refrigerator, line the counter with paper towels and kitchen towels. Spread the berries evenly over the towels and leave them to dry for an hour or two. If necessary, blot them with paper towels to remove additional surface moisture. If you don't want to devote the time and effort to thorough drying, you can wash small amounts of berries with vinegar as you need them. Unfortunately, when you don't wash them immediately, you don't reap the anti-spoilage benefits of the vinegar while the berries are stored in the refrigerator.