Raspberries aren't as firm as other berries, and they fall apart easily during rinsing. Their quality also deteriorates rapidly after washing. To enjoy them at their best, wash them right before you are ready to eat them or include them in a recipe. Use a gentle touch, work in small batches and handle them as little as possible. Reserve any soft berries that didn't hold their shape during washing for making sauce or jam.
Line a cookie sheet or other flat baking pan, serving tray or wide platter with two thicknesses of paper towels.
Examine the raspberries and discard any that are crushed or show signs of decay, insect damage or disease. Remove and discard any bits of debris, such as twigs or leaves.
Transfer only enough raspberries to a colander or strainer to form a single layer in the cookie sheet.
Hold the colander under slowly running water and move it around to wet all the berries. Shake the colander gently to help the water drain from the hollow hulled-out sections of the berries. Use the spray attachment on your sink if you have one, and wet all of the berries lightly.
Transfer the berries to the cookie sheet or tray and gently pour them out onto the paper towels. Separate them to let them air dry.
Rinse the remaining berries and use second paper-towel-lined tray or cookie sheet if necessary.
Refrigerate the entire tray of berries until you are ready to use them in a dessert or other recipe. Transfer any berries intended for sauce or jam to a bowl and refrigerate it covered until you are ready to proceed.
Freeze the berries for long-term storage by placing the entire tray in the freezer for several hours, or until they are solid. Transfer the frozen berries to freezer bags or containers, and label them with the processing date.
Freeze raspberries for as long as eight months. Keep in mind that thawed raspberries will not be as firm as fresh ones. They will turn mushy as they thaw, but are still perfectly good for making desserts and sauces, for jam or jelly, and in smoothies.
The Food52 website suggests briefly soaking fresh raspberries in a solution of 1 part vinegar to 3 parts water. This works best with large very firm berries, as smaller berries tend to fall apart in the water. Dry the berries on paper towels, or spin them dry in a salad spinner lined with paper towels. The vinegar method destroys bacteria and mold, and can prolong the freshness of the berries for several days.